Acid Hydrogen Peroxide Treatment of Norway Spruce TMP: The Effect of an Extended pH Range when Catalyzed by Free Ferrous and Free or EDG/EDTA-Chelated Ferric Ions

The influence of different types of iron salts (i.e., ferrous or ferric cations with sulphate, nitrate or chloride anions) on the reaction between coarse thermomechanical pulp and acid hydrogen peroxide (Fenton chemistry) was studied when the initial pH was 3.2 and 5.3. Also, ferric ions chelated with EDTA or EDG at different molar ratios were compared with ferrous sulphate when the initial pH was extended from about 3 to 8. Different anions of ferric ion salt gave a similar catalytic effect. At an initial pH of 7–8, the ferric-EDTA catalyzed reaction resulted in similar or higher hydrogen peroxide consumption and more detectable hydroxyl radicals than the ferrous sulphate catalyzed reaction, but less reaction with the pulp was indicated. Between pH 5–8, using Fe-EDG as a catalyst gave higher hydrogen peroxide consumption and more detectable hydroxyl radicals than if using ferrous sulphate; however, the measured effect on the pulp was similar or less.     

Effect of the Degree of Phosphorylation on the Crystallinity of Native Potato Starch

X-ray diffraction technique, combined with digital image processing was used to compare the crystallinity of native starch from a number of potato varieties, differing in the degree of phosphorylation. The crystallinity was found to decrease linearily with an increased degree of phosphorylation. Based on earlier observations of the gelatinization enthalpies, it was assumed that the C-6 phosphates, which have an orientation out of the α-helices disturb the crystallization of the amylopectin during the starch synthesis. The C-3 phosphates, which are located in the interior parts of the α-helices, are not believed to interfere with the crystal structure.     

Reinvestigation of the antioxidant properties of conjugated linoleic acid

Despite repeated suggestions that antioxidant activity of conjugated linoleic acid (CLA), a collective of conjugated dienoic isomers of linoleic acid, underlies its reported anticarcinogenic and antiatherosclerotic effects, the antioxidant properties of CLA remain ill-defined. Therefore, this study was undertaken to gain more insight into the mechanism of potential CLA antioxidant activity. It was tested whether CLA could protect membranes composed of 1-palmitoyl-2-linoleoyl phosphatidylcholine (PLPC) from oxidative modification under conditions of metal ion-dependent or-independent oxidative stress. Progress of oxidation was determined by direct spectrophotometric measurement of conjugated diene formation and by gas chromatographic/mass spectrometric analysis of fatty acids. The oxidative susceptibility of CLA was higher than that of linoleic acid, and comparable to arachidonic acid. When oxidation of PLPC (1.0 mM) was initiated using the lipid-soluble 2,2′-azobis(2,4-dimethylvaleronitrile) or the water-soluble 2,2′-azobis(2-amidinopropane) hydrochloride, the radical scavengers vitamin E and butylated hydroxytoluene (BHT) at 0.75 μM efficiently inhibited PLPC oxidation, as evident from a clear lagphase. In contrast, 0.75 μM CLA did not have any significant effect on PLPC oxidation. Inhibition of PLPC oxidation by higher concentrations of CLA appeared due to competition, not to an antioxidant effect. When oxidation of PLPC was initiated by hydrogen peroxide/Fe²⁺ (500 μM/0.05–20 μM), both vitamin E (1 μM) and ethylene glycol-bis(aminoethyl ether) tetraacetic acid (50 μM) efficiently inhibited PLPC oxidation. However, CLA (1–50 μM) did not show a clear protective effect under any of the conditions tested. We conclude that CLA, under these test conditions, does not act as an efficient radical scavenger in any way comparable to vitamin E or BHT. CLA also does not appear to be converted into a metal chelator under metal-ion dependent oxidative stress, as had previously been suggested. On the basis of our observations, a role for CLA as an antioxidant does not seem plausible.     

A Study of Surface Wetting When Coating Paper

Abstract

The objective of this work will be to look at basic micro-level simulations of liquid state and movement. Defining liquid movement at fiber-coating boundaries is essential when modeling surface wetting of paper fibers. Drying studies have shown that chemical additives in base paper or coating color may reduce or increase quality, productivity, and energy efficiency considerably. The latest question is, Which are the factors that are significantly influencing liquid movement at fiber-coating boundaries? A phenomenon of less liquid drainage at lower paper moisture content is studied in this work together with the fiber hornification process. Fiber hornification is a complex change in the physicochemical properties of the fiber surface and the state of boundary molecules. Another important objective is to show how hornification may be accounted for in basic calculations. This while, printing properties of paper (mottling, etc.), may then be connected to the formation of the base paper and its drying history, explaining in more detail the importance of microlevel physicochemical property changes at fiber surfaces.     

Interactions of polymers and organic admixtures on portland cement hydration

Interaction of polymers and other organic admixtures on Portland cement hydration is reviewed. This has been compiled in a systematic way. First hydration of Portland cement is described in short. Later, interaction with 4 important components of Portland cement is discussed. Finally interphase effects in polymer modified hydraulic cement are discussed. It is concluded that polymers and organic admixtures interact with the components of Portland cement when they come in contact with water. This interaction is due to ionic binding, causing cross-links which inhibit the film formation property of polymers and influence considerably the crystallisation process during the hardening of concrete. Some low molecular weight organic substances also have a considerable influence on Portland cement during its reaction with water.     

Characterization of activated sludge flocs by confocal laser scanning microscopy and image analysis

In this study we present a new approach to determine volumes, heterogeneity factors, and compositions of the bacterial population of activated sludge flocs by 3D confocal imaging. After staining the fresh flocs with fluorescein-isothiocyanate, 75 stacks of images (containing approx. 3000 flocs) were acquired with a confocal laser scanning microscope. The self-developed macro 3D volume and surface determination for the KS 400 software package combined the images of one stack to a 3D image and calculated the real floc volume and surface. We determined heterogeneity factors like the ratio of real floc surface to the surface of a sphere with the respective volume and the fractal dimension (D(f)). According to their significant influence on floc integrity and quality, we also investigated the chemical composition of flocs and quantified their bacterial population structure by using group-specific rRNA-targeted probes for fluorescence in situ hybridization. By a settling experiment we enriched flocs with poor settling properties and determined the above-mentioned parameters. This approach revealed shifts in floc volume, heterogeneity, and bacterial and chemical composition according to the settling quality of the flocs.     

Degradation of phthalate esters in an activated sludge wastewater treatment plant

Efficient removal of phthalate esters (PE) in wastewater treatment plants (WWTP) is becoming an increasing priority in many countries. In this study, we examined the fate of dimethyl phthalate (DMP), dibutyl phthalate (DBP), butylbenzyl phthalate (BBP), and di-(2-ethylhexyl) phthalate (DEHP) in a full scale activated sludge WWTP with biological removal of nitrogen and phosphorus. The mean concentrations of DMP, DBP, BBP, and DEHP at the WWTP inlet were 1.9, 20.5, 37.9, and 71.9 μg/L, respectively. Less than 0.1%, 42%, 35%, and 96% of DMP, DBP, BBP, and DEHP was associated with suspended solids, respectively. The overall microbial degradation of DMP, DBP, BBP, and DEHP in the WWTP was estimated to be 93%, 91%, 90%, and 81%, respectively. Seven to nine percent of the incoming PE were recovered in the WWTP effluent. Factors affecting microbial degradation of DEHP in activated sludge were studied using [U-¹⁴C-ring] DEHP as tracer. First order rate coefficients for aerobic DEHP degradation were 1.0×10⁻², 1.4×10⁻², and 1.3×10⁻³ at 20, 32, and 43 °C, respectively. Aerobic degradation rates decreased dramatically under aerobic thermophilic conditions (<0.1×10⁻² h⁻¹ at 60 °C). The degradation rate under anoxic denitrifying conditions was 0.3×10⁻² h⁻¹, whereas the rate under alternating conditions (aerobic-anoxic) was 0.8×10⁻² h⁻¹. Aerobic DEHP degradation in activated sludge samples was stimulated 5-9 times by addition of a phthalate degrading bacterium. The phthalate degrading bacterium was isolated from activated sludge, and maintained a capacity for DEHP degradation while growing on vegetable oil. Collectively, the results of the study identified several controls of microbial PE degradation in activated sludge. These controls may be considered to enhance PE degradation in activated sludge WWTP with biological removal of nitrogen and phosphorus.     

Improving SFR economics through innovations from thermal design and analysis aspects

Achieving economic competitiveness as compared to LWRs and other Generation IV (Gen-IV) reactors is one of the major requirements to attract large-scale investment in commercial sodium cooled fast reactor (SFR) power plants. Advances in R&D for advanced SFR fuel and structural materials provide key long-term opportunities to improve SFR economics. In addition, other new opportunities are emerging to further improve SFR economics. This paper provides an overview on potential ideas from the perspective of thermal hydraulics to improve SFR economics. These include: (1) a new hybrid loop-pool reactor design to further optimize economics, safety, and reliability of SFRs with more flexibility, (2) a multiple-reheat and intercooling helium Brayton cycle to improve plant thermal efficiency and to reduce safety related overnight and operation costs, and (3) modern multi-physics thermal analysis methods to reduce analysis uncertainties and associated requirements for over-conservatism in reactor design. This paper reviews advances in all three areas and their potential beneficial impacts on SFR economics.     

Neutronic characterization of the MEGAPIE target

The MEGAPIE project aimed to design, build and operate a liquid metal spallation neutron target of about 1 MW beam power in the SINQ facility at the Paul Scherrer Institut (Villigen, Switzerland). This project is an important step in the roadmap towards the demonstration of the accelerator driven system (ADS) concept and high power liquid metal targets in general. Following the design phase, an experimental program was defined to provide a complete characterization of the facility by performing a “mapping” of the neutron flux at different points, from the center of the target to the beam lines. The neutronic performance of the target was studied using different experimental techniques with the goals of validating the Monte Carlo codes used in the design of the target; additionally, the performance was compared with the solid lead targets used before and after the MEGAPIE experiment.     

Active packaging of cheese with allyl isothiocyanate, an alternative to modified atmosphere packaging

The natural antimicrobial compound allyl isothiocyanate (AITC), found in mustard oil, is effective against cheese-related fungi both on laboratory media and cheese. Penicillium commune, Penicillium roqueforti, and Aspergillus flavus were more sensitive to AITC when it was added just after the spores had completed 100% germination and branching had started on Czapek yeast extract agar than were spores in the dormant phase. The use of 1 AITC label (Wasaouro interior labels, LD30D, 20 by 20 mm) in combination with atmospheric air in the packaging extended the shelf life of Danish Danbo cheese from 4 1/2 to 13 weeks. Two AITC labels extended the shelf life from 4 1/2 to 28 weeks. Both 1 and 2 labels in combination with modified atmosphere packaging extended the shelf life of the cheese from 18 to 28 weeks. This study showed that AITC was absorbed in the cheese, but it was not possible to detect any volatile breakdown products from AITC in the cheese. Cheese stored for up to 12 weeks with an AITC label had an unacceptable mustard flavor. The mustard flavor decreased to an acceptable level between weeks 12 and 28. Cheese stored in atmospheric air had a fresher taste without a CO2 off-flavor than did cheese stored in modified atmosphere packaging. AITC may be a good alternative to modified atmosphere packaging for cheese. The extended shelf life of cheese in the package is very desirable: the cheese can be transported longer distances, and the packaging can be used for the final maturing of the cheese. Furthermore, AITC can address problems such as pinholes and leaking seals in cheese packaging.