Magnesiumhydroksidialkalin käytön vaikutukset päällystämättömän aikakauslehtipaperin valmistukseen

Magnesiumhydroksidin on havaittu soveltuvan natriumhydroksidin korvaajaksi mekaanisen massan peroksidivalkaisun alkalina. Työssä selvitettiin, miten magnesiumhydroksidi vaikuttaa paperin valmistukseen ja valmiin paperin ominaisuuksiin. Laboratoriokokeet osoittivat magnesiumhydroksidin soveltuvan mekaanisen massan peroksidivalkaisun alkaliksi, sillä vaaleustavoite saavutettiin sen avulla. Valkaistun massan varaustila, johtokyky sekä ζ -potentiaali laskivat magnesiumhydroksidin vaikutuksesta. Nämä johtivat huomattavasti korkeampaan paperin täyteaineretentioon. Massan vedenpidätyskyky kasvoi korvattaessa natriumhydroksidi magnesiumhydroksidilla. Arkkien ominaisuuksista vetoindeksi, valonsirontakerroin ja taivutusjäykkyys kasvoivat. Kaikki edellä mainitut ominaisuudet viittaavat siihen, että magnesiumhydroksidin käyttö parantaa hienoaineen sitoutumista paperiin.

Magnesium hydroxide-based peroxide bleaching of high-brightness mechanical pulps

A high final brightness is desired in most paper and board products. This requires bleaching processes that are able to produce high-brightness pulps. Mechanical pulps are widely bleached for high brightness using alkaline hydrogen peroxide with traditional sodium hydroxide and sodium silicate as additives. With high doses however, peroxide bleaching causes high organic loads in the mill effluent and anionic trash carry-over to papermaking. To alleviate the problems that arise from the use of sodium-based additives in peroxide bleaching, interest in the use of alternative magnesium-based chemicals has increased. In this study, a new, technical high-purity magnesium hydroxide-based bleaching additive was evaluated on laboratory-scale, pilot-scale and mill-scale experiments and trials for its ability to produce a high brightness in peroxide bleaching without the known problems of sodium-based chemicals. The key findings of this study include: a high brightening potential of peroxide bleaching using the Mg(OH)2-based additive, significant reductions (40-70%) in all categories of environmental load, and cationic demand lowered by 60-70% in bleached pulp with no loss in strength properties or in sheet bulk. When used in TMP refiner bleaching, the Mg(OH)2-based additive resulted in savings in specific energy consumption and provided a good bleaching response.

Clinical evaluation and induced corneal vascularization study by native and anionic collagen membranes in rabbits corneas

PURPOSE: To evaluate the corneal vascularization (CV) and the clinical aspects induced by interlamellar graft with native (NCM) and anionic (ACM) collagen membranes in rabbits corneas. METHODS: An interlamellar graft with a 0.25 x 0.25 cm NCM (group 1) or ACM (group 2) fragment was performed in the right eye (treated eye). In the left eye, an estromal tunnel was done (control eye). Sixteen rabbits were used, and they were subdivided into two experimental groups of eight animals each. The clinical evaluation was performed at the 1st, 3rd, 7th, 15th and 30th postoperative days. Corneal vascularization analysis was performed after 30 days by the Images Analizator System Leica Qwin-550®. RESULTS: After 7 days, corneal vascularization was observed at about 2.25 ± 0.71 mm (NCM) and at about 1.0 ± 1.69 mm (ACM), respectively, from the limbus in direction to the central cornea. After 15 days, CV increased in both groups (5.25 ± 1.03 mm - NCM; 2.0 ± 2.39 mm - ACM) and then progressively decreased until day 30 (2.25 ± 2.10 mm - NCM; 0.75 ± 2.12 mm - ACM). The statistical analysis indicated that the averages of the distances from the limb vessels to the grafts observed after 7 and 15 days had not differed statistically (p=0.17), and after 15 and 30 postoperative days had a tendency to differ statistically (p=0.09). The control eyes did not present any changes. CONCLUSION: The interlamellar graft with native and anionic collagen membranes induced corneal vascularization when applied to rabbit corneas, but anionic collagen membrane induced a smaller corneal vascularization when compared to native collagen membrane. Although further studies are required, the results found in this study demonstrated the usefulness of interlamellar graft with native and anionic collagen membranes in keratoplasties. These membranes consists in one more graft option for the surgical treatment of corneal repair in rabbits and others animals, when other forms of medical and surgical treatment are not effective.

Animação Viral, Vanguarda Trash e o Capital Simbólico dos nossos Piores Defeitos: a Ideologia de Bruno Aleixo

"Bruno Aleixo" is a viral animation character, created by the Portuguese collective GANA, that surfaced online in 2008. Their animation works have meanwhile crossed onto the most diverse media, and have been branching out in multiple webs of narratives, constantly referring to each other, as well as constantly quoting disparate references such as film classics, chatrooms and TV ads for detergents. This paper attempts a triple analysis of this object of study: the ways in which technology has been fostering non-linear narratives while widening the available aesthetic spectrum, the ways in which processes of cultural consumerism are being reinvented in light of the web 2.0, and the use of "pseudo-nonsense" as a process of oblique cultural psychoanalysis. We will further attempt to demonstrate how new media and web networks have been contributing to a fragmentation of audiences, as well as a blurring between dominant cultures and sub-cultural phenomena; and we will end by positing that the structural principles behind the "Bruno Aleixo" series can be applied in social and cultural contexts situated at the opposite end of the spectrum of traditional expectations regarding Animation.

Solid contact PVC membrane electrodes based on neutral or charged carriers for the selective reading of anionic sulfamethoxazole and their application to the analysis of aquaculture water

Sulfamethoxazole (SMX) is among the antibiotics employed in aquaculture for prophylactic and therapeutic reasons. Environmental and food spread may be prevented by controlling its levels in several stages of fish farming. The present work proposes for this purpose new SMX selective electrodes for the potentiometric determination of this sulphonamide in water. The selective membranes were made of polyvinyl chloride (PVC) with tetraphenylporphyrin manganese (III) chloride or cyclodextrin-based acting as ionophores. 2-nitrophenyl octyl ether was employed as plasticizer and tetraoctylammonium, dimethyldioctadecylammonium bromide or potassium tetrakis (4-chlorophenyl) borate was used as anionic or cationic additive. The best analytical performance was reported for ISEs of tetraphenylporphyrin manganese (III) chloride with 50% mol of potassium tetrakis (4-chlorophenyl) borate compared to ionophore. Nersntian behaviour was observed from 4.0 × 10−5 to 1.0 × 10−2 mol/L (10.0 to 2500 µg/mL), and the limit of detection was 1.2 × 10−5 mol/L (3.0 µg/mL). In general, the electrodes displayed steady potentials in the pH range of 6 to 9. Emf equilibrium was reached before 15 s in all concentration levels. The electrodes revealed good discriminating ability in environmental samples. The analytical application to contaminated waters showed recoveries from 96 to 106%.

Ditopic molecular architectures for the recognition of anionic species

Dissertation presented to obtain the Ph.D degree in Chemistry

Modelling and optimization of the ion exchange membrane bioreactor for removal of anionic pollutants from drinking water streams

Dissertação para obtenção do Grau de Doutor em Engenharia Química, especialidade de Engenharia Bioquímica

tagO is involved in the synthesis of all anionic cell-wall polymers in Bacillus subtilis 168.

Sequence homologies suggest that the Bacillus subtilis 168 tagO gene encodes UDP-N-acetylglucosamine:undecaprenyl-P N-acetylglucosaminyl 1-P transferase, the enzyme responsible for catalysing the first step in the synthesis of the teichoic acid linkage unit, i.e. the formation of undecaprenyl-PP-N-acetylglucosamine. Inhibition of tagO expression mediated by an IPTG-inducible P(spac) promoter led to the development of a coccoid cell morphology, a feature characteristic of mutants blocked in teichoic acid synthesis. Indeed, analyses of the cell-wall phosphate content, as well as the incorporation of radioactively labelled precursors, revealed that the synthesis of poly(glycerol phosphate) and poly(glucosyl N-acetylgalactosamine 1-phosphate), the two strain 168 teichoic acids known to share the same linkage unit, was affected. Surprisingly, under phosphate limitation, deficiency of TagO precludes the synthesis of teichuronic acid, which is normally induced under these conditions. The regulatory region of tagO, containing two partly overlapping sigma(A)-controlled promoters, is similar to that of sigA, the gene encoding the major sigma factor responsible for growth. Here, the authors discuss the possibility that TagO may represent a pivotal element in the multi-enzyme complexes responsible for the synthesis of anionic cell-wall polymers, and that it may play one of the key roles in balanced cell growth.

Anionic Sites, Fucose Residues and Class I Human Leukocyte Antigen Fate During Interaction of Toxoplasma gondii with Endothelial Cells

Toxoplasma gondii invades and proliferates in human umbilical vein endothelial cells where it resides in a parasitophorous vacuole. In order to analyze which components of the endothelial cell plasma membrane are internalized and become part of the parasitophorous vacuole membrane, the culture of endothelial cells was labeled with cationized ferritin or UEA I lectin or anti Class I human leukocytte antigen (HLA) before or after infection with T. gondii. The results showed no cationized ferritin and UEA I lectin in any parasitophorous vacuole membrane, however, the Class I HLA molecule labeling was observed in some endocytic vacuoles containing parasite until 1 h of interaction with T. gondii. After 24 h parasite-host cell interaction, the labeling was absent on the vacuolar membrane, but presents only in small vesicles near parasitophorous vacuole. These results suggest the anionic site and fucose residues are excluded at the time of parasitophorous vacuole formation while Class I HLA molecules are present only on a minority of Toxoplasma-containig vacuoles.

Evaluation of uptake and transport of cationic and anionic ultrasmall iron oxide nanoparticles by human colon cells

Nanoparticles (NPs) are in clinical use or under development for therapeutic imaging and drug delivery. However, relatively little information exists concerning the uptake and transport of NPs across human colon cell layers, or their potential to invade three-dimensional models of human colon cells that better mimic the tissue structures of normal and tumoral colon. In order to gain such information, the interactions of biocompatible ultrasmall superparamagnetic iron oxide nanoparticles (USPIO NPs) (iron oxide core 9-10 nm) coated with either cationic polyvinylamine (aminoPVA) or anionic oleic acid with human HT-29 and Caco-2 colon cells was determined. The uptake of the cationic USPIO NPs was much higher than the uptake of the anionic USPIO NPs. The intracellular localization of aminoPVA USPIO NPs was confirmed in HT-29 cells by transmission electron microscopy that detected the iron oxide core. AminoPVA USPIO NPs invaded three-dimensional spheroids of both HT-29 and Caco-2 cells, whereas oleic acid-coated USPIO NPs could only invade Caco-2 spheroids. Neither cationic aminoPVA USPIO NPs nor anionic oleic acid-coated USPIO NPs were transported at detectable levels across the tight CacoReady? intestinal barrier model or the more permeable mucus-secreting CacoGoblet? model.

Evaluation of uptake and transport of cationic and anionic ultrasmall iron oxide nanoparticles by human colon cells.

Nanoparticles (NPs) are in clinical use or under development for therapeutic imaging and drug delivery. However, relatively little information exists concerning the uptake and transport of NPs across human colon cell layers, or their potential to invade three-dimensional models of human colon cells that better mimic the tissue structures of normal and tumoral colon. In order to gain such information, the interactions of biocompatible ultrasmall superparamagnetic iron oxide nanoparticles (USPIO NPs) (iron oxide core 9-10 nm) coated with either cationic polyvinylamine (aminoPVA) or anionic oleic acid with human HT-29 and Caco-2 colon cells was determined. The uptake of the cationic USPIO NPs was much higher than the uptake of the anionic USPIO NPs. The intracellular localization of aminoPVA USPIO NPs was confirmed in HT-29 cells by transmission electron microscopy that detected the iron oxide core. AminoPVA USPIO NPs invaded three-dimensional spheroids of both HT-29 and Caco-2 cells, whereas oleic acid-coated USPIO NPs could only invade Caco-2 spheroids. Neither cationic aminoPVA USPIO NPs nor anionic oleic acid-coated USPIO NPs were transported at detectable levels across the tight CacoReady? intestinal barrier model or the more permeable mucus-secreting CacoGoblet? model.

Effect of anionic salts in concentrate mixture on some blood and urine minerals, acid-base balance and feed intake of dry pregnant cows on grass silage based feeding with high calcium intake

Selostus: Kationi-anionitasapaino ummessaolevien lypsylehmien säilörehuruokinnassa kalsiumin saannin ollessa runsas