Search results for "performance"

Extraction of polycyclic aromatic hydrocarbons from cookies: a comparative study of ultrasound and microwave-assisted procedures.

2008

The chromatographic determination of 15 polycyclic aromatic hydrocarbons (PAHs) in cookies has been improved in order to obtain a fast method with a low limit of detection through the combination of microwave-assisted extraction (MAE), oil saponification and solid-phase extraction clean-up before the injection of purified extracts in a C18 201TP52 (5 microm, 250 x 2.1 mm) column. Using acetonitrile-water as mobile phase, with a 50% to 95% w/w acetonitrile gradient for a fixed flow of 0.250 ml min(-1), 15 PAHs were separated in 45 min. The column temperature was maintained at 15 degrees C; and fluorimetric detection was made at a fixed excitation wavelength of 264 nm and emission measurement…

Verbal learning and memory and their associations with brain morphology and illness course in schizophrenia spectrum psychoses.

2012

The California Verbal Learning Test and structural brain imaging were administered to 57 subjects with schizophrenia spectrum disorders and 94 controls in a general population sample. Cases had lower semantic cluster scores. Poorer verbal memory strategies were associated with longer duration of illness and heavier use of antipsychotic medication. After controlling for duration of illness, sex, and total gray matter, poorer verbal memory was associated with lower gray matter volume in the cingulate cortex, juxtapositional lobule, right superior temporal gyrus, and precuneus. After controlling for use of antipsychotic medication, there was an association between higher serial clustering and …

Association between cingulum bundle structure and cognitive performance: an observational study in major depression.

2009

AbstractBackgroundMajor depression can be regarded as a systemic neurobehavioral disorder resulting from dysfunction of the limbic-cortical networks. The cingulum bundle represents a major association fiber tract of those networks. The aim of our study was to determine the association of brain structural tissue markers of the cingulum bundle and cognitive function in patients with major depression.MethodsRegion-of-interest-based analyses of the middle-anterior and middle-posterior cingulum bundle fractional anisotropy (FA) and mean diffusivity (MD) using color-coded diffusion-tensor imaging and neuropsychological assessment in 14 patients with major depression.ResultsFA of the middle-anteri…

Direct optical resolution of trans-dihydrodiol enantiomers of fjord-region polycyclic aromatic hydrocarbons by high-performance liquid chromatography…

1998

Abstract Enantioselective separation of trans -dihydrodiol metabolites of a series of fjord-region polycyclic aromatic hydrocarbons (PAHs), such as benzo[ c ]phenanthrene and dibenzo[ a , l ]pyrene, was evaluated by HPLC using commercially available cellulose-based CSPs as chiral columns. A baseline separation ( R s ≥1.6) with sharp, well-defined peaks of individual enantiomers was attained using cellulose-tris-( N -3,5-dimethylphenylcarbamate) and n -heptane-ethanol (9:1, v/v) as mobile phase. These chromatographic conditions permit a direct, simple and rapid (mostly within 30 min) enantiomeric resolution of PAH dihydrodiols. CD spectra were obtained for all optically pure enantiomers and …

HPLC study on the ‘history’ dependence of gramicidin A conformation in phospholipid model membranes

1989

AbstractA novel HPLC methodology for the study of gramicidin A reconstituted in model membranes has been tested in comparison with circular dichroism data. It is shown that this chromatographic technique not only corroborates most of the recent spectroscopic results but allows one to explain them in terms of mass fractions of different actual conformational species of GA in the phospholipid assemblies. In particular, the dependence of the inserted peptide configuration on the organic solvent and other parameters involved in the ‘history’ of the sample preparation and handling has been analyzed by HPLC in two phospholipid model systems: small unilamellar vesicles and micelles. Moreover, a sl…

Liquid chromatographic–mass spectrometric determination of post-harvest fungicides in citrus fruits

2001

Liquid chromatography (LC)-atmospheric pressure ionisation (API)-mass spectrometry (MS) has been used to determine residues of five fungicides in oranges with a minimum sample cleanup. Atmospheric pressure chemical ionisation (APCI) and electrospray (ES) were compared and both gave similar results in terms of sensitivity and structural information. The main ions were [M+H]+ for carbendazim, imazalil, thiophanate methyl and thiabendazole, and [M+H-C4H9NHCO]+ for benomyl. Samples were extracted with sodium sulphate and ethyl acetate. Although benomyl and thiophanate methyl were transformed through the extraction procedure to carbendazim, the method showed good precision (13%) and recovery (70…

The durability of basalt fibres reinforced polymer (BFRP) panels for cladding

2015

The study focuses on two basalt composite laminate panels for cladding, produced by means of vacuum bagging technique. In particular, unidirectional and random basalt fabrics, with different areal weights, using epoxy resin as matrix, were used. According to the ISO 15686 methodology for the evaluation of durability, samples were subjected to cycles of artificial aging in climatic chamber and outdoor exposure, carrying out mechanical (i.e. quasi-static and dynamic) and calorimetric tests. The results show the effectiveness over time of produced basalt composite laminates and the initial increase of the mechanical performances after the first steps of accelerated aging.

Effect of in-class group clicker-quiz competition on student final exam performance.

2019

The Lecture-Performance: Implementing Performative Pedagogy in Literature Class

2020

In recent years the performative has gained importance within the pedagogical field and has opened new perspectives in educational research. Experience has shown that the integration of performative elements in the learning process allow teachers to involve learners emotionally and cognitively. The present paper deals with a learning experience performed with students in the course “German Literature (2nd language)” at the University of Valencia. From the perspective of Performative Pedagogy, students are asked to carry out a research project and then transfer the acquired knowledge to the theatrical format that must be didactic: a Lecture-Performance. This activity highlights the benefits …

Importance sampling for Lambda-coalescents in the infinitely many sites model

2011

We present and discuss new importance sampling schemes for the approximate computation of the sample probability of observed genetic types in the infinitely many sites model from population genetics. More specifically, we extend the 'classical framework', where genealogies are assumed to be governed by Kingman's coalescent, to the more general class of Lambda-coalescents and develop further Hobolth et. al.'s (2008) idea of deriving importance sampling schemes based on 'compressed genetrees'. The resulting schemes extend earlier work by Griffiths and Tavar\'e (1994), Stephens and Donnelly (2000), Birkner and Blath (2008) and Hobolth et. al. (2008). We conclude with a performance comparison o…