Search results for "Yle"
showing 10 items of 5917 documents
Substance Use in Early and Middle Adolescence. The Role of Academic Efficacy and Parenting
2019
espanolLos objetivos de esta investigacion son analizar la relacion del consumo de sustancias con el estilo de crianza de los padres y la percepcion de eficacia academica por parte de los adolescentes, estudiar la diferente contribucion de estos factores a la prediccion del consumo de sustancias en la adolescencia y observar la funcion de la autoeficacia academica en la relacion entre el estilo de crianza y el consumo de sustancias en la adolescencia. Participaron 762 adolescentes (53% hombres), de edades comprendidas entre los 12 y los 16 anos (M = 13.66, DT = 1.34). La muestra se selecciono con criterios probabilisticos por conglomerados, atendiendo al tipo de centro (educacion secundaria…
Täpläravun (Pacifastacus leniusculus) vaikutus särjen (Rutilus rutilus) loisiin Päijänteellä
2013
Täplärapu (Pacifastacus leniusculus) on Suomen vesistöissä verrattain uusi vieraslaji, joka leviää sekä suunnitelluin istutuksin että suunnittelematta uusille alueille. Täplärapu on alun perin tuotu Suomeen korvaamaan rapuruton turmelemia jokirapukantoja, mutta sitä on istutettu myös alueille, joissa ei alkuperäistä rapukantaa ole aiemmin ollut. Kotoperäiseen jokirapuun verrattuna täplärapu on paitsi vastustuskykyisempi rapurutolle, myös nopeampi kasvamaan ja lisääntymään. Täplärapu kasvaa jokirapua suuremmaksi ja on luonteeltaan aggressiivisempi. Vieraslajina täplärapu voi muuttaa uuden elinympäristön rakennetta ja toimintaa. Täplärapu käyttää ravintonaan muun muassa selkärangattomia pohja…
Producing SI-traceable reference values for Cd, Cr and Pb amount contents in polyethylene samples from the Polymer Elemental Reference Material (PERM…
2000
The present paper describes the certification of the amount content of Cd, Cr and Pb in two different polyethylene materials within the third phase of the Polyethylene Elemental Reference Material (PERM) project. The analytical procedure to establish the reference values for Cd, Cr and Pb amount contents in these materials is based on isotope dilution mass spectrometry used as a primary method of measurement. Cd and Pb were measured with inductively coupled plasma-mass spectrometry and Cr with positive thermal ionization-mass spectrometry. The decomposition of the polymer matrix was carried out using a high pressure asher. Reference values for amount content, traceable to the SI-system, hav…
Interpretive optimisation strategy applied to the isocratic separation of phenols by reversed-phase liquid chromatography with acetonitrile–water and…
2000
An optimisation protocol is presented for the resolution of complex mixtures in isocratic RPLC with binary mobile phases of organic solvent and water, which is based on the prediction of peak position and shape of the individual compounds. A good description of the retention was achieved through the application of statistical weights to the widely used linear or quadratic relationships between the logarithm of the retention factor (log k) and the organic solvent concentration in the mobile phase. The maximisation of the product of peak purities for each compound is shown as a competitive resolution strategy versus the worst value of a selectivity parameter. Peak purities allow one to associ…
Characterization of particle morphology of biochanin A molecularly imprinted polymers and their properties as a potential sorbent for solid-phase ext…
2014
Abstract Molecularly imprinted polymers (MIPs) with biochanin A as a template were obtained using a bulk polymerization with non-covalent imprinting approach. The polymers were prepared in acetonitrile as porogen, using ethylene glycol dimethacrylate (EDMA) as cross-linking agent. The synthesis, with an application of 1′,1′-azobis(cyclohexanecarbonitrile) (ACHN) as an initiator, has been performed thermally. During the synthesis process the effect of different functional monomers such as methacrylic acid (MAA), acrylamide (AA) and 4-vinylpyridine (4-VP) was investigated. The application of nitrogen sorption porosimetry, scanning electron microscopy (SEM), and Fourier transform infrared spec…
Assisted baseline subtraction in complex chromatograms using the BEADS algorithm.
2017
The data processing step of complex signals in high-performance liquid chromatography may constitute a bottleneck to obtain significant information from chromatograms. Data pre-processing should be preferably done with little (or no) user supervision, for a maximal benefit and highest speed. In this work, a tool for the configuration of a state-of-the-art baseline subtraction algorithm, called BEADS (Baseline Estimation And Denoising using Sparsity) is developed and verified. A quality criterion based on the measurement of the autocorrelation level was designed to select the most suitable working parameters to obtain the best baseline. The use of a log transformation of the signal attenuate…
Sample Preparation Improvement in Polycyclic Aromatic Hydrocarbons Determination in Olive Oils by Gel Permeation Chromatography and Liquid Chromatogr…
2005
Abstract The determination of 15 polycyclic aromatic hydrocarbons (PAHs) in olive oil samples has been improved in order to obtain a fast methodology with a low limit of detection through the combination of liquid–liquid extraction with acetonitrile and preparative gel permeation chromatography (GPC) prior to the injection of purified extracts into a C18 column. Acetonitrile–water was used as the mobile phase with a gradient from 50 to 95%, w/w, acetonitrile in 30 min. The oven temperature was maintained at 15°C, and fluorometric detection was made at a fixed excitation wavelength of 264 nm and variable, optimal emission wavelength for each analyte ranging from 352 nm for 11-H-benzo(b)fluor…
Regeneration of herbicide-tolerant black locust transgenic plants by SAAT
2003
A protocol based on SAAT (sonication-assisted Agrobacterium-mediated transformation) has been developed to obtain herbicide-resistant transgenic black locust (Robinia pseudoacacia L.) plants. Cotyledon explants were co-cultivated with Agrobacterium AGL1 strain carrying the pTAB16 plasmid (bar and gusA genes). The effects of bacterial concentration (OD550 of 0.3, 0.6, 0.8) and method of infection (sonication vs immersion) on bacterial delivery were determined by assaying cotyledons for transient beta-glucuronidase expression 3 days after infection. SAAT increases transient expression efficiency especially at an OD550 of 0.6. After determining bacterial concentration and infection method, oth…
Double Thermoresponsive Block Copolymers Featuring a Biotin End Group
2010
A poly(oligo(ethylene glycol) monomethyl ether methacrylate)-block-poly(N-isopropyl methacrylamide) (POEGMA-b-PNIPMAM) block copolymer with a biotin end group on the PNIPMAM block as a biotarget was synthesized as a model system for temperature-controlled polymer immobilization. The synthesis was based on RAFT polymerization followed by postpolymerization modification of an activated ester precursor block and an exchange of the dithioester end group within one step. NMR, differential scanning calorimetry (DSC), dynamic light scattering (DLS), and turbidimetry measurements were performed to investigate the stimulus-responsive properties. The double thermoresponsive POEGMA-b-PNIPMAM with biot…
Amphotropic Ionomers by Attachment of Secondary Amines to a Reactive Ester Polymer
2004
We report on the synthesis of polyacrylamides that were prepared by the reaction of a reactive ester polymer with a mesogen-containing secondary amine and N-methyl-piperazine. As the polymers do not form hydrogen bonds near the amide groups, their mobility is significantly higher than that of poly(N-monoalkylacrylamides). The initially nonionic polymer shows no liquid-crystalline behavior in bulk and in mixture with ethylene glycol. This is due to the low polarity difference between the different side chains. The polarity difference can be increased by protonation or quarter-nization of the tertiary amino groups, and liquid-crystalline behavior is observed. The self-assembly multilayer buil…