Reaction engineering studies in a polytropic fixed-bed reactor over a highly active and selective catalyst for oxidative methane coupling

The oxidative coupling of methane (OCM) was carried out in a polytropic fixed-bed reactor applying a Zr/La/Sr catalyst developed by the Neste company. Over this catalyst the OCM reaction follows a complex reaction scheme which includes primary parallel reaction steps to CO, CO₂ and C₂H₆ and consecutive reactions of ethane to ethylene or CO_x. Yield of higher hydrocarbons C₂₊ obtained with this catalyst strongly depended on reaction conditions, i.e. low partial pressures of methane and oxygen obtained by diluting the feed gas with nitrogen and high reaction temperatures promoted C₂₊ selectivity and yield. The maximum yield amounted to 21.4% (20 Vol.-% CH₄, 9 Vol.-% O₂, 71 Vol.-% N₂, T = 860°C; X_CH4 = 41.8%, S = 52.5%). This result belongs to the highest yields reported in the open literature.     

EOC: Electronic Building Blocks for Embedded Systems

The embedded-object concept, EOC, applies common object-oriented software methods to Lego-like hardware-software entities. These modular entities, representing objects in object-oriented design, function as electronic building blocks that can be assembled into new embedded systems. The goal of the EOC is to make embedded-system design faster and easier while preserving the commercial applicability of the resulting devices.     

Ozone effects on Sphagnum mosses,carbon dioxide exchange and methane emission in boreal peatland microcosms

Microcosms of a boreal peatland originating from an oligotrophic fen in Eastern Finland were fumigated under four ozone concentrations (0, 50, 100 and 150 ppb O3) in laboratory growth chambers during two separate experiments (autumn and summer) for 4 and 6 weeks, respectively. Ozone effects on Sphagnum mosses and the fluxes of carbon dioxide and methane were evaluated. In both experiments, the three Sphagnum species studied showed only a few significant responses to ozone. In the autumn experiment, membrane permeability of S. angustifolium, measured as conductivity and magnesium leakage, was significantly higher under ozone fumigation (P = 0.005 and < 0.001, respectively), and there was a distinct dose-dependence. S. magellanicum showed no clear responses, either for membrane leakage or pigment content. There were no substantial ozone responses in the gross photosynthesis or net CO2 exchange during the 6-week-long summer experiment, but dark ecosystem respiration was transiently increased by ozone concentration of 100 ppb after 14 days of exposure (P < 0.05). Fumigation with 100 ppb of ozone, however, more than doubled (P < 0.05) methane emission from the peatland monoliths. Our results suggest that increasing tropospheric ozone concentration may cause substantial changes in the carbon gas cycling of boreal peatlands, even though these changes are not closely associated with the changes in Sphagnum vegetation.     

Accessing Context in Wearable Computers

We present an easy interaction technique for accessing location-based contextual data shown on a head-worn wearable computer display. Our technique, called Context Compass, is based on a regular compass metaphor. Each object belonging to the user’s current context is visualised on a linear compass shown on the screen. The object directly in front of the user is shown in the middle of the compass and can be activated. Whenever the user turns his or her head, the objects on the screen move accordingly. Therefore, an object can be selected by simply turning one’s head towards it. Context Compass consumes a minimal amount of screen space, making it ideal for usage with see-through head-worn displays. An initial pilot study, applying a newly developed usability method customised especially for Context Compass, revealed that Context Compass can be learned virtually immediately. Further, the method itself proved to be successful in evaluating techniques such as Context Compass.     

Cardiac status and cardiovascular risk factors among Finnish sea pilots

The present study investigated the expressed number of CR1 on erythrocytes (E) in relationship of the CR1 density genotype from 46 patients with systemic lupus erythematosus (SLE) and 47 healthy volunteers. The CR1 genotype was determined by a method based on polymerase chain reaction (PCR) amplification of the genomic DNA fragment of 1.8 kb separated by HindIII endonuclease digestion and agarose gel electrophoresis. Our data supported the earlier results that the number of binding sites/E for monoclonal anti-CR1 decreased among SLE patients compared with normal individuals having the same alleles for the CR1/E density. At the same time the novelty of our recent results was that the decreased expression of CR1 on E correlated significantly with kidney involvement in patients homozygous for the CR1/E high density allele (HH). These data suggest that the deficiency of the detectable number of CR1 on erythrocytes is acquired in this SLE population.     

Time-out in user interface: the case of mobile text input

In many user interfaces with restricted input capabilities, a time-out is used to automatically change the user interface (UI) from one mode to another. In this paper, we study the learning of time-outs and the effect of feedback on it in the case of mobile phone text entry. The effects of three different feedback schemes (auditory/visual/no feedback) on the learning of two different time-out lengths were compared. We measured the response time (RT) from the time-out occurrence to the time of the users action. Error rates and the development of the RTs in different schemes were used as measures of learning. We also studied if the users learned to estimate the time-out lengths, or if they just reacted to the available feedback. There were three main findings. Without feedback, RTs had a great variation. Auditory feedback enabled faster RTs than visual feedback. Finally, we found evidence of short-term learning, but not much of a lasting effect. The possible application of adapting time-out length to user RT is discussed.     

Computational support to record and re-experience visits

Information technology research has mainly focussed on supporting visitors with guides, whilst a lot of opportunities for the development of technology for collecting, manipulating and re-travelling through material from the visits remain unexplored. On the basis of observations from a specific setting, we have developed prototype technology to combine multimedia content with position information. In particular, we developed mobile support to record and organise multimedia using the walked path in order to preserve more of the experience of the visit. We created tools to edit and store multimedia paths. Additional components make it possible to configure a mixed-media environment to navigate a multimedia path, using such physical interfaces as gesturing, and link the recorded media to other artefacts. When discussing field observations of current practices and prototype trials, we investigate what kind of functionality is needed to support the whole activity of collecting, manipulating and playing multimedia content in combination with position information.     

Interface resistance

Interface resistance is studied by using the Landauer formula which relates the resistance to the quantum mechanical transmission coefficient. A simple rederivation of the Landauer formula is given. Using a step-like potential barrier as a model for the metal-semiconductor contact an analytical expression for the effective Richardson constant is derived. As an other application the grain boundary resistance in polycrystalline semiconductors is studied. The short-range potential fluctuation associated with the grain boundary is described by a rectangular potential barrier. The results for the grain boundary limited mobility cover both the strong and weak scattering regimes.     

Foreperiod and simple reaction time.

Reviews studies of simple visual and auditory reaction processes published since W. H. Teicher (1954), with emphasis on the preparatory phase of these processes, particularly the foreperiod (FP). The 1st section consists of the analysis of actual FP variables; duration, regularity, range, distribution, and preceding FPs. The 2nd section deals with factors affecting the relation between FP and reaction time (RT): (a) the modality, intensity, probability, and duration of the warning signal and reaction stimulus (RS) and (b) the speed–accuracy trade-off. It is suggested that the S's expectancy (momentary probability of the immediate delivery of the RS) is the most important determinant of the preparation to respond to the RS at any moment during a trial and, hence, of RT. Many factors exert their influence on preparation through their effect on expectancy. Other factors have a direct influence on preparation: short-term exhaustion and fatigue, immediate arousal evoked by intense auditory stimuli, the S's stimulus criterion, the speed–accuracy trade-off, and fluctuation in motor preparedness owing to inaccuracies in the control of motor preparation. (4? p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)