1,721,097 research outputs found
Challenges in developing reliable phosphorus predictive models: Unpredictable release under soil redox changes
Full text linkPhosphorus (P), crucial for plant nutrition, is unevenly distributed in the Earth's crust, necessitating its supplementation in agriculture through fertilizers. However, excessive use can lead to water pollution. Our research focuses on the P adsorbing complex, investigating P release due to flooding, using 12 well-characterized soils with contrasting properties. Our research measures directly the P-adsorbing complex using adsorption/desorption isotherms. We observed that the P concentration in the solution —sufficient to prevent desorption yet low enough to avoid further sorption by the soil— decreases when the soil undergoes complete reduction (anoxia). When grouped by similarity, calcareous soils exhibit higher maximum P adsorption capacities (Xmax) under alternating reducing conditions (ARC) compared to continuous reducing conditions (CRC). In slightly acidic soils, CRC leads to a wider spread in Xmax values than ARC. For acidic, organic matter-rich soils, ARC results in the highest Xmax values (123 mmol P kg−1 soil) compared to CRC, whereas in acidic, light-textured soils, CRC shows significantly higher mean Xmax values than ARC. Nevertheless, we were unable to develop a predictive model for soil P desorption based on key intrinsic properties and climate. When an environmental or anthropogenic transformation induces anoxia, the P released does not follow a predictable pattern
Zr/Hf ratio and REE behaviour: A coupled indication of lithogenic input in marginal basins and deep-sea brines
No full textThe distribution of dissolved Zr, Hf and Rare Earth Elements (yttrium and lanthanides, hereafter referred to as REE) in the Eastern Mediterranean seawater column was measured in the Kryos basin to evaluate the lithogenic contribution from both Nile River and Sahara and Arabian desert dust. We found dissolved Zr/Hf ratios below the signature of crustal rocks and chondrites; a phenomenon likely driven by the dissolution of the Mn-rich coating of atmospheric dust particles delivered from the desert. In deeper waters, Zr/Hf ratios are clustered close to the signature of crustal rocks and chondrites according to the different Zr and Hf dissolved speciation. The Zr/Hf ratio observed in the deeper 3300 m seawater column corresponds to the value found in the Atlantic Ocean. The REE distribution displays a negative Ce anomaly and a positive La anomaly throughout the shallow waters above a 75 m depth. Zr, Hf, and REE concentrations measured in the anoxic deep-sea brines from Tyro, Medee, and Thetis basins indicate that the dissolution of evaporite within Messinian levels is responsible for the high salt content of these brines and influence Zr/Hf fractionation in the aqueous phase. Hafnium shows stronger affinity relative to Zr for surfaces of salts and Mn–Fe oxyhydroxides. Zr/Hf values and the observed shale-normalised REE features suggest that Zr, Hf and REE are leached from Mn and Fe-rich coatings of desert particles in shallow water layers. This process can be responsible for the observed distribution of studied elements in the studied Eastern Mediterranean oxic seawater. In deep-sea brines, Zr, Hf and REE are released from Messinian evaporites
Elimination of bacterial contaminants in in vitro shoot cultures of 'MRS 2/5' plum hybrid by the use of Melia azedarach L. extracts.
No full textAbstract The antimicrobial activity of leaf and callus extracts of Melia azedarach was tested on in vitro shoot cultures of the peach rootstoch ‘MRS 2/5’ (Prunus cerasifera × Prunus spinosa) that were
heavily contaminated with Sphingomonas paucimobilis (Sp) and Bacillus circulans (Bc). The extracts were filter-sterilised and added at 0%, 1%, 5%, 10% and 20% to a modified Murashige and Skoog proliferation medium previously autoclave-sterilised. Up to about
17% shoots died with 10–20% extract, except for Sp contaminated
shoots, whose survival was reduced to 50% after treatment with 20% extract. No shoots died with 1% to 5% supplement. The undiluted leaf extrashowed bactericidal activity on plated Sp and Bc
isolates. The homogenates of shoots randomly collected from treated cultures were processed for bacterial colony counting. Thus the 10% supplement was the best treatment for ridding Bc-contaminated cultures of bacteria (although 5% had a similar
bactericidal effect), and allowing shoot growth and proliferation comparable to controls at the fifth subculture on a standard medium, while 20% extract was needed to eliminate Sp, and could induce higher growth and proliferation rates in surviving shoots
than in untreated cultures. Callus extract was ineffective. The bactericidal activity of the leaf extract seemed attributable to a synergistic effect of azadirachtin with other unidentified compounds
present in the extrac
ATR-FTIR chemical screening for adulterants and sugar characterisation in honeys
Full text linkThe search for improvements in honey analysis is an important topic due to the relevance that adulterations and variations of sugar composition have in this food.
Attenuated Total Reflectance Fourier Transform InfraRed spectroscopy (ATR-FTIR) is a reliable and fast analytical instrumentation for analysis of liquids, semi-solids and solids, which is currently used in food chemistry for qualitative and quantitative investigations.
This work is aimed to build a fast analytical method, using ATR-FTIR and Partial Least Square (PLS) chemometric tool, to quantitative determination of glucose, fructose and sucrose present in honeys.
We analyzed 25 honeys from Trentino and Sicily and a significant spectral range from the whole ATR-FTIR spectra were selected. Then a PLS multivariate calibration model was built by using mixtures of glucose, fructose and sucrose at various concentration. Samples for cross-validation were selected, thereby allowing quantitative evaluation of glucose, fructose and sucrose in all samples. Furthermore, a representative number of honeys were mixed with common adulterant syrups to simulate adulteration procedures and to verify the reliability of the ATR-FTIR technique in recognizing them.
Preliminary results revealed not only the quantitative reliability of ATR-FTIR spectroscopy in the evaluation of sugars in honeys, but also its ability in recognizing honey adulteration
Characterization of Leaf Essential Oil Composition of Homozygous and Heterozygous Citrus clementina Hort. Extan. and its Ancestors
Full text linkClementine is a natural tangor, resulting from an interspecific cross between mandarin and
sweet orange. Gametic embryogenesis, allowing the single-step development of complete homozygous line
from the heterozygous parents, increases the efficiency of perennial crop breeding programs. Tri-haploids
have been regenerated through pollen embryogenesis (specifically, by anther culture) of Citrus clementina
Hort. ex Tan., cv. Nules. Two of them (HOMO1 and HOMO2) have been acclimatized and grafted in vivo in
2000. Research regarding the chemical characteristics of plant regenerated by pollen embryogenesis or
gynogenesis are useful to study the “gametoclonal variation”, as well as for further application of haploidy
technology in Citrus breeding. For these reasons and with the aim to characterize these homozygous clementine
genotypes, in this study leaf essential oils were extracted by Clevenger apparatus and their chemical composition
was investigated by capillary GC-MS, comparing them with oils obtained from the heterozygous plant and
from its ancestors (clementine is a hybrid between sweet orange and mandarin). The obtained oil compositions,
submitted to a statistical analysis, are partitioned into groups using principal components analysis (PCA) and,
compared to those of both parents, distinguished in three major chemotypes sabinene/linalool, γ-terpinene and
methyl N-methylanthranilate
Two-dimensional polytypism of "crystalline" (C5Me5)ReO3
No full textCrystals of Cp*ReO3 present a rare case of two-dimensional polytypism. They consist of a polytypic packing (in the bc plane) of ordered polar chains of three-legged piano-stool Cp*ReO3 molecules (stacked head-to-tail along the a axis). The two-dimensional polytypism arises from the possibility of building a similar motif both with 2-fold screw axes and inversion centers as packing operators, i.e. from the possibility of packing together neighboring chains of equal or different polarity
Bioadhesive properties of a polyaminoacidic hydrogel. Evaluation by ATR-FTIR spectroscopy
No full textBIOADHESIVE PROPERTIES OF A POLYAMINOACIDIC HYDROGEL: EVALUATION BY ATR FT-IR SPECTROSCOPY
No full textThe bioadhesive properties of a novel chemical
hydrogel based on a polymer of protein-like structure, have
been investigated by using ATR FT-IR spectroscopy. In
particular, the copolymer PHG obtained by partial derivatization
of PHEA with GMA was chemically crosslinked by
UVirradiation at 313 nm. Crosslinked PHG was treated with
water to obtain a swelled sample, named PHG-UV gel, that
was brought into contact with a phosphate buffer/citric acid
solution at pH 7.0 in the absence or in the presence of mucin at
various concentrations (0.01, 0.1 and 1 wt.-%). Preliminary
dynamic swelling studies have evidenced the occurrence of
an interaction between thePHG-UVgel and the glycoprotein.
This result was confirmed by ATR FT-IR measurements. A
diffusion model using a solution of Ficks’ second law was
employed to determine the diffusion coefficient of water into
PHG-UV gel as a consequence of adsorption and/or interdiffusion
which occur at the PHG-UV gel/mucin solution
interface. Experimental results suggest a potential use of
PHG-UV gel to prepare bioadhesive devices
Recycling Phosphorus from Agricultural Streams: Grey and Green Solutions
Full text linkMany intensively farmed soils show high phosphorus (P) contents compared to the thresholds required for agricultural production; 0.084 Mt of P year−1 is leaving the European terrestrial system. This paper focuses mainly on non-point flows of P and provides an overview of the most promising and sustainable solutions for P recycling, centred on waste materials from agriculture. Given the global shortage of the primary resource of P, its management is critical for its efficient use. Nowadays, wastage and loss at every stage of the P cycle raise concerns about future supplies and especially about the resulting environmental problems, such as the eutrophication of surface water bodies and the reduction of biodiversity. Recovering P costs more than EUR 640 per tonne depending on the type of technique used. The opportunity for P recovery with green and sustainable technology is, therefore, a great challenge for the next years. Waste materials or by-products of agricultural processing have been considered ecologically safe, low-cost, and highly selective with high pollutant adsorption capacities, which would enable sustainable P recovery, both environmentally and economically. A realistic threshold for considering the reuse of P sustainably at the farm level is EUR 320 per tonne
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