Search results for " Phase"

Ab Initio Phase Diagram of Chromium to 2.5 TPa

2022

Chromium possesses remarkable physical properties such as hardness and corrosion resistance. Chromium is also a very important geophysical material as it is assumed that lighter Cr isotopes were dissolved in the Earth’s molten core during the planet’s formation, which makes Cr one of the main constituents of the Earth’s core. Unfortunately, Cr has remained one of the least studied 3d transition metals. In a very recent combined experimental and theoretical study (Anzellini et al., Scientific Reports, 2022), the equation of state and melting curve of chromium were studied to 150 GPa, and it was determined that the ambient body-centered cubic (bcc) phase of crystalline Cr re…

Sensitive determination of polycyclic aromatic hydrocarbons in water samples using monolithic capillary solid-phase extraction and on-line thermal de…

2011

A methacrylate-based monolithic capillary column has been evaluated for the preconcentration of polycyclic aromatic hydrocarbons (PAHs) from environmental water samples. For this purpose, the monolyte was in situ synthesized in a 6cm×0.32mm id fused-silica capillary. The microextraction unit was fitted to a micro-HPLC pump to pass 10mL of sample. The isolated pollutants were eluted by means of 10μL of methanol, the organic phase being directly collected in a specific interface that can be fitted to the injection port of the gas chromatograph without modification. The interface allows the on-line thermal desorption of the PAHs, avoiding the dilution and providing enough sensitivity to reach …

SYNTHESIS AND CHARACTERISATION OF NEW AZOLE BUILDING BLOCKS FOR FUNCTIONAL IONIC SYSTEMS

The synthesis of a series of 27 salts based on 5-(4-(alkyloxy)phenyl)-1,4-dimethyl-3-(perfluoroalkyl)-1,2,4-triazol-4-ium structures, differing in the length of the alkyl and perfluoroalkyl chains, as well as in the counter ions is reported. Some properties of this new family of salts as perspective liquid-crystalline ionic liquids (LC-ILs) are described and the influence of the varying moieties in the modulation of the properties is discussed.

Analysis of 18 perfluorinated compounds in river waters: Comparison of high performance liquid chromatography–tandem mass spectrometry, ultra-high-pe…

2012

In this work, the performance of ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) and capillary liquid chromatography-mass spectrometry (CLC-MS) has been studied for the analysis of eighteen perfluorinated compounds in water samples. UHPLC-MS/MS and CLC-MS analysis were carried out using a Zorbax C-18 column (50 mm × 2.1 mm, 1.8 μm) and a Zorbax SB-C18 column (150 mm × 0.5 mm, 3.5 μm), respectively, in gradient elution mode with a mobile phase of ammonium formate and methanol. Both techniques were compared with conventional LC-MS/MS in terms of speed, sensitivity, selectivity and resolution. Water samples were extracted by solid phase extraction (SPE). Mea…

Distribution and fate of perfluoroalkyl substances in Mediterranean Spanish sewage treatment plants.

2014

The concentrations of 21 perfluoroalkyl substances (PFASs: C4-C14, C16, C18 carboxylates, C4, C6-C8 and C10 sulfonates and C8 sulfonamide) were determined in influent, effluent and sludge from 16 different sewage treatment plants (STPs) located in the Ebro (6), Guadalquivir (5), Jucar (2) and Llobregat (3) Rivers, in two consecutive years (2010 and 2011). The analytes were extracted by solid phase extraction (SPE) and determined by Liquid Chromatography triple Quadrupole Mass Spectrometer (LC-QqQ-MS). All samples, except two sludges from Guadalquivir River STPs, were contaminated with at least one PFAS. Perfluorobutanoate (PFBA), perfluoropentanoate (PFPeA) and perfluorooctane sulfonate (L-…

Endocrine and ovarian response after a 2-day controlled suckling and eCG treatment in lactating rabbit does.

2006

Synchronization methods are used to obtain higher fertility when artificial insemination (AI) is applied to lactating rabbit does. The most common methods are eCG administration or temporary doe–litter separation. Nevertheless, drawbacks have been reported, such as negative side effects of hormonal treatment in the doe and low litter growth due to absence of suckling, respectively. Recently, improved reproductive performance (without visible consequences on young rabbit growth), has been obtained by applying a 2-day controlled nursing method before AI, by allowing for a 10 min nursing of the litter 24 h of separation. The present study was undertaken to examine the pituitary (PRL, LH, FSH) …

Reproducibility and relative validity of a newly developed web-based food-frequency questionnaire for assessment of preconception diet

2019

Abstract Background The importance of diet and nutrition during preconception age is a window of opportunity to promote future parental and transgenerational health. As a sub-study to a large Norwegian study, ‘Diet today – health of tomorrow’, a food-frequency questionnaire (FFQ) was developed to assess diet during the preconception phase in young adults aged 20 – 30 years and in this paper we report the reproducibility and relative validity of this questionnaire. Methods The FFQ was developed from an existing FFQ validated in adolescents. Participants were recruited on social media and at a university. Reproducibility was assessed by comparing the test and retest of the FFQ. Relative valid…

On the Solid Bonding Phenomena in Linear Friction Welding and Accumulative Roll Bonding Processes: Numerical Simulation Insights

2015

Solid Bonding based welding processes allow to obtain defect free joints with low residual stress and low distortion. However, the engineering and optimization of solid bonding processes is difficult and requires a large number of time and cost consuming test trials. In this way, proper numerical models are essential tools permitting effective process design. The aim of this research was the comparison of the material process conditions during two different manufacturing processes taking advantage of the same metallurgical phenomenon, namely solid bonding. Linear Friction Welding, used to weld non-axisymmetric components and Accumulative Roll Bonding, used to increase the mechanical propert…

Evaluation of methods aimed at complete removal of template from molecularly imprinted polymers

2001

Polymers imprinted with clenbuterol were used to study the influence of various post-polymerization treatments [e.g., thermal annealing, microwave assisted extraction (MAE), Soxhlet extraction and supercritical fluid template desorption] on the bleeding of residual template. The aim of the study was to reduce the bleeding to levels that would allow the use of the materials as affinity phases for extraction of clenbuterol from bovine urine at concentrations below 1 ng ml−1. After treatment, the clenbuterol imprinted polymers were packed into solid-phase extraction columns and the bleeding was estimated by quantifying the amount of template released in 10 ml of methanol–acetic acid (9 + 1 v/v…

Controlling laser assisted radiative recombination with few-cycle laser pulses

2006

We report on the radiative recombination of a free electron with a hydrogenic ion in the presence of a few-cycle pulses. It has been shown that the main features of the emission spectra may be described in the framework of a semiclassical model in which the recombination is viewed as a two-step process. The spectra width of the emitted photon energy is practically confined in a range of values in which the emission is classically allowed. Moreover, it has been found that spectra width can be controlled by varying the carrier envelope phase and/or the pulse peak intensity.