Synthesis and characterization of p-n junction ternary mixed oxides for photocatalytic coprocessing of CO2 and H2O

In the present paper, we report the synthesis and characterization of both binary (Cu2 O, Fe2 O3, and In2 O3 ) and ternary (Cu2 O-Fe2 O3 and Cu2 O-In2 O3 ) transition metal mixed-oxides that may find application as photocatalysts for solar driven CO2 conversion into energy rich species. Two different preparation techniques (High Energy Milling (HEM) and Co-Precipitation (CP)) are compared and materials properties are studied by means of a variety of characterization and analytical techniques UV-Visible Diffuse Reflectance Spectroscopy (UV-VIS DRS), X-ray Photoelectron Spectroscopy (XPS), X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and Energy Dispersive X-Ray spectrometry (EDX). Appropriate data elaboration methods are used to extract materials bandgap for Cu2 O@Fe2 O3 and Cu2 O@In2 O3 prepared by HEM and CP, and foresee whether the newly prepared semiconductor mixed oxides pairs are useful for application in CO2-H2 O coprocessing. The experimental results show that the synthetic technique influences the photoactivity of the materials that can correctly be foreseen on the basis of bandgap experimentally derived. Of the mixed oxides prepared and described in this work, only Cu2 O@In2 O3 shows positive results in CO2-H2 O photo-co-processing. Preliminary results show that the composition and synthetic methodologies of mixed-oxides, the reactor geometry, the way of dispersing the photocatalyst sample, play a key role in the light driven reaction of CO2 –H2 O. This work is a rare case of full characterization of photo-materials, using UV-Visible DRS, XPS, XRD, TEM, EDX for the surface and bulk analytical characterization. Surface composition may not be the same of the bulk composition and plays a key role in photocatalysts behavior. We show that a full material knowledge is necessary for the correct forecast of their photocatalytic behavior, inferred from experimentally determined bandgaps

Cinnamyl alcohol dehydrogenases in the mesocarp of ripening fruit of Prunus persica genotypes with different flesh characteristics: changes in activity and protein and transcript levels

Development of fruit flesh texture quality traits may involve the metabolism of phenolic compounds. This study presents molecular and biochemical results on the possible role played by cinnamyl alcohol dehydrogenase (CAD; EC 1.1.1.195) during ripening [S3, S4 I (pre-climacteric) and S4 III (climacteric) stages] of peach [Prunus persica (L.) Batsch] fruit with different flesh firmness [non-melting flesh (NMF) \u2018Oro A\u2019/melting flesh (MF) \u2018Springcrest\u2019 and \u2018Sanguinella\u2019] and color (blood-flesh Sanguinella). A total of 24 putative full-length PRUPE_CAD genes were identified (in silico analysis) in the peach genome. The most abundant CAD isoforms, encoded by genes located on scaffolds 8 and 6, were probed by specifically developed anti-PRUPE_CAD sc8 and by anti-FaCAD (PRUPE_CAD sc6) polyclonal antibodies, respectively. PRUPE_CAD sc8 proteins (SDS-PAGE and native-PAGE/western blot) appeared responsible for the CAD activity (in vitro/in-gel assays) that increased with ripening (parallel to PRUPE_ACO1 transcripts accumulation and ethylene evolution) only in the mesocarp of Oro A and blood-flesh Sanguinella. Accumulation of PRUPE_CAD sc8 transcripts (semi-quantitative RT-PCR) occurred in all three cultivars, but in Oro A and Springcrest it was not always accompanied by that of the related proteins, suggesting possible post-transcriptional regulation. Flesh firmness, as well as levels of lignin, total phenolics and, where present (Sanguinella), anthocyanins, declined with ripening, suggesting that, at least in the studied peach cultivars, CAD activity is related to neither lignification nor differences in flesh firmness (NMF/MF). Further studies are necessary to clarify whether the high levels of CAD activity/expression in Sanguinella play a role in determining the characteristics of this blood-flesh fruit

Rice Responses to Water Limiting Conditions: Improving Stress Management by Exploiting Genetics and Physiological Processes

Water-limiting conditions can severely affect rice yield. Therefore, increasing plant tolerance to water stress is a priority for many rice breeding programs. However, improving rice tolerance to this abiotic stress comes with several complications related to the seeding practices, the adopted water management system and the growth stage where water stress occurs. For this reason, it is challenging to outline single ideotypes showing traits suitable for overcoming drought at different times during the life cycle of rice in diverse cropping ecosystems. The current knowledge of genomics and biochemicals can contribute to drawing rice ideotypes flexible towards diverse water availability conditions. Traits identified in accessions of the wild ancestor of cultivated rice, as well as other wild rice species, in Oryza glaberrima and weedy rice were demonstrated to confer enhanced tolerance to water stress, while screenings of cultivated rice germplasms identified several genes/loci improving water stress resistance. New frontiers are represented by the dissection of the epigenetic control of stress tolerance and the implementation of the contribution of favorable microbiota. Innovative breeding technologies, whose feasibility is related to advancements in genomic analyses, are contributing to enhancing the knowledge-based development of water stress-tolerant rice varieties

Selective Aerobic Oxidation of 5-Hydroxymethylfurfural to 2,5-Diformylfuran or 2-Formyl-5-furancarboxylic Acid in Water by using MgO⋅CeO2 Mixed Oxides as Catalysts

Mixed oxides based on MgO⋅CeO2 were used as efficient catalysts in the aerobic oxidation of 5-hydroxymethylfurfural (5-HMF) to afford, with very high selectivity, either 2,5-diformylfuran (DFF, 99 %) or 2-formyl-5-furancarboxylic acid (FFCA, 90 %), depending on the reaction conditions. 5-Hydroxymethyl-2-furancarboxylic acid (HMFCA, 57–90 %) was formed only at low concentration of 5-HMF (<0.03 m) or in presence of external bases. The conversion of 5-HMF ranged from a few percent to 99 %, according to the reaction conditions. The oxidation was performed in water, with O2 as oxidant, without any additives. The surface characterization of the catalysts gave important information about their acid–base properties, which drive the selectivity of the reaction towards DFF. FFCA was formed from DFF at longer reaction times. Catalysts were studied by XPS and XRD before and after catalytic runs to identify the reason why they undergo reversible deactivation. XRD showed that MgO is hydrated to Mg(OH)2, which, even if not leached out, changes the basic properties of the catalyst that becomes less active after some time. Calcination of the recovered catalyst allows recovery of its initial activity. The catalyst is thus recoverable (>99 %) and reusable. The use of mixed oxides allows tuning of the basicity of the catalysts, avoiding the need for external bases for efficient and selective conversion of 5-HMF and waste formation, resulting in an environmentally friendly, sustainable process

Opto‐Electronic Characterization of Photocatalysts Based on p,n‐Junction Ternary and Quaternary Mixed Oxides Semiconductors (Cu2O‐In2O3 and Cu2O‐In2O3‐TiO2)

Semiconductor materials are the basis of electronic devices employed in the communication and media industry. In the present work, we report the synthesis and characterization of mixed metal oxides (MOs) as p,n‐junction photocatalysts, and demonstrate the correlation between the preparation technique and the properties of the materials. Solid‐state UV-visible diffuse reflectance spectroscopy (UV‐VIS DRS) allowed for the determination of the light absorption properties and the optical energy gap. X‐ray photoelectron spectroscopy (XPS) allowed for the determination of the surface speciation and composition and for the determination of the valence band edge. The opto‐electronic behavior was evaluated measuring the photocurrent generated after absorption of chopped visible light in a 3‐electrode cell. Scanning electron microscopy (SEM) measurements allowed for auxiliary characterization of size and morphology, showing the formation of composites for the ternary Cu2O‐In2O3 p,n‐mixed oxide, and even more for the quaternary Cu2O‐In2O3‐TiO2 MO. Light absorption spectra and photocurrent‐time curves mainly depend upon the composition of MOs, while the optical energy gap and defective absorption tail are closely related to the preparation methodology, time and thermal treatment. Qualitative electronic band structures of semiconductors are also presented

Transmembrane transporters and salt tolerance in temperate japonica rice

Several investigations aimed at identifying molecular tools useful for the selection and/or the constitution of high-yield salt tolerant rice have been successfully carried out, concerning in particular indica and/ or tropical rice genotypes. Te global warming process is nowadays determining the intrusion of saline wedge into coastal fresh-water streams, and the soil salt concentration of many European rice areas, where temperate rice cultivars are mainly grown, is more and more increasing. In order to identify molecular markers and/or new loci related to salt tolerance, a Genome Wide Association Study (GWAS) has been carried out using a panel of 277 japonica rice accessions. Te panel has been subjected to Genotyping By Sequencing and phenotyping concerning tolerance to a mild-salt stress soil condition (5 dS m-1) expressed at the 4th-5th leaf developmental stage using the Standard Evaluation Score (SES) proposed by IRRI. On the basis of GWAS, a QTL including a few genes that in the indica rice genome are localized within the major salinity tolerance-related QTL \u2018SalTol\u2019 have been identified. Among them, the Os01g0337500 gene encoding the vacuolar H+-pyrophosphatase 6 (OsOVP6) is present. Since the role of the OsOVP6 activity is considered central in regulating the cellular Na+ homeostasis in both roots and leaves, investigations comparing some elements of the complex mechanisms involved in this process have been carried out. A physiological approach evaluating this possibility has been conducted in two japonica rice varieties (Galileo and Virgo) that resulted salt-tolerant, in one japonica rice variety (PL12) known to be quite salt-susceptible, and in the salt-tolerant indica inbred genotype FL478 (containing the \u2018SalTol\u2019 QTL) as reference genotype. Te root and shoot Na+/K+ ratio, Na+ influx and K+ efflux, H+ extrusion activity, cytosolic and vacuolar pH by in vivo 31P-NMR techniques were evaluated in roots of the four rice genotypes. Te results obtained, together with the electrophysiological evaluation of the whole root Na+ conductance, allow to define a picture that may explain the different salt tolerance observed among the rice genotypes analyzed. As a whole, these results confirm the interest towards a deep allele mining analysis, concerning OsOVP6, within the most significant members of the japonica rice accession panel under investigation

The Trehalose-6-phosphate/SnRK1 system in the response to saline conditions during germination of two rice (O. sativa L., ssp. japonica) cultivars with different salt sensitivity

Soil salinity is extremely harmful for crops, and, among cereals, for rice (Oryza sativa L.), with particular regard to the ssp. japonica. Seed germination and seedling emergence are among the phenological stages particularly sensitive to this stress condition. A Genome Wide Association Study (GWAS) with a total of 31.421 SNPs was conducted on a collection of 277 japonica rice accessions phenotyped under mid-salinity considering germination kinetic parameters and seedling emergence rate. A few Marker-Trait Associations were identified on the basis of significant genotype-phenotype association analysis. Among the genes putatively involved in the salt response, two were particularly interesting: OsTPP7 (chromosome 9) and OsTPP10 (chromosome 7), both belonging to the family encoding Trehalose-6-Phosphate Phosphatase (TPP) catalyzing the dephosphorylation of Trehalose-6-Phosphate (T6P) to Trehalose. Salt stress affects carbohydrate production and the mobilization/use of C storage compounds altering the sink-source relationships, sugar allocation and energy metabolism. In this framework, the ratios T6P/Tre, regulated by TPP activity, acts as a signal in the cascade of events that regulate, through sugar metabolism, plant development with particular regard to seed germination and seedling growth. In turn, T6P regulates the activity of Snf1-Related protein Kinase-1 (SnRK1), a metabolic sensor able to regulate \u3b1-amylase and fundamental in maintaining C homeostasis under stress. Aim of the work was to establish the role of the SnRK1/Tre6P/Tre/Sucrose system and in particular of the OsTPP7 and OsTPP10 genes in the tolerance of japonica rice to salt stress during seed germination and early seedling development. In two model rice accessions (Olcenengo, tolerant, and SR113, sensitive) with opposite behavior in salt stress, biochemical and molecular analyses were conducted. In particular, have been considered: in the growing embryos, T6P, Tre, and sucrose levels, and OsTPP7-OsTPP10 gene expression; in the endosperm, the time-course of \u3b1-amylase activity. Te results define a picture coherent with the different effects of salt stress in Olcenengo and SR113. Functional characterization of the OsTPP10 gene and its allele mining analysis within the 277 rice accessions are in progress

Reference Genes for Real-Time PCR Quantification of MicroRNAs and Messenger RNAs in Rat Models of Hepatotoxicity

Hepatotoxicity is associated with major changes in liver gene expression induced by xenobiotic exposure. Understanding the underlying mechanisms is critical for its clinical diagnosis and treatment. MicroRNAs are key regulators of gene expression that control mRNA stability and translation, during normal development and pathology. The canonical technique to measure gene transcript levels is Real-Time qPCR, which has been successfully modified to determine the levels of microRNAs as well. However, in order to obtain accurate data in a multi-step method like RT-qPCR, the normalization with endogenous, stably expressed reference genes is mandatory. Since the expression stability of candidate reference genes varies greatly depending on experimental factors, the aim of our study was to identify a combination of genes for optimal normalization of microRNA and mRNA qPCR expression data in experimental models of acute hepatotoxicity. Rats were treated with four traditional hepatotoxins: acetaminophen, carbon tetrachloride, D-galactosamine and thioacetamide, and the liver expression levels of two groups of candidate reference genes, one for microRNA and the other for mRNA normalization, were determined by RT-qPCR in compliance with the MIQE guidelines. In the present study, we report that traditional reference genes such as U6 spliceosomal RNA, Beta Actin and Glyceraldehyde-3P-dehydrogenase altered their expression in response to classic hepatotoxins and therefore cannot be used as reference genes in hepatotoxicity studies. Stability rankings of candidate reference genes, considering only those that did not alter their expression, were determined using geNorm, NormFinder and BestKeeper software packages. The potential candidates whose measurements were stable were further tested in different combinations to find the optimal set of reference genes that accurately determine mRNA and miRNA levels. Finally, the combination of MicroRNA-16/5S Ribosomal RNA and Beta 2 Microglobulin/18S Ribosomal RNA were validated as optimal reference genes for microRNA and mRNA quantification, respectively, in rat models of acute hepatotoxicity

Analysis of cadmium root retention for two contrasting rice accessions suggests an important role for oshma2

Two rice accessions, Capataz and Beirao, contrasting for cadmium (Cd) tolerance and root retention, were exposed to a broad range of Cd concentrations (0.01, 0.1, and 1 M) and analyzed for their potential capacity to chelate, compartmentalize, and translocate Cd to gain information about the relative contribution of these processes in determining the different pathways of Cd distribution along the plants. In Capataz, Cd root retention increased with the external Cd concentration, while in Beirao it resulted independent of Cd availability and significantly higher than in Capataz at the lowest Cd concentrations analyzed. Analysis of thiol accumulation in the roots revealed that the different amounts of these compounds in Capataz and Beirao, as well as the expression levels of genes involved in phytochelatin biosynthesis and direct Cd sequestration into the vacuoles of the root cells, were not related to the capacity of the accessions to trap the metal into the roots. Interestingly, the relative transcript abundance of OsHMA2, a gene controlling root-to-shoot Cd/Zn translocation, was not influenced by Cd exposure in Capataz and progressively increased in Beirao with the external Cd concentration, suggesting that activity of the OsHMA2 transporter may differentially limit root-to-shoot Cd/Zn translocation in Capataz and Beirao

Carbon-dots conductometric sensor for high performance gas sensing

In this paper the first example of using C-dots (CDs) as sensing nanomaterial for monitoring low concentrations of NO2 in ambient air is reported. In the logic to support a green circular economy, CDs were prepared from a natural low cost precursor consisting in olive solid waste (OSW) by a simple pyrolysis process combined with chemical oxidation. Characterization data showed the formation of spherical CDs with dimensions in the narrow size range from 0.5 to 5 nm and charged with functional groups (COO- (carboxylate), C-O-C (epoxide) and C-OH (hydroxyl) imprinting excellent water colloidal dispersion. The nanomaterial was used to fabricate and test a conductometric gas sensor (CDs-sensor) that was found to exhibit excellent performances in terms of high and selective response to sub-ppm concentration of NO2 at low temperature (150 °C), low limit of detection (LOD) of 50 ppb, good reproducibility and stability over use and aging. To the best of our knowledge, this is the first example reported in the literature of CDs high performances gas sensing material. Results here presented pave the way for a new class of a carbon nanomaterial for gas sensing to be applied in the field of environmental monitoring