An infrared investigation of the catalyst formation in the system Ni(acac)2, C3H4, (iBu)3AL for propadiene polymerization

The catalyst formation in the system Ni(acac)2, C3H4, (iBu)3Al was investigated by means of infrared spectroscopy. It was found that the Al(acac)3 and (iBu)2Al(acac) formed are both by-products of catalyst formation without a catalytic activity. Ni(acac)2 loses its acac groups forming the unstable (iBu)2Ni compound; without C3H4 being present, this compound disproportionates to Ni metal and isobutane and isobutene. In the presence of C3H4 an allyl-nickel complex is formed, which reacts with (iBu)3Al to give the actual catalyst, possibly a bimetallic allyl—nickel-aluminium complex. Catalysts such as Ni(acac)2, C3H4, (iBu)3Al and (πC3H5)2Ni with or without (iBu)3Al all selectively give 1, 2, 1, 2-polypropadiene. A Lewis base like pyridine not only decreases the polymerization rate but also changes the selectivity towards the formation of 1, 2, 2, 1-polymer

Effectiveness of interventions using self-monitoring to reduce sedentary behavior in adults : a systematic review and meta-analysis

Background: Sedentary behavior occurs largely subconsciously, and thus specific behavior change techniques are needed to increase conscious awareness of sedentary behavior. Chief amongst these behavior change techniques is self-monitoring of sedentary behavior. The aim of this systematic review and meta-analysis was to evaluate the short-term effectiveness of existing interventions using self-monitoring to reduce sedentary behavior in adults. Methods: Four electronic databases (PubMed, Embase, Web of Science, and The Cochrane Library) and grey literature (Google Scholar and the International Clinical Trials Registry Platform) were searched to identify appropriate intervention studies. Only (cluster-)randomized controlled trials that 1) assessed the short-term effectiveness of an intervention aimed at the reduction of sedentary behavior, 2) used self-monitoring as a behavior change technique, and 3) were conducted in a sample of adults with an average age >= 18 years, were eligible for inclusion. Relevant data were extracted, and Hedge's g was used as the measure of effect sizes. Random effects models were performed to conduct the meta-analysis. Results: Nineteen intervention studies with a total of 2800 participants met the inclusion criteria. Results of the meta-analyses showed that interventions using self-monitoring significantly reduced total sedentary time (Hedges g = 0,32; 95% CI = 0,14 - 0,50; p = 0,001) and occupational sedentary time (Hedge's g = 0,56; 95% CI = 0,07 - 0,90; p = 0,02) on the short term. Subgroup analyses showed that significant intervention effects were only found if objective self-monitoring tools were used (g = 0,40; 95% CI = 0,19 - 0,60; p < 0,001), and if the intervention only targeted sedentary behavior (g = 0,45; 95% CI = 0,15-0,75; p = 0,004). No significant intervention effects were found on the number of breaks in sedentary behavior. Conclusions: Despite the small sample sizes, and the large heterogeneity, results of the current meta-analysis suggested that interventions using self-monitoring as a behavior change technique have the potential to reduce sedentary behavior in adults. If future - preferably large-scale studies - can prove that the reductions in sedentary behavior are attributable to self-monitoring and can confirm the sustainability of this behavior change, multi-level interventions including self-monitoring may impact public health by reducing sedentary behavior

Non-radioactive in situ hybridization for the detection of cytomegalovirus infections

Contains fulltext : 4468.pdf (publisher's version ) (Open Access

Trends in Australian children traveling to school 1971–2003: Burning petrol or carbohydrates?

Objective. To determine how Australian children traveled to and from school between 1971 and 2003. Methods. The 1971 (n=4284), 1981 (n=4936), 1991 (n=662) and 1999–2003 (n=816) Household Travel Surveys from the New South Wales Government Department of Planning were used to determine the mode of transport kids (5–14 years) took to and from school in the area of Sydney (Australia). Results. The results showed that the percentage of children aged 5–9 that walked to school was 57.7, 44.5, 35.3 and 25.5 in 1971, 1981, 1991 and 1999–2003, respectively. The percentage of children aged 5–9 that were driven to school by car in the four surveys was 22.8, 37.3, 53.9 and 66.6, respectively. The results for children aged 10–14 were similar, walking decreased from 44.2% to 21.1% and car use increased from 12.2% to 47.8% over the study period. Similar results were found for travel from school and there were no major differences between boys and girls. Conclusion. Between 1971 and 2003, Australian children's mode of travel to and from school has markedly shifted from active (walking) to inactive (car) modes

The evolution of time use approaches for understanding activities of daily living in a public health context

This Supplement aims to raise awareness and knowledge of how time use surveys may be applied to studying health behaviours such as physical activity, sedentary behaviour, and eating. This commentary provides an overview and discussion of the papers in this Supplement about time use and health research, and considers possible future directions for the field

Simultaneous Spectrophotometric Calibration of Wavelength and Absorbance in an Interlaboratory Survey Using Holmium Oxide (HO2O3) in Perchloric Acid as Reference, Compared with p-Nitrophenol and Cobaltous Sulphate Solutions (1978-1984)

Peer Reviewe

Educational differences in the validity of self-reported physical activity

BACKGROUND: The assessment of physical activity for surveillance or population based studies is usually done with self-report questionnaires. However, bias in self-reported physical activity may be greater in lower educated than in higher educated populations. The aim of the present study is to describe educational differences in the validity of self-reported physical activity. METHODS: We included 196 healthy adults (age 57 ± 15.4, of whom 17 % low, 24 % medium and 59 % high educated). Criterion validity of an adapted International Physical Activity Questionnaire was assessed against the ActiGraph GT3X+ accelerometer. RESULTS: While criterion validity of self-reported physical activity was low to moderate in the total sample (Spearman rho ranged from 0.16 to 0.27, depending on the variables used), the validity in lower educated respondents was poor (-0.07 to 0.05). CONCLUSIONS: The results confirm the hypothesis that self-report physical activity questionnaires are less valid in lower educated populations