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A rotary multi-bed active magnetic regenerator (AMR) device was modified to allow testing different fluid flow waveforms, with different blow fractions (i.e., the fraction of the AMR cycle when there is fluid flow in the regenerators). The different values of blow fraction were generated using different cam rings that actuate the poppet valves at the inlet and outlet of the regenerators, controlling how long the valves stay open and the number of valves open at the same time. Results showed that smaller blow fractions yield higher values of temperature span for fixed flow rate and cooling capacity, but lower values of coefficient of performance for the same conditions. An analysis of the shaft and pumping powers showed that shorter blow fractions cause higher pressure drop and higher torque oscillations and mechanical vibrations. The highest value of second-law efficiency of 19.1% was obtained for the largest blow fraction tested (80%). Designs for magnetic refrigerators where the fluid flow waveform can change during operation are also discussed in this paper. [ABSTRACT FROM AUTHOR]

In manufacture of cement clinker, mercury is introduced in the cement kiln system via the fuels and as constituents in the raw matends, i.e., limestone, iron ore, etc. The permissible emission of Hg to air is very low (0.05 mg/Nm3) due to its toxicity. Thus, it is important to know how mercury distributes and behaves in the kiln system. The objective of the study was to measure the distribution of mercury in the kiln system, to measure the hold up time of Hg, to measure the portion of emission through the chimneys, and to see the dependence of the injection sites on these parameters. The results showed that the amounts of mercury being emitted through the exhaust gases were largely dependent on where it was injected. The residence time of mercury in the system was nevertheless long, after 10 hours it was still increase in the count rate of the mercury absorbed. There was also an immediate increase in the filter dust, but nothing could be measured in the clinker. This knowledge is neededfor the reduction of mercury emissions. [ABSTRACT FROM AUTHOR]

When oil fields fall during their lifetime below the bubble point gas comes out of solution. The key questions are at which saturation the gas becomes mobile (“critical gas saturation”) and what the gas mobility is, because mobile gas reduces the production of oil significantly. The traditional view is that the gas phase becomes mobile once gas bubbles grow or expand to a size where they connect and form a percolating path. For typical 3D porous media the saturation corresponding to this percolation limit is on the order of 20%. However, significant literature report on gas mobility below lower limits of percolation thresholds i.e. below 0.1%. A direct experimental insight for that is lacking because laboratory measurements are notoriously difficult since the formation of gas bubbles below the bubble point includes thermodynamic and kinetic aspects, and the pressure decline rates achievable in laboratory experiments are orders of magnitude higher than the decline rates in the field. Here we study the nucleation and transport of gas coming out of solution in-situ in 3D rock using X-ray computed micro tomography which allows direct visualization of the nucleation kinetics and connectivity of gas. We use either propane or a propane–decane mixture as model system and conduct pressure depletion in absence of flow finding that – consistent with the literature – observation of the bubble point in the porous medium is decreased and becomes pressure decline rate dependent because of the bubble nucleation kinetics. That occurs in single-component systems and in hydrocarbon mixtures. Pressure depletion in absence of flow results in critical gas saturations between 20 and 30% which is consistent with typical percolation thresholds in 3D porous structures. That does not explain experimentally observed critical gas saturations significantly below 20%. Also, the respective pore level fluid occupancy where pores are filled with either gas or liquid phase but not partially with both as in normal 2-phase immiscible systems rather diminishes connectivity of gas and liquid phases. This observation indicates that likely other mechanisms play a role in establishing gas mobility at saturations significantly below 20%. Experiments under flow conditions, where gas is injected near the bubble point suggest that diffusion may significantly contribute to the transport of gas and may even be the dominant transport mechanism at field relevant flow rates. The consequence of diffusive transport are compositional gradients where locally the composition is such gas nucleation may occur. That would lead to a disconnected but mobile gas distribution ahead of the convective front. Furthermore, diffusive exchange leads to ripening and anti-ripening effects which influences the distribution for which we see evidence in pressure depletion experiments but not so much at low rate gas injection. Respective relative permeability computed from the imaged fluid distributions using a lattice Boltzmann approach show distinctly different behavior between pressure depletion and flowing conditions. These findings suggest that capillarity in a gas–liquid hydrocarbon mixture is far more complex than in a 2-phase immiscible system. Capillarity is coupled to phase behavior thermodynamics and kinetics on a fast time scale and diffusion-dominated mechanisms such as ripening and anti-ripening effects at a slow time scale. While the consequences for the current experimental and field modelling approaches are not yet fully clear, this shows that more research is needed to fully understand these effects and their implications.

A major environmental issue is to understand how eutrophication processes, such as organic enrichment and hypoxia may act on the distribution patterns and bioavailability of contaminants to benthic organisms. An experiment with sediment organic C content (control vs enrichedwith concentrated phytoplankton) and oxygen level (normoxia vs 2-3 mg O2 l-1) as fixed factors, and 14C-B(a)P in benthic organisms and sediment as dependent variable, was conducted for 93 days. Three species of sediment-dwelling organisms with different feeding strategies (Amphiura filiformis, Nereis diversicolor and Abra alba) were chosen. Blue mussels (Mytilus edulis), kept in separate aquaria, were exposed to the outflowing water of the microcosms. Concentration of 14C-B(a)P in the sediment surface at the end of the experiment was significantly higher in the organically enriched sediments than in the control sediments. Accumulation of14C-B(a)P in A. filiformis and N. diversicolor was also higher in the presence of organic enrichment. Concentrations of 14C-B(a)P in M. edulis placed downstream of aquaria treated withorganic matter were also higher, indicating a higher leaching of bioavailable 14C-B(a)P from the enriched sediments. Hypoxia had no significant effect on the sediment distribution and bioaccumulation of 14C-B(a)P, and there was no significant interaction between hypoxia and organic enrichment. Our results support the concept of selective feeding on labile organic matter as a major exposure route of organic contaminants in benthic organisms. [ABSTRACT FROM AUTHOR]

The availability of labile organic matter and oxygen from the bottomwater are primary factors most likely to affect the accumulation of contaminants in benthic invertebrates. To test this hypothesis, a two-factor microcosm experiment was designed. Three species of sediment-dwelling organisms were kept in sediments spiked with 203Hg and 109Cd. Blue mussels were kept downstream in separatevessels. Different treatments were obtained by combination of two levels of organic carbon (enriched, not enriched) with two levels of oxygen (7-9 mg l-1 and 2-3 mg l-1) in the water flowing through the aquaria. After an experimental period of three months, gamma emission from the two isotopes were counted in samples of sediments, porewater and biota. The results showed initial retention of a labile fraction of Cd in the carbon-enriched sediments. Hg was retained to the same extent in all treatments and no significant loss from the sediment was observed during the experimental period. In theporewater, Hg was not detectable whereas the concentration of Cd wasconsistent with the levels predicted from low sulphide ion activities recorded on Ag|Ag2S electrodes and the solubility of CdS(s). Two-way ANOVA analyses revealed significant effects of carbon enrichment on bioaccumulation of both Cd and Hg. Significanteffects of oxygen level and oxygen-organic interactions were found for the bioaccumulation of Cd only. [ABSTRACT FROM AUTHOR]

In marine environments influenced by human activities, the sea-bed is a major recipient of both contaminants and organic matter. Deposition and recycling of contaminants from bottom sediments may be affected by the eutrophication status of the area. Contaminants and eutrophication factors may also interact to affect bioaccumulation as well asthe growth, health and reproduction of benthic organisms. Consequently, from an environmental management point of view, these interactions should be considered when decisions are made about input of contaminants and organic matter to the aquatic environment. In order to elucidate interaction patterns between eutrophication and contaminants, radio-labeled contaminants were applied in a large scale experiment performed at Marine Research Station Solbergstrand, situated by the Oslofjord, Norway. The continuous flow through experiment was performed in glass aquaria containing three sediment-dwelling species (Abra alba, Nereis diversicolor and Amphiura filiformis) placed in marine claysediments. Blue mussels (Mytilus edulis) were kept in separate downstream aquaria and exposed to the outflowing water from the sediment aquaria. In 12 contaminated aquaria the sediment was spiked with 203Hg (0.23 mg Hg kg-1 dry sediment), 109Cd (5 mg Cd kg-1) and 14C-benzo[a]pyrene (1 mg BaP kg-1). In 12 organically enriched aquaria, phytoplankton (2 mg C kg-1 dry sediment) was initially mixed into thesediment and two months later another batch corresponding to 20 g C m-2 was added to the aquaria. Finally, the concentration of oxygen was continuously lowered from 7-9 mg O2 l-1 in 12 well-oxygenated aquaria to 2.4-3.5 mg O2 l-1 in 12 low-oxic aquaria by purging the source water with nitrogen. Allowing three replicate aquaria for each treatment, all combinations of the two levels (high/low) of the three factors (contaminants, [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to determine whether minimum recommended moderate-to-vigorous physical activity (MVPA; 30-min bout of continuous moderate-intensity walking) is sufficient to counteract the detrimental effects of prolonged sitting on postprandial metabolism and if there are any effects of breaking up sitting with intermittent standing when achieving minimum recommended MVPA., Methods: Fourteen (n = 14) physically inactive healthy adult males underwent four intrahospital 27-h interventions: 9-h continuous sitting (SIT), 15-min standing bouts every 30 min during the 9-h sitting (STAND), 30-min moderate-intensity walking bout followed by 8.5 h of sitting (MVPA), and 30-min moderate-intensity walking bout followed by 15-min standing bouts every 30 min during 8.5 h of sitting (MVPA + STAND). Three standardized meals on intervention day (day 1) and breakfast the following day (day 2) were served., Results: Cumulative postprandial glucose response (incremental area under the curve) was lower in STAND versus SIT (↓27%, P = 0.04, effect size [ES] = -0.7) because of decreases in postprandial glucose after breakfast on day 1 (STAND vs SIT: ↓40%, P = 0.01, ES = -0.7) and day 2 (STAND vs SIT: ↓33%, P = 0.06, ES = -0.6). STAND did not affect postprandial insulin responses. Cumulative postprandial insulin response was lower in MVPA versus SIT (↓18%, P = 0.03, ES = -0.3) and MVPA + STAND versus SIT (↓26%, P = 0.02, ES = -0.4) because of expected exercise-induced decreases in postprandial insulin after breakfast on day 1 only (MVPA vs SIT: ↓36%, P = 0.003, ES = -0.7; MVPA + STAND vs SIT: ↓43%, P = 0.0001, ES = -0.8)., Conclusion: Breaking up prolonged sitting with nonambulatory standing across 9 h acutely reduced postprandial glycemic response during and the day after the intervention independent of insulin levels, whereas a 30-min MVPA bout did not.

Objective: The aim of this study is to investigate the association between five-year changes in occupational sitting and body mass index (BMI) in working adults., Methods: We analyzed data from The Danish Work Environment Cohort Study (2005 and 2010, n=3.482). Data on occupational sitting, weight, height and several potential confounders were self-reported. The association between change in occupational sitting (hours) (categorized as large decrease <-7.5, moderate decrease -7.5 to <-2.5, no change -2.5 to 2.5, moderate increase >2.5 to 7.5 and large increase >7.5) and change in BMI was explored by multiple linear regression analyses., Results: 43.0% men and 36.1% women had high occupational sitting time (≥25h per week) at baseline. 31.8% men and 27.2% women decreased while 30.0% men and 33.0% women increased occupational sitting. The proportion of obese (BMI≥30) increased almost 3% for both genders. BMI changed 0.13 (CI: 0.06; 0.20, p=0.0003), per category of change in occupational sitting in women, but no association was found in men., Conclusion: In women, there is a positive association between five-year changes in occupational sitting and BMI., (Copyright © 2015 Elsevier Inc. All rights reserved.)