Search results for "Quantitative"
showing 10 items of 2409 documents
Tetra- and pentachlorodibenzothiophenes are formed in waste combustion
1991
Abstract Two different waste combustion samples have been analyzed for tetra- and pentachlorodibenzothiophenes. HRGC/HRMS with a resolution of 20 000 was used for identification. By resolution of 10 000 chlorinated dibenzo-p-dioxins and some unknown compounds gave GC/SIM peaks at the exact masses of the chlorinated dibenzothiophenes. These peaks were no more present by resolution 20 000. Several tetra- and pentachlorodibenzothiophenes were found in both samples. In the other one of the samples the concentrations were seemingly high although exact quantitative determination could not be done.
Influence of volatile solids and pH for the production of volatile fatty acids: batch fermentation tests using sewage sludge
2021
The aim of this work was to study the effect of volatile suspended solid (VSS) and pH on volatile fatty acids (VFA) production from waste activated sludge (WAS) fermentation by means of batch tests. The final goal was to gain insights to enhance VFA stream quality, with the novelty of using WAS with high sludge retention time. Results revealed that the optimum conditions to maximize VFAs and minimize nutrients and non-VFA sCOD are a VSS concentration of 5.9 g/L and initial pH adjustment to pH 10. The WAS bacterial community structures were analysed according to Next Generation Sequencing (NGS) of 16S rDNA amplicons. The results revealed changes of bacterial phyla abundance in comparison wit…
Chromatographic retention–activity relationships for prediction of the toxicity pH-dependence of phenols
2007
Abstract An investigation of the use of the chromatographic retention (log k ) as an in vitro approach for modeling the pH-dependence of the toxicity to Guppy of phenols is developed. A data set of 19 phenols with available experimental toxicity–pH data was used. The importance of the mechanism of toxic action (MOA) of phenols was studied. log k data at three pH values were used for the phenols classification and two groups or ‘MODEs’ were identified. For one ‘MODE’ a quantitative retention–activity relationship (QRAR) model was calculated. Finally, the model was used to assess the toxicity to Guppy of phenols at different pH values. The results of this investigation suggest that chromato…
Vides apstākļu ietekme uz mikro- un makroelementu saturu pārtikas produktos Latvijā
2014
Bez vitāli svarīgo mikro- un makroelementu ieneses pārtikā no vides (augsnes, ūdens un gaisa) ir iespējams arī barības ķēdes, t. sk., pārtikas piesārņojums ar toksiskiem vai potenciāli toksiskiem elementiem, piemēram, As, Cd, Hg, Pb. Promocijas darba mērķa ietvaros tika veikta Latvijā iegūtu pārtikas produktu paraugu mikro- un makroelementu sastāva kvantitatīvā analīze, lai noskaidrotu vides apstākļu ietekmi uz elementu koncentrāciju un ieneses ceļiem pārtikā. Papildus, lai vērtētu elementu biopieejamību barības ķēdē, tika veikta eksperimentāla pārtikas kultūraugu audzēšana mākslīgi piesārņotā augsnē. Iegūtie dati liecina par vairāku dabiskas un antropogēnas izcelsmes vides apstākļu, piemēr…
Does Culture Matter? : Measuring Cross-Country Perceptions of CSR Communication Campaigns about COVID-19
2022
The COVID-19 pandemic has brought several challenges to businesses and societies. In response, many corporations have supported local communities and authorities in the management of the pandemic. Although these initiatives, which can be considered forms of corporate social responsibility (CSR), were highly coupled with explicit CSR communication campaigns, little is known about whether these campaigns were effective. Previous research indicates that culture can shape people’s perceptions of CSR initiatives and communications, suggesting that businesses pay attention to careful consideration of cultural norms for effective CSR communication. However, the COVID-19 pandemic as a new CSR setti…
Thermodynamics of Rubber Elasticity
2001
A thermodynamic study of an isotropic rubber band under uniaxial stress is presented on the basis of its equation of state. The behavior of the rubber band is compared with both that of an ideal elastomer and that of an ideal gas, considering the generalized Joule's law as the ideality criterion.
Probabilistic stability analysis of social obesity epidemic by a delayed stochastic model
2014
Abstract Sufficient conditions for stability in probability of the equilibrium point of a social obesity epidemic model with distributed delay and stochastic perturbations are obtained. The obesity epidemic model is demonstrated on the example of the Region of Valencia, Spain. The considered nonlinear system is linearized in the neighborhood of the positive point of equilibrium and a sufficient condition for asymptotic mean square stability of the zero solution of the constructed linear system is obtained.
Equilibrium swelling properties of polyampholytic hydrogels
1996
The role of counter ions and ion dissociation in establishing the equilibrium swelling of balanced and unbalanced polyampholytic hydrogels has been investigated experimentally and theoretically. The swelling dependence on both the net charge offset and the external bath salt concentration has been examined using an acrylamide based polyampholytic hydrogels. By careful consideration of the swelling kinetics, we illustrate the effects of ion dissociation equilibria and counter ion shielding in polyampholytic hydrogels near their balance point where both polyelectrolyte and polyampholyte effects are present. The theory considers a Flory type swelling model where the Coulombic interactions betw…
Two Half-Truths Make a Whole? On Bias in Self-Reports and Tracking Data
2019
The pervasive use of mobile information technologies brings new patterns of media usage, but also challenges to the measurement of media exposure. Researchers wishing to, for example, understand the nature of selective exposure on algorithmically driven platforms need to precisely attribute individuals’ exposure to specific content. Prior research has used tracking data to show that survey-based self-reports of media exposure are critically unreliable. So far, however, little effort has been invested into assessing the specific biases of tracking methods themselves. Using data from a multimethod study, we show that tracking data from mobile devices is linked to systematic distortions in sel…
Comparison of Causality Network Estimation in the Sensor and Source Space: Simulation and Application on EEG
2021
The usage of methods for the estimation of the true underlying connectivity among the observed variables of a system is increasing, especially in the domain of neuroscience. Granger causality and similar concepts are employed for the estimation of the brain network from electroencephalogram (EEG) data. Also source localization techniques, such as the standardized low resolution electromagnetic tomography (sLORETA), are widely used for obtaining more reliable data in the source space. In this work, connectivity structures are estimated in the sensor and in the source space making use of the sLORETA transformation for simulated and for EEG data with episodes of spontaneous epileptiform discha…