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There were multiple errors introduced in Figure 1 during the preparation of this manuscript for publication. Please view the correct Figure 1 here: thumbnail Download: * PPT PowerPoint slide * PNG larger image * TIFF original image Figures Citation: Fackrell K, Edmondson-Jones M, Hall DA (2013) Correction: A Controlled Approach to the Emotional Dilution of the Stroop Effect.

Toute politique publique est caractérisée par une stratégie, des moyens institutionnels, financiers, des instruments opérationnels, des règles à respecter faisant l’objet de sanctions. Son efficacité peut se mesurer à l’un de ses paramètres. La loi de 1992 a constitué une étape significative dans l’approfondissement du droit de l’eau avec l’instauration d’un cadre institutionnel et une répartition des compétences pour le moins clarifiée. Ce schéma a été quelque peu précisé, complété, donnant ainsi à la politique de l’eau une visibilité reconnue par l’ensemble des acteurs, une sorte d’étape complémentaire. Puis, de simplification, harmonisation et adaptation en réformes, de modulation sous la pression des lobbies, au rôle controversé dévolu à l’État, les évolutions intervenues au cours des dernières années conduisent à une réelle complexité, présentant le caractère d’un inextricable labyrinthe, une forme d’art de la complexité. [...]

In this study, we demonstrate the applicability of nitrogen microwave inductively coupled atmospheric pressure mass spectrometry (MICAP-MS) for Ca, Fe, and Se quantification in human serum using isotope dilution (ID) analysis. The matrix tolerance of MICAP-MS in Na matrix was investigated, revealing that high Na levels can suppress the signal intensity. This suppression is likely due to the plasma loading and the space charge effect. Moreover, 40Ca and 44Ca isotopic fractionation was noted at elevated Na concentration. Nine certified serum samples were analyzed using both external calibration and ID analysis. Overestimation of Cr, Zn, As, and Se was found in the results of external calibration, which might result from C-induced polyatomic interference and signal enhancement, respectively. Further investigations performed with methanol showed a similar enhancement effect for Zn, As, and Se, potentially supporting this assumption. The mass concentrations determined with ID analysis show metrological compatibility with the reference values, indicating that MICAP-MS combined with ID analysis can be a promising method for precise Ca, Fe, and Se determination. Moreover, this combination reduces the influence of matrix effects, broadening the applicability of MICAP-MS for samples with complex matrixes.

Accurate measurements of plasma mycophenolic acid (MPA) are essential for therapeutic drug monitoring in transplant recipients and autoimmune diseases. The performance of plasma mycophenolic acid routine methods remains highly variable that calls for a candidate reference measurement procedure (cRMP) to improve the standardization of plasma mycophenolic acid measurements. In this study, sample preparation was based on protein precipitation with methanol followed by further dilution. The mycophenolic acid was quantified by the isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC–MS/MS) with electrospray ionization in positive ion mode. According to the Clinical and Laboratory Standards Institute (CLSI) documents C62-A and C50-A, the basic analytical performance of the candidate reference method was verified, such as linearity, limit of quantification, matrix effect, precision, accuracy, and uncertainty. Moreover, the candidate reference measurement procedure was compared with the routine liquid chromatography-tandem mass spectrometry (LC–MS/MS) method in a clinical laboratory. Based on the data, the mycophenolic acid in human plasma was well detected by ID-LC–MS/MS. No apparent interferences were found with the mycophenolic acid measurement. The calibration curve for the mycophenolic acid was linear in the concentration range of 0.1–50 μg/mL with a correlation coefficient of 0.9999 under the optimum experimental conditions. This method was sensitive because the low limit of quantitation (LOQ) was 0.05 μg/mL. The recoveries of MPA were 98.11–98.95%. The intra-day and inter-day coefficients of variations (CV) of our method were ≤ 1.53% and ≤ 0.51%, respectively. No obvious matrix effect was observed. There was a good correlation between this method and the clinical routine LC–MS/MS method. To sum up, we established and validated a reliable plasma MPA method using ID-LC/MS/MS. The desirable accuracy and precision of this method enable it to serve as a promising cRMP to improve the standardization for plasma MPA routine measurements. Graphical Abstract

The influence of the roasting procedure on the composition of key aroma compounds in fermented Forastero cocoa beans was investigated. For this purpose, the volatile fractions from the unroasted, fermented and the roasted cocoa were isolated by extraction/SAFE distillation, and the odour-active constituents were characterised by gas chromatography–olfactometry in combination with an aroma extract dilution analysis. A total of 41 aroma compounds in the flavour dilution (FD) factor range of 2–8192 were identified in the unroasted and 42 compounds with FD factors of 2–8192 in the roasted cocoa beans. Qualitatively, the set of aroma compounds was nearly identical in both samples; however, differences in the flavour dilution factors were observed. 2- and 3-Methyl butanoic acid (sweaty) and acetic acid (vinegar-like, sour) showed the highest FD factors in the unroasted beans, while 3-methylbutanal (malty), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (caramel-like) and 2- and 3-methyl butanoic acid (sweaty) were detectable by GC/O in the highest dilutions in the roasted seeds. Quantitation of the most odour-active compounds by means of stable isotope dilution assays, followed by calculation of odour activity values (OAV, ratio of concentration to odour threshold), revealed concentrations above the threshold level for 20 compounds in the unroasted and 24 compounds in the roasted beans. The roasting procedure led to a strong increase, in particular, in the concentrations of the two Strecker aldehydes 3-methylbutanal (malty) and phenylacetaldehyde (honey-like) as well as 4-hydroxy-2,5-dimethyl-3(2H)-furanone (caramel-like).

This study examines the potential, magnitude, and causes of enhanced biological N₂ fixation (BNF) by common beans (Phaseolus vulgaris L.) through bio-char additions (charcoal, biomass-derived black carbon). Bio-char was added at 0, 30, 60, and 90 g kg-¹ soil, and BNF was determined using the isotope dilution method after adding ¹⁵N-enriched ammonium sulfate to a Typic Haplustox cropped to a potentially nodulating bean variety (CIAT BAT 477) in comparison to its non-nodulating isoline (BAT 477NN), both inoculated with effective Rhizobium strains. The proportion of fixed N increased from 50% without bio-char additions to 72% with 90 g kg-¹ bio-char added. While total N derived from the atmosphere (NdfA) significantly increased by 49 and 78% with 30 and 60 g kg-¹ bio-char added to soil, respectively, NdfA decreased to 30% above the control with 90 g kg-¹ due to low total biomass production and N uptake. The primary reason for the higher BNF with bio-char additions was the greater B and Mo availability, whereas greater K, Ca, and P availability, as well as higher pH and lower N availability and Al saturation, may have contributed to a lesser extent. Enhanced mycorrhizal infections of roots were not found to contribute to better nutrient uptake and BNF. Bean yield increased by 46% and biomass production by 39% over the control at 90 and 60 g kg-¹ bio-char, respectively. However, biomass production and total N uptake decreased when bio-char applications were increased to 90 g kg-¹. Soil N uptake by N-fixing beans decreased by 14, 17, and 50% when 30, 60, and 90 g kg-¹ bio-char were added to soil, whereas the C/N ratios increased from 16 to 23.7, 28, and 35, respectively. Results demonstrate the potential of bio-char applications to improve N input into agroecosystems while pointing out the needs for long-term field studies to better understand the effects of bio-char on BNF.

Aims To study nitrogen contribution to cucumber derived from nitrogen fixation of Paenibacillus polymyxa WLY78. Methods The nif gene cluster deletion mutant (Δ nifB-V ) of Paenibacillus polymyxa WLY78 was constructed by a homologous recombination method. The effects of plant-growth promotion were investigated by greenhouse experiments. The nitrogen fixation contribution was estimated by 15 N isotope dilution method (also being called the 15 N natural abundance technique). Results Deletion of nif gene cluster of P. polymyxa WLY78 resulted in complete loss of nitrogenase activity. Greenhouse experiments showed that inoculation with P. polymyxa WLY78 could significantly enhance the lengths and dry weights of cucumber roots and shoots, but inoculation with Δ nifB-V mutant could not. 15 N isotope dilution experiments showed that cucumber plants derive 25.93% nitrogen from nitrogen fixation performed by P. polymyxa WLY78, but the Δ nifB-V mutant nearly could not provide nitrogen for plant growth. Conclusions This present study demonstrated that nitrogen fixation performed by P. polymyxa WLY78 contributes to plant growth.

Background and aims Nitrogen (N) mineralization and immobilization are two important N biogeochemical processes in estuarine and coastal sediments. However, the changes of those two processes in sediment following Spartina alterniflora (S. alterniflora) invasions into mangrove wetlands under aerobic and anaerobic conditions remain limited. Methods We used a 15 N stable isotope dilution technique to investigate sediment gross N mineralization (GNM) and NH 4 + immobilization (GAI) under aerobic and anaerobic conditions in mangrove communities, mangrove communities mixed with S. alterniflora , and pure S. alterniflora communities in the Zhangjiang Estuary, China. Results GNM and GAI rates varied spatially and seasonally. Summer N mineralization and immobilization rates under aerobic and anaerobic conditions were both significantly higher than those in winter, and the high rates were observed mainly in mangrove sediments and decreased with S. alterniflora invasion. GNM rates in aerobic conditions were significantly higher than those in anaerobic conditions, while GAI rates in aerobic conditions were less than those in anaerobic conditions. GNM and GAI rates were related closely to temperature, water content and organic matter. S. alterniflora invasion can weaken GNM and GAI rates by reducing organic matter accumulation, and S. alterniflora invasion could have reduced sediment N mineralization (2.10 × 10 3 t N yr −1 ) and immobilization (1.46 × 10 3 t N yr −1 ) in mangrove wetlands of China from 1980 to 2020. Conclusions Our results highlight the importance of S. alterniflora invasion and hydrological conditions in controlling N mineralization and immobilization processes in mangrove sediments and are essential for the evaluation of N-balance in this N-limited ecosystem.

Previous methods for vitamin B12 (B12) analysis have extensively used cyanidation conversion with the intention of converting all cobalamins to cyanocobalamin (CNCbl) for total B12 determination. This approach has been favored for its advantages in reducing the number of analytes, increasing analyte concentration, and improving analyte stability. However, the present study revealed underlying limitations associated with this approach. First, a stable isotope dilution assay (SIDA) determining total B12 as CNCbl after cyanidation conversion (conversion SIDA method) was developed. Method validation demonstrated good sensitivity, recovery, accuracy, and reproducibility for the target analyte CNCbl. However, subsequent application of the conversion method to real meat samples showed incomplete conversions of cobalamins. These inconsistencies revealed day-to-day variability and reliability challenges associated with the cyanidation process. It was not possible to identify this issue during method validation as CNCbl was spiked as the sole analyte and it requires no further cyanidation conversion. The application of LC-MS/MS enabled the detection of trace amounts of unconverted cobalamins. Nevertheless, this approach remains restricted by instrument sensitivity and stability as well as the performance of immunoaffinity purification for different vitamers. Further development of a reliable monitoring method is a prerequisite for further optimization of the cyanidation process. However, significant improvements of analytical instrumentation in terms of sensitivity and stability are required to overcome the current limitations. Graphical abstract

An isotope dilution mass spectrometry (IDMS) method that involves peptide-based protein analysis was developed to accurately quantify insulin. In this study, a signature peptide (GFFYTPK) obtained from tryptic digestion of insulin was selected as a surrogate for insulin. Then, the optimal conditions for signature peptide analysis through mass spectrometry detection and enzymatic digestion were determined. The analytical performance of this method was assessed and validated using porcine insulin-certified reference material. The linear range of the insulin calibration curve ranged from 0.05 ~ 2 mass ratios, with recoveries ranging from 96.15 to approximately 101.15%. The limit of detection was 0.19 ng/mL, and the limit of quantification was 0.63 ng/mL. The quantitative results corresponded well with a certified value that was obtained from measuring a porcine insulin reference material with amino acid-based IDMS. In addition, the target peptide GFFYTPK can be found in other species of insulin. This method was also applied for the quantification of human insulin-certified reference material. Finally, we applied the method to quantify the concentrations of simulated serum insulin. These findings suggested that this signature peptide-based IDMS approach can accurately quantify insulin levels, can assign a certified value to insulin reference materials, and has the potential to quantify serum insulin with traceable measurements.