Effects of discrete energy and helicity conservation in numerical simulations of helical turbulence

Helicity is the scalar product between velocity and vorticity and, just like energy, its integral is an in-viscid invariant of the three-dimensional incompressible Navier-Stokes equations. However, space-and time-discretization methods typically corrupt this property, leading to violation of the inviscid conservation principles. This work investigates the discrete helicity conservation properties of spectral and finite-differencing methods, in relation to the form employed for the convective term. Effects due to Runge-Kutta time-advancement schemes are also taken into consideration in the analysis. The theoretical results are proved against inviscid numerical simulations, while a scale-dependent analysis of energy, helicity and their non-linear transfers is performed to further characterize the discretization errors of the different forms in forced helical turbulence simulations

Data_Sheet_1_Human biomonitoring of neonicotinoid exposures: case studies after the use of a spray-agent to ornamental plants and a topical medication to pets.PDF

Acetamiprid (ACE) and imidacloprid (IMI) are insecticides of global importance and are used as spray and watering agents for ornamental plants to control biting and sucking insects or as topical medications on pets to remove and control fleas. Human biomonitoring data on ACE and IMI exposures when applying these products are limited. We investigated exposures to ACE and IMI in male volunteers after the domestic application of either an ACE-containing agent or an IMI-containing spot-on medication. Complete and consecutive urine samples were collected for up to 56 h after application. Urine samples were analyzed for ACE, IMI, and their respective metabolites (N-desmethyl-ACE, IMI-olefin, and sum of 4−/5-hydroxy-IMI) by liquid chromatography–tandem mass spectrometry. Fairly uniform concentrations of N-desmethyl-ACE could be observed before and after orchid treatment, so that an ACE exposure associated with orchid treatment can most likely be excluded. In contrast, after the application of the IMI-containing medication, elevated concentrations of IMI, 4−/5-hydroxy-IMI, and IMI-olefin were quantified in urine samples post-20 h with maximum concentrations of 3.1, 14.9, and 8.0 μg/g creatinine, respectively, well above general background levels. Nevertheless, the IMI intake (10.6 μg/kg bw), calculated from the excreted amounts, was around five times below the current European acceptable daily intake. Based on the case results here, household exposures to ACE and IMI after spray treatment of ornamental plants and anti-flea treatment of dogs can be regarded as low and safe. However, people regularly applying neonicotinoid-containing formulations, such as professional gardeners and employees in animal shelters, should be studied in more detail.</p

High-Performance Liquid Chromatography–Mass Spectrometry Profiling of Phenolic Compounds for Evaluation of Olive Oil Bitterness and Pungency

Bitterness and pungency are important parameters for olive oil quality. Therefore, two instrumental methods for evaluation of these taste attributes were developed. The first one is based on the photometric measurement of total phenolic compounds content, whereas the second one is based on the semiquantitative evaluation of hydrophilic compounds by high-performance liquid chromatography–mass spectrometry (HPLC-MS). Evaluation of total phenolic compounds content was performed by a modified method for the determination of the <i>K</i>₂₂₅ value using a more specific detection based on the pH value dependency of absorbance coefficients of phenols at λ = 274 nm. The latter method was not suitable for correct prediction, because no significant correlation between bitterness/pungency and total phenolic compounds content could be found. For the second method, areas of 25 peaks detected in 54 olive oil samples by a HPLC-MS profiling method were correlated with the bitterness and pungency by partial least-squares regression. Six compounds (oleuropein aglycon, ligstroside aglycon, decarboxymethyl oleuropein aglycon, decarboxymethyl ligstroside aglycon, elenolic acid, and elenolic acid methyl ester) show high correlations to bitterness and pungency. The computed model using these six compounds was able to predict bitterness and pungency of olive oil in the error margin of the sensory evaluation (±0.5) for most of the samples

Lipidomic and Metallomic Alteration of Caenorhabditis elegans after Acute and Chronic Manganese, Iron, and Zinc Exposure with a Link to Neurodegenerative Disorders

Parkinson’s disease (PD) progresses with the loss of dopaminergic neurons in the substantia nigra pars compacta region of the brain. The superior mechanisms and the cause of this specific localized neurodegeneration is currently unknown. However, experimental evidence indicates a link between PD progression and reactive oxygen species with imbalanced metal homeostasis. Wild-type Caenorhabditis elegans exposed to redox-active metals was used as the model organism to study cellular response to imbalanced metal homeostasis linked to neurodegenerative diseases. Using modern hyphenated techniques such as capillary electrophoresis coupled to inductively coupled plasma mass spectrometry and ultrahigh-performance liquid chromatography mass spectrometry, alterations in the lipidome and metallome were determined in vivo. In contrast to iron, most of the absorbed zinc and manganese were loosely bound. We observed changes in the phospholipid composition for acute iron and manganese exposures, as well as chronic zinc exposure. Furthermore, we focused on the mitochondrial membrane alteration due to its importance in neuronal function. However, significant changes in the inner mitochondrial membrane by determination of cardiolipin species could only be observed for acute iron exposure. These results indicate different intracellular sites of local ROS generation, depending on the redox active metal. Our study combines metallomic and lipidomic alterations as the cause and consequence to enlighten intracellular mechanisms in vivo, associated with PD progression. The mass spectrometry raw data have been deposited to the MassIVE database (https://massive.ucsd.edu) with the identifier MSV000090796 and 10.25345/C51J97C8F

Determination of Urinary Metabolites of the Emerging UV Filter Octocrylene by Online-SPE-LC-MS/MS

Octocrylene (OC) is an emerging UV filter, which is used in the majority of sunscreens as well as other personal care products (PCP) and consumer products. Its presence in various environmental matrices has been reported. However, information on the internal OC exposure in humans is not available, due to the lack of appropriate biomarkers of exposure and analytical methods. Here, we describe a rugged, precise, and accurate analytical method for the determination of three OC metabolites (ester hydrolysis and alkyl chain oxidation products) in human urine by stable isotope dilution analysis. Urine samples are incubated with β-glucuronidase (<i>E. coli</i> K12) and then analyzed by liquid chromatography-electrospray ionization-triple quadrupole-tandem mass spectrometry with online turbulent flow chromatography for sample cleanup and analyte enrichment (online-SPE-LC-MS/MS). Syntheses of analytical standards, including deuterium-labeled internal standards, are also described. In a pilot study, we investigated the applicability of the metabolites as biomarkers of exposure in urine samples from the general population (<i>n</i> = 35). OC metabolites were detected in 91% of the samples, with the highest concentrations for three individuals having used sunscreen within 5 days prior to sample collection. We will apply the method in future human biomonitoring studies for OC exposure and risk assessment

MOESM1 of Designer rhamnolipids by reduction of congener diversity: production and characterization

Additional file 1. Compilation of extra information for better comprehension of the contents of the study. The file contains a more detailed description of some methods, as well as some additional figures for the presented results

Localization of five new candidate proteins to human peroxisomes.

<p>Huh7 cells were transfected with plasmids for expression of DsRed fusion proteins of ISOC1, HSDL2, MDH1, LDHA and ADH1A as well as EGFP-SKL as peroxisomal marker. Images from the left to right: EGFP-SKL (green), candidate fusion protein (red), merge. Images were assembled from z-projections; the scale bar represents 20 µm.</p

Quantitative protein profiling to identify new candidate proteins of human liver peroxisomes.

<p>Protein profiles were established as an average of normalized peptide abundances and correlated to the mean peroxisomal profile by statistical analysis using the χ²-method. (A) Mean peroxisomal profile. (B-D) Profiles of peroxisomal 3,2-trans-enoyl-CoA isomerase and catalase as well as the mitochondrial O subunit of ATP synthase. (E, F) Profiles of ISOC1 and HSDL2 identified as new candidate proteins of human liver peroxisomes.</p

ISOC1 and HSDL2 partially colocalize with human liver peroxisomes.

<p>Nycodenz gradient fractions of human liver were subjected to SDS-PAGE followed by immunoblot analysis using antibodies against the peroxisomal candidate proteins HSDL2 and ISOC1 as well as catalase (peroxisomal marker) and the voltage-dependent anion channel VDAC (mitochondrial marker). In addition to its partial localization to peroxisomes, HSDL2 was found to localize to mitochondria.</p

New candidate proteins of human liver peroxisomes studied by confocal microscopy.

<p>Human liver peroxisomes were enriched by differential and Nycodenz gradient centrifugation (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0057395#pone.0057395.s001" target="_blank">Fig. S1</a>). Ten consecutive gradient fractions were quantitatively analyzed by high resolution MS to establish abundance profiles of 314 proteins (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0057395#pone-0057395-g002" target="_blank">Fig. 2</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0057395#pone.0057395.s011" target="_blank">Table S4</a>). Using a supervised statistical approach, the χ²-method, new candidates of human liver peroxisomes were identified with an Euclidian distance (Ρ-value) of ≤1.02. All candidate proteins were shown to associate with human peroxisomes by colocalization studies using confocal microscopy in Huh7 (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0057395#pone-0057395-g003" target="_blank">Fig. 3</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0057395#pone.0057395.s002" target="_blank">Fig. S2</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0057395#pone.0057395.s006" target="_blank">S6</a>). Sequences of candidate proteins were analyzed for potential peroxisomal targeting signals (PTS) 1 and 2 using both PSORT <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0057395#pone.0057395-Nakai1" target="_blank">[31]</a> and the PTS1 predictor <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0057395#pone.0057395-Edqvist1" target="_blank">[35]</a>.</p