Chemical sulfate attack performance of partially exposed cement and cement + fly ash paste

When concrete elements are partially exposed to sulfate rich environment, the upper part of concrete in contact with air will be deteriorated more severely than the underground part. Fly ash additions seem to accelerate the collapse of concrete in such an environment. Although concrete technologists attribute concrete damage mainly to salt crystallization or physical sulfate attack, the influence of chemical sulfate attack cannot be neglected and should also be studied.The objective of this paper is twofold. First, pore solution expression test was conducted to squeeze pore solution of different parts of cement paste partially exposed to Na₂SO₄ solution. The sulfate concentration and pH value of pore solution were measured. Results showed that the sulfate concentration of the pore solution in the upper part of paste in contact with air was much higher than in the lower submerged part. Fly ash additions could draw more sulfates into the paste in a shorter time, forming a higher concentration sulfate pore solution than in normal concrete.The second test was designed to simulate the effect of severe exposure condition on reactive products of cement paste. Pure cement and cement + fly ash (25% dosage) pastes were immersed in 5%, 15% and 30% at 30 °C and 15% at 40 °C Na₂SO₄ solutions. Thermogravimetric analysis was used to analyze the reaction products of the paste. The results indicate that more ettringite and gypsum were formed in cement + fly ash paste than pure cement paste.     

Program management and the creative art of coopetition: Dealing with potential tensions and synergies between spatial development projects

Public ambitions have traditionally been implemented by line managers. Project management has become more prevalent in recent decades, especially in the domain of spatial investments. Recently, a new branch of management has emerged: program management. This can be seen as an attempt to overcome the fragmentation caused by several autonomous project organizations working side by side in the larger regional system.     

Benzene, alkylated benzenes, chlorinated hydrocarbons and monoterpenes in snow/ice at Jungfraujoch (46.6 degrees N, 8.0 degrees E) during CLACE 4 and 5

Benzene, alkylated benzenes, chlorinated hydrocarbons and monoterpenes were measured in snow/ice collected directly in-cloud at Jungfraujoch (3580 m asl) in February and March 2005 and 2006 during the CLoud and Aerosol Characterization Experiments CLACE 4 and CLACE 5. Melted snow/ice samples were analyzed by headspace-solid-phase-dynamic-extraction (HS-SPDE) followed by gas chromatography/mass spectrometry (GC/MS). Generally, there was a tendency in the results that higher concentrations were found after longer precipitation-free periods, suggesting that higher concentrations in snow/ice may be caused by the washout effect of precipitation. High concentration variations in snow/ice samples taken at the same time at the same place highlight the heterogeneous nature of snow/ice. Air concentrations calculated by scavenging ratios and measured snow/ice values markedly exceed the typically reported concentrations of benzene and alkylbenzenes in air (Li Y, Campana M, Reimann S, Schaub KS, Staehlin J, Peter T. Hydrocarbon concentrations at the alpine mountain sites Jungfraujoch and Arosa. Atmos Environ 2005;39:1113-27). This argues for an efficient snow/ice scavenging of those compounds from the atmosphere during precipitation formation.     

The ongoing energy transition: Lessons from a socio-technical,multi-level analysis of the Dutch electricity system (1960–2004)

Energy transitions to sustainability receive much interest in politics and science. Using a socio-technical and multi-level theory on transitions, this article draws important lessons from a long-term analysis of the Dutch electricity system. The article analyses technical developments, changes in rules and visions, and social networks that support and oppose renewable options. The article is multi-level because it looks at novel renewable energy technologies and structural trends in the existing electricity regime. The analysis shows that an energy transition, with roots in the 1960s and 1970s, is already occurring, but driven mainly by liberalisation and Europeanisation. Environmental aspects have become part of this ongoing transition, but do not form its main driver. Many barriers exist for a sustainability transition, but there are also some opportunities. A long-term analysis of renewable niche-innovation trajectories (wind, biomass, PV) provides lessons about socio-technical dynamics, problems and windows of opportunity.     

Solubility and toxicity of antimony trioxide (Sb2O3) in soil

Antimony trioxide (Sb2O3) is a widely used chemical that can be emitted to soil. The fate and toxicity of this poorly soluble compound in soil is insufficiently known. A silt-loam soil (pH 7.0, background 0.005 mmol Sb kg(-1)) was amended with Sb2O3 at various concentrations. More than 70% of Sb in soil solution was present as Sb(V) (antimonate) within 2 days. The soil solution Sb concentrations gradually increased between 2 and 35 days after Sb2O3 amendment but were always below that of soils amended with the more soluble SbCl3 at the lower Sb concentrations. The soil solution Sb concentrations in freshly amended SbCl3 soils (7 days equilibration) were equivalent to those in Sb2O3-amended soils equilibrated for 5 years at equivalent total soil Sb. Our data indicate that the Sb solubility in this soil was controlled by a combination of sorption on the soil surface, Sb precipitation at the higher doses, and slow dissolution of Sb2O3, the latter being modeled with a half-life ranging between 50 and 250 days. Toxicity of Sb to plant growth (root elongation of barley, shoot biomass of lettuce) or to nitrification was found in soil equilibrated with Sb2O3 (up to 82 mmol Sb kg(-1)) for 31 weeks with 10% inhibition values at soil solution Sb concentrations of 110 microM Sb or above. These concentrations are equivalent to 4.2 mmol Sb per kg soil (510 mg Sb kg(-1)) at complete dissolution of Sb2O3 in this soil. No toxicity to plant growth or nitrification was evident in toxicity tests starting one week after soil amendment with Sb2O3, whereas clear toxicity was found in a similar test using SbCl3. However, these effects were confounded by a decrease in pH and an increase in salinity. It is concluded that the Sb(V) toxicity thresholds are over 100-fold larger than background concentrations in soil and that care must be taken to interpret toxicity data of soluble Sb(III) forms due to confounding factors.     

The effects of the myostatin g+6723G>A mutation on carcass and meat quality of lamb

This study evaluated the effects of the myostatin g + 6723G > A mutation on carcass and meat quality traits of lamb (AA: n = 5; AG: n = 8; GG: n = 9). Dressing percentage was positively affected by the mutation with homozygotes for the mutation having the highest yield. Regarding carcass composition, there was a significant increase in the proportional weights of the loin and hindquarter muscles. Objective meat quality traits of the M. longissimus lumborum (LL) and M. semimembranosus (SM) were not significantly affected. For the SM, toughness (shear force and compression) tended to be lowest for homozygotes for the mutation. The myostatin g + 6723G > A mutation did not affect sensory meat quality traits of grilled steaks for the LL, but resulted in a significant improvement in eating quality for the SM. Given the number of animals in this study, the robustness of the outcome of this study with regard to the effects on meat quality and its causes requires further investigation.     

Understanding spatial concentrations of road accidents using frequent item sets

This paper aims at understanding why road accidents tend to cluster in specific road segments. More particularly, it aims at analyzing which are the characteristics of the accidents occurring in "black" zones compared to those scattered all over the road. A technique of frequent item sets (data mining) is applied for automatically identifying accident circumstances that frequently occur together, for accidents located in and outside "black" zones. A Belgian periurban region is used as case study. Results show that accidents occurring in "black" zones are characterized by left-turns at signalized intersections, collisions with pedestrians, loss control of the vehicle (run-off-roadway) and rainy weather conditions. Accidents occurring outside "black" zones (scattered in space) are characterized by left turns on intersections with traffic signs, head-on collisions and drunken road user(s). Furthermore, parallel collisions and accidents on highways or roads with separated lanes, occurring at night or during the weekend are frequently occurring accident patterns for all accident locations. These exploratory results show the potentiality of the frequent item set method in addition to more classical statistical techniques, but also suggest that there is no unique countermeasure for reducing the number of accidents.     

Computational estimation of the composition of fat/oil mixtures containing interesterifications from gas and liquid chromatography data

A mathematical framework is introduced that relates analytical data to the composition of fat and oil mixtures. Within this framework, the noise characteristics of four common analytical techniques [FAME, FAME2-pos, CN (carbon number), and AgLC] were investigated and modeled by both additive and multiplicative noise terms. The fat blend recognition (FBR) performance was investigated under these two types of noise, both qualitatively and quantitatively. Furthermore, an extension is proposed that makes it possible to detect interesterifications of unknown mixtures, which was impossible before. The proposed procedure is divided into a qualitative estimation stage, which is focused on identifying the raw materials (RM), followed by a quantitative estimation stage, which is focused on quantifying the levels of the RM identified. We compared two qualitative strategies and four quantitative methods for their ability to correctly estimate simulated mixtures under the noise characteristics determined. The comparison of methods was extended to actual mixtures, revealing promising results. Our analysis presents multiple directions for further adulteration and FBR studies.     

Anticipation and visual search behaviour in expert soccer goalkeepers

A novel methodological approach is presented to examine the visual search behaviours employed by expert goalkeepers during simulated penalty kick situations in soccer. Expert soccer goalkeepers were classified as successful or unsuccessful based on their performance on a film-based test of anticipation skill, thereby allowing an intra-group comparison of visual search behaviour on the task. The anticipation test required participants to move a joystick in response to penalty kick situations presented on a large screen. The proportion of penalties saved was assessed as well as the frequency and time of initiation of joystick corrections. Visual search behaviour was examined using a portable eye movement registration system. The successful experts were more accurate in predicting the height and direction of the penalty kick, waited longer before initiating a response and appeared to spend longer periods of time fixating on the non-kicking leg compared with the non-successful experts.