Fluorescence analysis of copper(II) and zinc(II) binding behaviour of fulvic acids from pig slurry and amended soils

The evaluation of the mechanisms and extent of interaction of Cu(II) and Zn(II) with fulvic acids (FAs) is of importance for understanding the mobility and bioavailability of these metals in pig slurry (PS)‐amended soils. In this work, a fluorescence titration method and a single site model were used to characterize the interaction of Cu(II) and Zn(II) with FAs isolated from PS, from soils amended with 90 and 150 m³ ha⁻¹ year⁻¹ of PS for 7 years and from the corresponding unamended soil. The binding capacities of FAs and the strengths of metal ion‐FA complexes were larger for Cu(II) than for Zn(II). With respect to the unamended control soil FA, PS‐FA was characterized by smaller binding capacities and stability constants. The binding capacities and affinities of PS‐amended soil FA were intermediate between those of unamended soil FA and PS‐FA, and tended to decrease with increasing amounts of PS applied to soil, thus suggesting a partial incorporation of FA fractions of PS into native soil FA.     

Compositional and functional features of humic acids from organic amendments and amended soils in Minnesota, USA

The use of organic amendments requires an adequate control of the chemical quality of their humic acid (HA)-like fractions and of the effects that these materials may have on the status, quality, chemistry and functions of native soil HAs. In this work, the compositional, functional and structural properties of the HA-like fractions isolated from a liquid swine manure (LSM), a municipal sewage sludge (SS), and two municipal solid waste composts (MSWCs) were evaluated in comparison to those of HAs isolated from three unamended soils and from the corresponding soils amended with LSW, SS, and MSWC at various rates in three field plot experiments conducted in Minnesota, USA. With respect to the unamended soil HAs, the HA-like fractions of the three amendments featured a greater aliphatic character, a marked presence of proteinaceous, S-containing and polysaccharides-like structures, an extended molecular heterogeneity, small organic free radical contents and a small degree of humification. The MSWC-HAs featured a larger degree of humification than LSM-HA and SS-HA. The three amendments affected in different ways and by various extents the compositional, structural and functional properties of soil HAs depending upon the nature, origin and application rate of the amendment. In general, the data obtained suggested that proteinaceous, S-containing and aliphatic structures contained in HA-like fractions of organic amendments were partially incorporated into native soil HAs.     

Enzyme activities in vineyard soils long-term treated with copper-based fungicides

Copper-based fungicides have been applied in vineyard soils for a long time, which has resulted in increasing soil Cu concentration. However, information relating to non-target effects of these fungicides on microorganisms of these soils is scarce. The aim of this study was to determine the potential enzyme activities of vineyard soils in relation to Cu content and evaluate the potential risks of long-term application of Cu-based fungicides. For this purpose, a wide range of soil samples, having different total, exchangeable and bioavailable Cu contents, were collected from six regions of quality wines located in the NW Iberian Peninsula, and the activity of dehydrogenase, β-glucosidase, urease and phosphatase were measured. Overall, the results obtained indicate adverse effects of Cu on dehydrogenase, β-glucosidase and phosphatase activities and an inconsistent effect on urease activity. Threshold Cu concentrations at which changes in the enzyme activities became evident were 150-200 mg total Cu kg⁻¹ and 60-80 mg bioavailable Cu kg⁻¹.     

Investigation of the tuber constituents of maca (Lepidium meyenii Walp.)

Lepidium meyenii, known in South America as maca, has received attention worldwide as a powerful energizer that improves physical and mental conditions and increases fertility. Because of these reports, we investigated the secondary metabolites of the tuber of maca. The methanol extract of the tuber of maca contained, in addition to free sugars and amino acids, the following: uridine, malic acid and its benzoyl derivative, and the glucosinolates, glucotropaeolin and m-methoxyglucotropaeolin. Because glucosinolates and their derived products have received increasing attention due to their biological activities, the occurrence of glucosinolate degradation products in the hexane extract was also investigated, and benzylisothiocyanate and its m-methoxy derivative were isolated. The two glucosinolates were semiquantified by HPLC, and benzylisothiocyanate was semiquantified by GC/MS. The methanol extract of maca tuber also contained (1R,3S)-1-methyltetrahydro-beta-carboline-3-carboxylic acid, a molecule which is reported to exert many activities on the central nervous system.     

Bioaccessibility of tocopherols, carotenoids, and ascorbic acid from milk- and soy-based fruit beverages: influence of food matrix and processing

A study was made of the effect of high-pressure processing (HPP) and thermal treatment (TT) on plant bioactive compounds (tocopherols, carotenoids, and ascorbic acid) in 12 fruit juice-milk beverages and of how the food matrix [whole milk (JW), skimmed milk (JS), and soy milk (JSy)] modulates their bioaccessibility (%). HPP (400 MPa/40 °C/5 min) produced a significant decrease in carotenoid and ascorbic acid bioaccessibility in all three beverages and maintained the bioaccessibility of tocopherols in JW and JS while decreasing it in JSy. TT (90 °C/30 s) produced a significant decrease in tocopherol and carotenoid bioaccessibility in all three beverages and increased the bioaccessibility of ascorbic acid. With regard to the food matrix, α-tocopherol and ascorbic acid bioaccessibility was greatest in JW beverages and lowest in JSy beverages, whereas no significant differences were found among the three beverages in terms of carotenoid bioaccessibility. HPP-treated samples showed higher tocopherol and carotenoid bioaccessibility than TT-treated samples, thus indicating that HPP combined with a milk matrix positively modulates the bioaccessibility of certain types of bioactive components of food, mainly those of a lipophilic nature.     

Determination of ascorbic acid and carotenoids in food commodities by liquid chromatography with mass spectrometry detection

Two methods, one to determine ascorbic acid and one to determine lycopene and beta-carotene, in vegetables and fruits by liquid chromatography coupled with mass spectrometry (LC-MS) have been established. The chromatographic separation of the studied compounds and their MS parameters were optimized to improve selectivity and sensitivity. In both methods, separation was carried out with two coupled columns, first a C(18) and then a dC(18), using as mobile phase 70% methanol (0.005% acetic acid) and 30% acetic acid 0.05% for ascorbic acid determination and a mixture of methanol, tetrahydrofuran, and acetonitrile (60:30:10 v/v/v) for carotenoid analysis in isocratic mode. The molecular ion was selected for the quantification in selective ion monitoring (SIM) mode. Ascorbic acid was detected with electrospray ionization probe (ESI) in negative mode, while chemical ionization atmospheric pressure (APCI) in positive mode was used for the target carotenoids. The methodology for ascorbic acid analysis is based on an extraction with polytron using methanol and a mixture of methaphosphoric acid and acetic acid. Extraction of the carotenoids was carried out with tetrahydrofuran/methanol (1:1) (v/v). The proposed methods were applied, after their corresponding validations, to the analysis of four varieties of tomatoes, tomato in tin enriched and dried tomato, and to the analysis of mango and kiwi fruits, to compare the content in these compounds. Moreover, the influence of the process of freezing and the effect that the manipulation/preservation has in the content of ascorbic acid in tomato have also been studied.     

Adsorption of Graphene Oxide onto Synthetic Fibers: Experimental Conditions

Comparative studies on the adsorption capacity of two synthetic fibers, polyamide (PA 66) and polyester (PET) pre-treated with N-cetylpyridinium chloride (PET-NCPCl), towards graphene oxide (GO) have been carried out. The fiber samples were characterized by scanning electron microscopy (FE-SEM) and Raman spectroscopy. The results of adsorption isotherms, kinetics, and zeta potential determinations as a function of the GO concentration, pH, and temperature show that at a low pH of 2.5 and a high temperature of 323 K, almost 99 % of the 75 mg/l GO solution is adsorbed onto PA 66 and 70 % onto the PET-NCPCl fibers. The interaction should be first attributed to electrostatic forces, also the adsorption data exhibited a good fit to the Freundlich isotherm model and the free energy value of 10 kJ/mol was in the range of physical adsorption, which could suggest that the interaction is driven mainly by physical forces. Due to the increasing development of wastewater treatments based on the GO reactivity with metals and cationic contaminants, synthetic fibers coated with GO could be considered an adsorbent for environmental applications.     

Mapping within-field variability in wheat yield and biomass using remote sensing vegetation indices

Precision Agriculture - This paper explored the ability of remote sensing (RS) and meteorological data to map the variability of yield/biomass in cultivated wheat (Triticum aestivum). The...     

The Impact of Reproductive Technologies on Stallion Mitochondrial Function

The traditional assessment of stallion sperm comprises evaluation of sperm motility and membrane integrity and identification of abnormal morphology of the spermatozoa. More recently, the progressive introduction of flow cytometry is increasing the number of tests available. However, compared with other sperm structures and functions, the evaluation of mitochondria has received less attention in stallion andrology. Recent research indicates that sperm mitochondria are key structures in sperm function suffering major changes during biotechnological procedures such as cryopreservation. In this paper, mitochondrial structure and function will be reviewed in the stallion, when possible specific stallion studies will be discussed, and general findings on mammalian mitochondrial function will be argued when relevant. Especial emphasis will be put on their role as source of reactive oxygen species and in their role regulating sperm lifespan, a possible target to investigate with the aim to improve the quality of frozen–thawed stallion sperm. Later on, the impact of current sperm technologies, principally cryopreservation, on mitochondrial function will be discussed pointing out novel areas of research interest with high potential to improve current sperm technologies.