Reel-to-reel inline atmospheric plasma deposition of hydrophobic coatings

Plasma deposition equipment was developed and installed at a pilot extrusion coating line for reel-to-reel substrates. Hexamethyldisiloxane was used as a siloxane precursor for the atmospheric plasma deposition of siloxane coatings on substrates of three different categories: paper, polyethylene-coated paper, and textile materials (woven cotton fabric and polypropylene nonwoven). SEM, H₂O contact angle measurements, heat sealability, and water vapor barrier measurements were carried out to characterize the composition and surface structure of the samples. The potential of the method and the equipment was shown by the coatings, ranging to micrometer scale. With selected samples, hydrophobic coating was shown to form at speeds up to 100 m/min.     

Combustion Properties of Birch (Betula pendula) Black Liquors From Sulfur-Free Pulping

Sulfur-free pulping has an environmental advantage over the traditional kraft process. This article describes the combustion properties of the black liquors produced from silver birch (Betula pendula) sawdust using three different cooking processes: two sulfur-free cooks (soda-anthraquinone and oxygen-alkali), and one reference kraft cook. It also considers the corresponding black liquors from an integrated forest biorefinery, in which a hot-water pretreatment of feedstock was performed prior to pulping. With the same cooking time, the total burning times for the sulfur-free black liquors were higher (15–55%) than those for the conventional kraft black liquors. However, no significant differences were noted between the total burning times for black liquors from pretreated feedstock and those from untreated feedstock. Especially in the case of untreated feedstock, the results showed that the kraft black liquors typically swelled more (25–45%) than the sulfur-free black liquors. It was further observed that the kraft and soda-anthraquinone black liquors from the untreated feedstock swelled more than those from the pretreated feedstock, while the oxygen-alkali black liquors swelled less.     

Long-term daily intake estimates of polychlorinated dibenzo-p-dioxins and furans, polychlorinated biphenyls and polybrominated diphenylethers from food in Finnish children: risk assessment implications

Food is contaminated by polychlorinated dibenzo-p-dioxins and furans (PCDD/F), polychlorinated biphenyls (PCB) and polybrominated diphenylethers (PBDE) worldwide. Previous data show elevated intakes in children. We determined intakes of POPs in Finnish children. Because no children-specific safe limit values exist, we used tolerable daily intakes (TDIs) set for adults by international expert bodies to examine the proportion of the study population that exceed those limits. We utilised dietary monitoring data with food consumption of Finnish boys and girls aged 1-6 years, measured the contaminant concentrations in all the main food items and calculated age-specific contaminant sum and congener-specific long-term daily intake levels. Our food intake and contaminant data correspond to years 2002-2005. The long-term upper-bound dioxin intakes ranged between 0.1 and 12.8?pg WHO(PCDD/F-PCB)-TEQ/kg bw/d (min and max). An immediate TDI for WHO(PCDD/F-PCB)-TEQs of 4.0?pg/kg?bw/d were exceeded by 2.5%-7.5% of the children. PBDE long-term upper-bound intake was between 0.1 and 5.8?ng/kg bw/d (min and max). Congener-specific analyses indicated a typical Finnish adult exposure pattern of the children to PCDD/Fs, PCBs and PBDEs. The highest POP intakes were observed in children aged 3 years. Long-term daily PCDD/F, PCB and PBDE intakes among Finnish children varied greatly between individuals and ages. In each age group of the study population, there was a proportion of children with their WHO(PCDD/F-PCB)-TEQ intake exceeding considered safe limits set for adults. Based on the exposure profile reported herein, children should be clearly considered as a specific sub-population in food-mediated contaminant risk assessment.     

Characterization of ten H2 producing cyanobacteria isolated from the Baltic Sea and Finnish lakes

The genetic background and activities of the enzymes involved in H₂ production were investigated from ten distinct H₂ producing cyanobacteria, revealed by a recent screening. All strains are N₂-fixing, filamentous and heterocystous. Southern hybridization revealed that the tested strains possess the genes encoding the conventional nitrogenase (nifHDK1), and lack the alternative nitrogenases. The high H₂ production rate of these strains was shown not to be dependent on the presence of highly active nitrogenase or bidirectional hydrogenase enzymes. Moreover, most of the strains possessed a highly active uptake hydrogenase enzyme. We also examined the structure of the nif and hup operons encoding nitrogenase and uptake hydrogenase enzymes in the Calothrix 336/3 strain, the best H₂ producer in the screening. We concluded that the ability of the cyanobacteria to produce high levels of H₂ is not directly linked to the maximum capacities of the enzymes involved in H₂ production.     

Toxicological effects of dehydroabietic acid (DHAA) on the trout, Salmo gairdneri Richardson, in fresh water

Toxicological and physiological effects of dehydroabietic acid (DHAA), a major poison to fishes in pulp and paper mill effluents, were studied by two experiments with rainbow trout, Salmo gairdneri Richardson: in the first, fish were acutely exposed for 4 days to an average DHAA concentration of 1.2 mg l⁻¹ (Exp. I) and in the second for 30 days to an average of 20 μg DHAA l⁻¹ (Exp. II).Compared to the controls, fish of Exp. I displayed a decreased relative weight of liver, an increased blood haematocrit, and increased haemoglobin as well as plasma protein concentrations. The aspartate aminotransferase activity of heart muscle was significantly elevated, as was also the lactate dehydrogenase (LDH) of white muscle tissue. In the blood plasma, the proportion of muscle type LDH activity was simultaneously increased. UDP-glucuronyl-transferase activities of liver and kidney were strongly decreased. Results suggest an increased and altered use of body energy reserves, decreased plasma volume and impaired liver function.Fish of Exp. II showed an increased relative weight of spleen. In addition, liver and gill LDH shifted towards heart-type. We conclude that 20 μg l⁻¹ is close to the “minimum effective concentration” of DHAA to rainbow trout.     

Hydrogen-induced stress corrosion cracking studied by the novel tuning-fork test method

A novel tuning-fork test method was developed to study hydrogen-induced stress corrosion cracking of high-strength steels. Special tuning-fork specimens are designed to enable accurate stress adjustment via constant displacement under cathodic hydrogen charging conditions. In this study, the testing method is further developed, making the potentiostatic hydrogen charging possible through the modifications of the corrosion cell. Different direct-quenched, low- and medium-carbon steel grades, with a hardness range of 300–550 HBW, are investigated with both galvanostatic and potentiostatic hydrogen charging techniques. For each steel grade, the lowest fracture stress and highest no-fracture stress are determined. Both hydrogen charging techniques produce similar results, and it is observed that the fracture stress decreases with the increase in hardness. However, the potentiostatic technique produces larger differences between the lowest fracture stress results, thus having a better resolution.