Oxidative dehydrogenation of ethane on Pt–Sn impregnated monoliths

The oxidative dehydrogenation of ethane was studied over Pt–Sn impregnated monoliths at 1 bar, 600–900 °C and with different contents of oxygen, hydrogen and steam in the feed gas. As expected a decrease in oxygen in the feed led to a decrease in the conversion of ethane due to lower temperatures in the reactor. Adding steam to the feed showed no effect on the ethane conversion or the ethene selectivity. When the hydrogen/ethane ratio in the feed was varied from 0 to 0.5 at 700 and 850 °C, it resulted in a significant increase in the selectivity to ethene while the ethane conversion remained relatively unchanged. At 700 °C the selectivity increased from about 50% to 93% (carbon basis) with only a small decrease in the conversion of ethane. The results clearly show that both Pt and Sn have a catalytic effect. Pt caused the ethane conversion to rise and addition of Sn resulted in much better ethene selectivity. However, even though Sn alone showed some catalytic effect at lower temperatures, it cannot explain the great difference between the Pt and Pt–Sn catalysts. A reasonable assumption is therefore that there exist interactions between Pt and Sn that gives the Pt–Sn catalysts excellent properties for oxidative dehydrogenation of ethane, in particular upon addition of hydrogen.     

Effect of freezing temperature on the color of frozen salmon

New freezing methods developed with the purpose of improved product quality after thawing can sometimes be difficult to get accepted in the market. The reason for this is the formation of ice crystals that can give the product a temporary color loss and make it less appealing. We have here used microscopy to study ice crystal size as a function of freezing temperature by investigating the voids in the cell tissue left by the ice crystals. We have also investigated how freezing temperature affects the color and the visible absorption spectra of frozen salmon. Freezing temperatures previously determined to be the best for quality after thawing (-40 to -60 °C) were found to cause a substantial loss in perceived color intensity during frozen state. This illustrated the conflict between optimal freezing temperatures with respect to quality after thawing against visual appearance during frozen state. Low freezing temperatures gave many small ice crystals, increased light scattering and an increased absorption level for all wavelengths in the visible region. Increased astaxanthin concentration on the other hand would give higher absorption at 490 nm. The results showed a clear potential of using visible interactance spectroscopy to differentiate between poor product coloration due to lack of pigmentation and temporary color loss due to light scattering by ice crystal. This type of measurements could be a useful tool in the development of new freezing methods and to monitor ice crystal growth during frozen storage. It could also potentially be used by the industry to prove good product quality. PRACTICAL APPLICATION: In this article we have shown that freezing food products at intermediate to low temperatures (-40 to -80 °C) can result in paler color during frozen state, which could affect consumer acceptance. We have also presented a spectroscopic method that can separate between poor product color and temporary color loss due to freezing.     

Predictors of digital competence in 7th grade: a multilevel analysis

Since 2006, the ability to use information and communication technology (ICT) has been included as a key competence in the curriculum in Norway, and specific competence aims are developed for most grades. The aim of this study was to identify students' ability to use ICT according to the competence aims, and to examine factors that can predict students' digital competence. A sample of 1793 students and 125 school leaders from 125 schools was used. The findings show variation in digital competence both between students and between schools. Results from a multilevel analysis showed that higher levels of mastery orientation and self‐efficacy (i.e., motivation) and the students' family background (i.e., language integration and the number of books at home) were predictors of students' levels of digital competence. Additionally, when school leaders reported higher levels of culture for professional development among the teachers at school, increased levels of digital competence were found among students. Challenges for schools and teachers to support students' motivation and to emphasize digital inclusion still prevail.     

Supporting Conceptual Awareness with Pedagogical Agents

This paper describes a series of efforts in building and conceptualizing software agents for distributed collaborative learning. The agents are referred to as pedagogical agents. We have integrated pedagogical agents within two collaborative environments, TeamWave Workplace and Future Learning Environment. The role of agents in these environments differs from past work on software agents in their function as extended awareness mechanisms, focusing on task and concept awareness (conceptual awareness). Our approach is stimulated by Meads theory of the Generalized Other. The agents collect statistical information on user activity and analyze the information based on principles of collaboration and knowledge building (participation, group interaction, and scientific discourse). Furthermore, the agents define a trajectory in a pedagogical agent design space, which we define in terms of four dimensions: presentation, intervention, task, and pedagogy. We end the paper by comparing our approach with related work.This revised version was published online in March 2005 with corrections to the cover dateThe CoPAS study presented in this article was performed while the author was a graduate student at the Department of information science, University of Bergen, Norway     

Are school meals a viable and sustainable tool to improve the healthiness and sustainability of children´s diet and food consumption? A cross-national comparative perspective

There is little agreement among governments, institutions, scientists and food activists as to how to best tackle the challenging issues of health and sustainability in the food sector. This essay discusses the potential of school meals as a platform to promote healthy and sustainable food behavior. School meal programs are of particular interest for improving public diet because they reach children at a population scale across socio-economic classes and for over a decade of their lives, and because food habits of children are more malleable than those of adults. Current research on the history and health implications of school meal programs is reviewed in a cross-national comparative framework, and arguments explored that speak for the need of a new developmental phase of school meals as an integrative learning platform for healthy and sustainable food behavior. Nutritional, social, practical, educational, economical, political, and cultural perspectives and challenges linked to the implementation of healthy and sustainable school meals are discussed. Finally, the need for long-term interventions and evaluations is highlighted and new research directions are proposed.     

Low salt brining of pre-rigor filleted farmed cod (Gadus morhua L.) and the effects on different quality parameters

Pre-rigor processing of cod fillets may have economic benefits, but this potential has usually been overshadowed by process-linked difficulties such as pin bone removal, rapid rigor onset and higher drip losses. The aim of this work was to study the impact on fillet quality parameters after immersing pre-rigor filleted farmed cod in different NaCl solutions ranging from 15 to 60 g/L. Temperature of the fish at death was 4 °C, in immersion solutions 2 °C, and following immersion the fillets were stored in ice within plastic bags for 14 days. As controls, one group was filleted pre-rigor but not immersed, and one group was filleted post-rigor and not immersed. Immersing in salt solution resulted in better yield compared to both control groups. Higher salt content generally increased rigor contraction, but significantly reduced fillet gaping and the force required to pull pin bones. Thus, relatively low salt levels within the fillets had a positive impact on some of the problems associated with pre-rigor filleting.     

Association between novel indices of malnutrition-inflammation complex syndrome and cardiovascular disease in hemodialysis patients

Background: Inflammation and malnutrition are recognized as important risk factors for cardiovascular disease (CVD) in hemodialysis (HD) patients. Owing to substantial short‐term variability of serum C‐reactive protein (CRP), more reliable markers of malnutrition–inflammation complex syndrome should be sought with stronger associations with the risk of CVD in HD patients. We therefore explored the clinical relevance of a composite inflammatory index (prognostic inflammatory and nutritional index [PINI]) and of muscle protein mass indicators, derived from creatinine kinetics. Methods: This cross‐sectional study included 177 HD patients (89 women and 88 men; median age, 67.73 years). CVD and risk factors were assessed using medical charts, clinical examination, and biochemical measurements performed at inclusion. Lean body mass (LBM) was derived from creatinine kinetic modeling, whereas PINI was calculated as the ratio (CRP ×α1‐acid‐glycoprotein)/(albumin × transthyretin). Patients were divided according to the presence or absence of established CVD. Results: The traditional risk factors diabetes (odds ratio [OR], 5.83; p = 0.0045) and smoking (OR, 3.50; p < 0.02) were associated with an increase in prevalent CVD. Low transthyretin (OR, 3.79; p < 0.02) and high levels of CRP (OR, 2.70; p < 0.05), PINI (OR, 3.44; p < 0.02), observed LBM (OR, 3.01; p < 0.05), and the ratio of observed/expected LBM (OR, 4.24; p < 0.01) were associated with CVD after adjustment for age, sex, dialysis center, and dialysis vintage. After additional adjustment for diabetes and smoking, only PINI (OR, 2.85; p = 0.0446) and observed/expected LBM (OR, 2.96; p = 0.0361) were still significant. Conclusion: PINI and LBM are associated with increased relative risk for having CVD and could be used routinely to examine the degree of severity of malnutrition inflammation complex syndrome.     

Innovative pedagogical practice with ICT in three Nordic countries – differences and similarities

Three Nordic countries, Denmark, Finland and Norway, participated in the IEA SITES 2006 study. All the three countries have launched huge policy and investment programmes to promote digital literacy and readiness for the information age. In relation to the remarkable Finnish Programme for International Student Assessment (PISA) results, it is interesting to see if the Finnish school system may be better suited to ground and contextualize pedagogical practice with Information and Communication Technologies (ICT) than the Danish and Norwegian counterparts. One main difference is that the Finnish system seems to anchor decisions about and interpretations on how ICT should be utilized stronger at the local level than the two other systems. One of the general goals in the policy programmes is to get teachers to innovate with ICT in the classrooms. The Second Information Technology in Education Study (SITES) 2006 indicators for two innovative pedagogical orientations, lifelong learning orientation and connectedness are utilized to compare teachers from the three nations. The main findings is that Finnish teachers are either not differing or they are scoring significantly lower on the two indicators than teachers from Denmark or Norway. The exception is Finnish science teachers who are more inclined towards using ICT in lifelong learning practices than their Danish and Norwegian counterparts. Generally, the Finnish teachers seem to be more autonomous in their pedagogical choices but may also be more conservative than the Danish and Norwegian teachers in making use of ICT.     

Chemical looping combustion in a rotating bed reactor--finding optimal process conditions for prototype reactor

A lab-scale rotating bed reactor for chemical looping combustion has been designed, constructed, and tested using a CuO/Al(2)O(3) oxygen carrier and methane as fuel. Process parameters such as bed rotating frequency, gas flows, and reactor temperature have been varied to find optimal performance of the prototype reactor. Around 90% CH(4) conversion and >90% CO(2) capture efficiency based on converted methane have been obtained. Stable operation has been accomplished over several hours, and also--stable operation can be regained after intentionally running into unstable conditions. Relatively high gas velocities are used to avoid fully reduced oxygen carrier in part of the bed. Potential CO(2) purity obtained is in the range 30 to 65%--mostly due to air slippage from the air sector--which seems to be the major drawback of the prototype reactor design. Considering the prototype nature of the first version of the rotating reactor setup, it is believed that significant improvements can be made to further avoid gas mixing in future modified and up-scaled reactor versions.