An ARXPS and ERXPS study of quaternary ammonium and phosphonium ionic liquids: utilising a high energy Ag Lα’ X-ray source

Introduction Ionic liquid (IL) surface science has experienced rapid expansion in recent years. As such, a multitude of ultra-high vacuum (UHV) techniques have been used to probe the IL/vacuum interface including laboratory and synchrotron X-ray photoelectron spectroscopy (XPS), metastable impact electron spectroscopy (MIES), low energy ion scattering (LEIS), Rutherford backscattering (RBS) and neutral impact collision ion scattering spectroscopy (NICISS). To date, the vast majority of these studies have focused upon cyclic nitrogen-containing cations, particularly the 1-alkyl-3-methylimidazolium family, whereas acyclic cations including tetraalkylammonium and –phosphonium have been overlooked despite their potential use in a wide range of existing applications including heterogeneous catalysis, gas capture/separation, and nanoparticle formation

Thermolysis of Organofluoroborate Ionic Liquids to NHC-Organofluoroborates

A range of dialkylimidazolium organotrifluoroborate ionic liquids were prepared by anion metathesis from newly available potassium organotrifluoroborate salts, and their physical properties were characterized by TGA, DSC, and STA. Thermal decomposition was subsequently investigated under vacuum with direct insertion mass spectrometry to determine whether thermolysis was a viable route to prepare N-heterocyclic carbene organofluoroborates, which are an important class of emerging compounds. Several key targets were identified, which highlighted the potential to shortcut complex synthetic methodologies otherwise required to access such molecules

Continuous-Flow Alkene Metathesis: The Model Reaction of 1-Octene Catalyzed by Re2O7/alfa-Al2O3 with Supercritical CO2 as a Carrier

In the presence of Re2O7 supported on γ-Al2O3, the self-metathesis of 1-octene was conveniently carried out under continuous-flow (CF) conditions using supercritical CO2 (scCO2) as a carrier. This investigation allowed optimization of reaction parameters, the best values of which were found to be 100 °C and 90 bar, operating at flow rates of 0.05 and 1 mL min−1 for 1-octene and scCO2, respectively, the reaction proceeded with very good self-metathesis selectivity (>90%) and an average productivity of ∼0.24 mL tetradecene gRe −1 min−1 . Although the catalyst was completely deactivated after the first 100–150 min of reaction, it could be recycled for (at least) five subsequent reactions without any loss of performance. The results provided incontrovertible evidence that for the investigated reaction, scCO2was a superior carrier with respect to conventional liquids, such as toluene or n-hexane

Halometallate ionic liquids: thermal properties, decomposition pathways, and life cycle considerations

Halometallate ionic liquids provide new opportunities for industrial catalytic processes because of their unique blend of physical and chemical properties. Tunability underpins the success of ionic liquids because small structural changes can have drastic effects on either property. Catalysis can be optimised by adjusting structures to target properties such as Lewis basicity and acidity, but the structural changes have simultaneous impacts on physical properties. In this work, we provide a thorough, methodical, and reliable list of thermal parameters to help define temperature limits to prevent catalyst poisoning and limit the need to replace costly and environmentally demanding solvents. Mechanistic insights show that decomposition is particularly detrimental for halometallate ionic liquids, and life cycle analysis highlights that lower levels of organic cations are better for economic and environmental sustainability

Mind your step: the effects of mobile phone use on gaze behavior in stair climbing

Stair walking is a hazardous activity and a common cause of fatal and non-fatal falls. Previous studies have assessed the role of eye movements in stair walking by asking people to repeatedly go up and down stairs in quiet and controlled conditions, while the role of peripheral vision was examined by giving participants specific fixation instructions or working memory tasks. We here extend this research to stair walking in a natural environment with other people present on the stairs and a now common secondary task: Using one's mobile phone. Results show that using the mobile phone strongly draws one's attention away from the stairs, but that the distribution of gaze locations away from the phone is little influenced by using one's phone. Phone use also increased the time needed to walk the stairs, but handrail use remained low. These results indicate that limited foveal vision suffices for adequate stair walking in normal environments, but that mobile phone use has a strong influence on attention, which may pose problems when unexpected obstacles are encountered

Validity and Reliability of the Strengths and Difficulties Questionnaire in 5–6 Year Olds: Differences by Gender or by Parental Education?

Introduction: The Strengths and Difficulties Questionnaire (SDQ) is a relatively short instrument developed to detect psychosocial problems in children aged 3-16 years. It addresses four dimensions: emotional problems, conduct problems, hyperactivity/inattention problems, peer problems that count up to the total difficulties score, and a fifth dimension; prosocial behaviour. The validity and reliability of the SDQ has not been fully investigated in younger age groups. Therefore, this study assesses the validity and reliability of the parent and teacher versions of the SDQ in children aged 5-6 years in the total sample, and in subgroups according to child gender and parental education level. Methods: The SDQ was administered as part of the Dutch regularly provided preventive health check for children aged 5-6 years. Parents provided information on 4750 children and teachers on 4516 children. Results: Factor analyses of the parent and teacher SDQ confirmed that the original five scales were present (parent RMSEA = 0.05; teacher RMSEA = 0.07). Interrater correlations between parents and teachers were small (ICCs of 0.21-0.44) but comparable to what is generally found for psychosocial problem assessments in children. These correlations were larger for males than for females. Cronbach's alphas for the total difficulties score were 0.77 for the parent SDQ and 0.81 for the teacher SDQ. Four of the subscales on the parent SDQ and two of the subscales on the teacher SDQ had an alpha <0.70. Alphas were generally higher for male children and for low parental education level. Discussion: The validity and reliability of the total difficulties score of the parent and teacher SDQ are satisfactory in all groups by informant, child gender, and parental education level. Our results support the use of the SDQ in younger age groups. However, some subscales are less reliable and we recommend only to use the total difficulties score for screening purposes

Factores que determinan la acción de chatear por celular mientras se camina

1 recurso en línea (97 páginas) : ilustraciones, figuras, tablas.El presente trabajo de investigación estudia los factores que determinan la acción de chatear mientras se camina, con el propósito de analizar sus causas, desde la perspectiva de los usuarios, y plantear medidas que ayuden a mitigar la conducta de chatear mientras se camina de los peatones. La metodología usada tuvo dos perspectivas basadas en la aplicación de una encuesta a una muestra representativa de la población. En primer lugar, se hizo un análisis empírico a partir de la obtención de barras apiladas divergentes, para un conjunto de indicadores de variables latentes, basados en indicadores de tipo Likert. En segundo lugar, tomando los datos de un experimento de preferencias declaradas, mediante un proceso iterativo, se hizo la estimación de modelos de tipo Logit multinomial a través del software de uso libre Biogeme. De esta manera se pudo concluir que los factores determinantes de la conducta de chatear mientras se caminan están relacionados con características sociales del individuo, políticas de tránsito, características de la infraestructura urbana, características socio-económicas de las personas, así como las características propias del uso del teléfono de cada individuo.Bibliografía y webgrafía: páginas 94-97.PregradoIngeniero de Transport