Search results for "ample"
showing 10 items of 2398 documents
Sensitive Screening of New Psychoactive Substances in Serum Using Liquid Chromatography-Quadrupole Time-of-Flight Mass Spectrometry.
2021
Abstract Analysis of new psychoactive substances (NPS) still poses a challenge for many institutions due to the number of available substances and the constantly changing drug market. Both new and well-known substances keep appearing and disappearing on the market, making it hard to adapt analytical methods in a timely manner. In this study we developed a qualitative screening approach for serum samples by means of liquid chromatography--quadrupole time-of-flight mass spectrometry. Samples were measured in data-dependent auto tandem mass spectrometry mode and identified by fragment spectra comparison, retention time and accurate mass. Approximately 500 NPS, including 195 synthetic cannabino…
Occurrence of glyphosate in beer from the Latvian market.
2018
A sensitive LC-MS/MS method for the determination of glyphosate in beer has been developed, validated, and applied to analyse 100 beer samples from 24 different producers and distributors in Latvia. The selected samples represented most beer brands and varieties sold in local supermarkets. Different procedures for sample preparation and chromatographic separation were compared. The final version of the method consisted of solid phase extraction, chromatographic separation on aminopropyl stationary phase, and detection using tandem mass spectrometry. The concentration of glyphosate in beer varied from below the LOD of 0.2 μg kg-1 up to 150 μg kg-1, higher than previously reported. Significan…
Factors influencing adjustment to remote work: Employees’ initial responses to the covid-19 pandemic
2021
The COVID-19 crisis has disrupted when, where, and how employees work. Drawing on a sample of 5452 Finnish employees, this study explores the factors associated with employees’ abrupt adjustment to remote work. Specifically, this study examines structural factors (i.e., work independence and the clarity of job criteria), relational factors (i.e., interpersonal trust and social isolation), contextual factors of work (i.e., change in work location and perceived disruption), and communication dynamics (i.e., organizational communication quality and communication technology use (CTU)) as mechanisms underlying adjustment to remote work. The findings demonstrate that structural and contextual fac…
Characterisation of disaccharide fragments from the enzymatic digestion of heparin by liquid secondary ion mass spectrometry
1988
Disaccharide fragments resulting from the enzymatic digestion of heparins with heparinase have been purified by gel filtration chromatography and directly analyzed by positive and negative ion liquid secondary ion mass spectrometry (LSIMS). Following the chromatographic purification from excess sodium salt, the mass spectra of di- and tetrasaccharide fragment mixtures enabled the identification of up to three covalently bound sulfate moieties per glycosaminoglycan-disaccharide unit, by means of their molecular ions, containing the corresponding alkali-counterions.
Molecular approach for the characterization of ancient /degraded Cyperus sp.specimens
2013
The aim of this work has been to apply and improve the efficiency of molecular tools for the identification of Cyperus sp. from difTerent sources. Total DNA was extracted from fresh, degraded and ancient specimens. DNA molecules were the template for in vitro amplification of specific target regions referred to rcbL plastid gene (ribulose-l,5 -biphosphate carboxylase/oxygenase large subunit). Dedicated DNA extraction and amplification protocols have been applied specifically for fresh/degraded and ancient samples. Particularly, specific set of primer, annealing temperatures and reaction mixtures have been performed. The PCR products, single DNA fragments, were resolved on agarose gel electr…
Testing for goodness rather than lack of fit of an X–chromosomal SNP to the Hardy-Weinberg model
2019
The problem of checking the genotype distribution obtained for some diallelic marker for compatibility with the Hardy-Weinberg equilibrium (HWE) condition arises also for loci on the X chromosome. The possible genotypes depend on the sex of the individual in this case: for females, the genotype distribution is trinomial, as in the case of an autosomal locus, whereas a binomial proportion is observed for males. Like in genetic association studies with autosomal SNPs, interest is typically in establishing approximate compatibility of the observed genotype frequencies with HWE. This requires to replace traditional methods tailored for detecting lack of fit to the model with an equivalence test…
Propiedades psicométricas del Inventario Breve de Síntomas-18 en una muestra heterogénea de pacientes de cáncer adulto
2019
espanolResumen El Inventario Breve de Sintomas-18 (BSI-18) es un instrumento de cribado ampliamente utilizado para evaluar distres emocional (GSI) y tres tipos de sintomas: ansiedad, depresion, y somatizacion. Este trabajo estudia la estructura factorial del BSI-18, utilizando analisis factorial confirmatorio (AFC), su fiabilidad y validez convergente, asi como su invarianza factorial a traves del sexo. Una muestra de 1183 pacientes de cancer completo el BSI 18 y la lista de problemas de la NCCN. Los modelos jerarquicos de tres y cuatro factores proporcionaron ajustes adecuados y similares. Sin embargo, el modelo de tres factores (propuesta teorica) fue seleccionado por razones metodologica…
Measuring dissatisfaction with coauthorship: An empirical approach based on the researchers’ perception
2019
Abstract Increasing levels of collaboration constitute one of the characteristics of science. However, the knowledge production system is based on a fundamental discordance: on the one hand, it is cooperative in nature, with links articulated through coauthorships, and on the other, the systems for assigning merit and distributing rewards function on an individual scale. This contradiction can give rise to dysfunction and inappropriate practices. This study analyses researchers’ perceptions about the problems associated with authorship in scientific publications. We make use of a coauthorship dissatisfaction index that measures the degree of dissatisfaction with the author order on the byli…
Hairy black-holes in shift-symmetric theories
2020
Scalar hair of black holes in theories with a shift symmetry are constrained by the no-hair theorem of Hui and Nicolis, assuming spherical symmetry, time-independence of the scalar field and asymptotic flatness. The most studied counterexample is a linear coupling of the scalar with the Gauss-Bonnet invariant. However, in this case the norm of the shift-symmetry current $J^2$ diverges at the horizon casting doubts on whether the solution is physically sound. We show that this is not an issue since $J^2$ is not a scalar quantity, since $J^\mu$ is not a diff-invariant current in the presence of Gauss-Bonnet. The same theory can be written in Horndeski form with a non-analytic function $G_5 \s…
Current trends on the determination of organic UV filters in environmental water samples based on microextraction techniques – A review
2018
UV filters are a group of cosmetic ingredients commonly used in a wide variety of cosmetic products to protect users from UV solar radiation. They belong to different chemical families, such as benzophenones, p-aminobenzoates, salicylates, cinnamates, benzotriazoles, benzimidazoles, camphor derivatives, triazines, etc. These cosmetic ingredients are considered as emerging contaminants since they easily reach the aquatic environment, where they are accumulated causing harmful effects in the flora and fauna despite being present at the ng L-1 level. Therefore, the development of sensitive and selective analytical methods for their environmental surveillance monitoring is of high interest. In …