Search results for "Octanes"

Maternal Perfluoroalkyl Substances, Thyroid Hormones, and DIO Genes: A Spanish Cross-sectional Study

2021

Results of studies on perfluoroalkyl substances (PFASs) and thyroid hormones (THs) are heterogeneous, and the mechanisms underlying the action of PFASs to target THs have not been fully characterized. We examined the relation between first-trimester maternal PFAS and TH levels and the role played by polymorphisms in the iodothyronine deiodinase 1 (DIO1) and 2 (DIO2) genes in this association. Our sample comprised 919 pregnant Spanish women (recruitment = 2003-2008) with measurements of perfluorohexanesulfonic acid (PFHxS), perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorononanoic acid (PFNA), thyroid-stimulating hormone (TSH), total triiodothyronine (TT3), and fr…

First-trimester maternal concentrations of polyfluoroalkyl substances and fetal growth throughout pregnancy

2019

Background: Several studies have investigated the possible association between prenatal exposure to perfluoroalkyl substances (PFASs) and birth anthropometry. However, none has assessed fetal size longitudinally. We studied the possible association between PFASs and fetal biometry. Methods: In 1230 mother-child pairs of three cohorts from the Spanish INMA-Project, we analyzed perfluorohexanesulfonic acid (PFHxS), perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) in first-trimester maternal plasma (collection: 2003-2008). We measured abdominal circumference (AC), femur length (FL), biparietal diameter (BPD), and estimated fetal weight (EFW)…

Olefin metathesis reactions with fluorinated substrates, catalysts, and solvents.

2014

Polystyrene nanoparticles in the presence of (ethylene oxide)13(propylene oxide)30(ethylene oxide)13, N,N-dimethyloctylamine-N-oxide and their mixtur…

2008

Polystyrene nanoparticles were synthesized by emulsion polymerization of styrene. They were functionalized using the conventional surfactant N,N-dimethyloctylamine-N-oxide (ODAO), the tri-block copolymer (ethylene oxide)13(propylene oxide)30(ethylene oxide)13 (L64) and their mixtures. To this purpose, dynamic light scattering and calorimetric experiments were carried out and provided information consistent to each other. The L64 adsorption is Langmuir-type in the copolymer dilute regime and generates complex structures at larger concentrations. In the region where ODAO is in the unimeric state, the adsorption process is cooperative leading to hemi-micelle formation at the polystyrene nanopa…

Ellipsoid-shaped superparamagnetic nanoclusters through emulsion electrospinning.

2015

Ellipsoid-shaped nanoclusters composed of single superparamagnetic nanoparticles can be generated by emulsion electrospinning. Stretching and subsequent solvent evaporation of iron oxide loaded emulsion droplets during the emulsion electrospinning process enables the creation of such structures embedded in polymer nanofibers. Dissolution of the polymer fibers yields an aqueous dispersion of the inorganic clusters which are the first example of ellipsoid-shaped superparamagnetic nanoclusters with a high saturation magnetization (∼47 emu g(-1)).

Analysis of perfluorinated compounds in sewage sludge by pressurized solvent extraction followed by liquid chromatography–mass spectrometry

2011

Perfluorinated compounds (PFCs) are widely used in everyday life and one of the main recipients of these compounds is waste water treatment plants (WWTPs). Due to the structure and physicochemical properties of PFCs, these compounds could be redistributed from influent water to sludge. This work reports a new validated protocol for the analysis of 13 perfluorinated acids, 4 perfluorosulfonates and the perfluorooctanesulfonamide. The present work has been focused to develop a sensitive and robust method for the analysis of 18 PFCs in sewage sludge, based on pressurized solvent extraction (PSE) followed by solid phase extraction (SPE) clean-up, analytes separation by liquid chromatography and…

Variability of perfluoroalkyl substance concentrations in pregnant women by socio-demographic and dietary factors in a Spanish birth cohort

2016

Background: Prenatal exposure to perfluoroalkyl substances (PFAS) might affect child health; but maternal determinants of PFAS exposure are unclear. We evaluated the socio-demographic and dietary factors of prenatal PFAS concentrations in a Spanish birth cohort. Methods: We analyzed perfluorohexanesulfonic acid (PFHxS), perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) in 1216 plasma samples collected during the 1ST trimester of pregnancy (2003–2008). We used multivariable linear regressions to assess the geometric mean (GM) ratios of PFAS concentrations by socio-demographic and dietary factors. We used analysis of variance (ANOVA) to asse…

Theoretical calculation of the vibrational spectra of cis-cis-cyclooctadienes in the vapour phase.

2000

The theoretical infrared spectra of 1,3-cis-cis-cyclooctadiene (1,3-COD) and 1,5-cis-cis-cyclooctadiene (1,5-COD), were obtained by ab initio MO calculations at Hartree-Fock level. The results were compared with the available IR experimental spectra of 1,3- and 1,5-COD. The apparent agreement between theoretical and experimental data allows us to exploit two bands, found only in the case of the theoretical spectrum of 1,4-COD, as a tool for identifying 1,4-COD during its synthesis.