Influence of plasma modification on surface properties and offset printability of coated paper

The properties of the paper surface play a crucial role in ensuring suitable quality and runnability in various converting and finishing operations, such as printing. Plasma surface modification makes it possible to modify the surface chemistry of paper without altering the bulk material properties. This also makes it possible to investigate the role of the surface chemistry alone on printability without influencing the porous structure of the pigment-coated paper. Since the porous structure of a pigment coating controls both ink setting and optical properties, surface chemical changes created by a plasma modification have a potential to decouple these two effects and to permit a better optimization of them both. The aim of this work was to understand the effects of plasma surface modification on paper properties, and how it influences printability in the sheet-fed offset process. The objective was to broaden the fundamental understanding of the role of surface chemistry on offset printing. The effects of changing the hydrophilicity/ hydrophobicity and the surface chemical composition by plasma activation and plasma coatings on the properties of coated paper and on ink-paper interactions as well as on sheet-fed offset print quality were investigated. In addition, the durability of the plasma surface modification was studied. Nowadays, a typical sheet-fed offset press also contains units for surface finishing, for example UVvarnishing. The role of the surface chemistry on the UV-varnish absorption into highly permeable and porous pigment-coated paper was also investigated. With plasma activation it was possible to increase the surface energy and hydrophilicity of paper. Both polar and dispersion interactions were found to increase, although the change was greater in the polar interactions due to induced oxygen molecular groups. The results indicated that plasma activation takes place particularly in high molecular weight components such as the dispersion chemicals used to stabilize the pigment and latex particles. Surface composition, such as pigment and binder type, was found to influence the response to the plasma activation. The general trend was that pilot-scale treatment modified the surface chemistry without altering the physical coating structure, whereas excessive laboratory-scale treatment increased the surface roughness and reduced the surface strength, which led to micro-picking in printing. It was shown that pilot-scale plasma activation in combination with appropriate ink oils makes it possible to adjust the ink-setting rate. The ink-setting rate decreased with linseed-oil-based inks, probably due to increased acid-base interactions between the polar groups in the oil and the plasma-treated paper surface. With mineral-oil-based inks, the ink setting accelerated due to plasma activation. Hydrophobic plasma coatings were able to reduce or even prevent the absorption of dampening water into pigmentcoated paper, even when the dampening water was applied under the influence of nip pressure. A uniform hydrophobic plasma coating with sufficient chemical affinity with ink gave an improved print quality in terms of higher print density and lower print mottle. It was also shown that a fluorocarbon plasma coating reduced the free wetting of the UV-varnish into the highly permeable and porous pigment coating. However, when the UV-varnish was applied under the influence of nip pressure, which leads to forced wetting, the role of the surface chemical composition seems to be much less. A decay in surface energy and wettability occurred during the first weeks of storage after plasma activation, after which it leveled off. However, the oxygen/carbon elemental ratio did not decrease as a function of time, indicating that ageing could be caused by a re-orientation of polar groups or by a contamination of the surface. The plasma coatings appeared to be more stable when the hydrophobicity was higher, probably due to fewer interactions with oxygen and water vapor in the air.

Recovery and refining of manganese as by-product from hydrometallurgical processes

The consumption of manganese is increasing, but huge amounts of manganese still end up in waste in hydrometallurgical processes. The recovery of manganese from multi-metal solutions at low concentrations may not be economical. In addition, poor iron control typically prevents the production of high purity manganese. Separation of iron from manganese can be done with chemical precipitation or solvent extraction methods. Combined carbonate precipitation with air oxidation is a feasible method to separate iron and manganese due to the fast kinetics, good controllability and economical reagents. In addition the leaching of manganese carbonate is easier and less acid consuming than that of hydroxide or sulfide precipitates. Selective iron removal with great efficiency from MnSO4 solution is achieved by combined oxygen or air oxidation and CaCO3 precipitation at pH > 5.8 and at a redox potential of > 200 mV. In order to avoid gypsum formation, soda ash should be used instead of limestone. In such case, however, extra attention needs to be paid on the reagents mole ratios in order to avoid manganese coprecipitation. After iron removal, pure MnSO4 solution was obtained by solvent extraction using organophosphorus reagents, di-(2-ethylhexyl)phosphoric acid (D2EHPA) and bis(2,4,4- trimethylpentyl)phosphinic acid (CYANEX 272). The Mn/Ca and Mn/Mg selectivities can be increased by decreasing the temperature from the commonly used temperatures (40 –60oC) to 5oC. The extraction order of D2EHPA (Ca before Mn) at low temperature remains unchanged but the lowering of temperature causes an increase in viscosity and slower phase separation. Of these regents, CYANEX 272 is selective for Mn over Ca and, therefore, it would be the better choice if there is Ca present in solution. A three-stage Mn extraction followed by a two-stage scrubbing and two-stage sulfuric acid stripping is an effective method of producing a very pure MnSO4 intermediate solution for further processing. From the intermediate MnSO4 some special Mn- products for ion exchange applications were synthesized and studied. Three types of octahedrally coordinated manganese oxide materials as an alternative final product for manganese were chosen for synthesis: layer structured Nabirnessite, tunnel structured Mg-todorokite and K-kryptomelane. As an alternative source of pure MnSO4 intermediate, kryptomelane was synthesized by using a synthetic hydrometallurgical tailings. The results show that the studied OMS materials adsorb selectively Cu, Ni, Cd and K in the presence of Ca and Mg. It was also found that the exchange rates were reasonably high due to the small particle dimensions. Materials are stable in the studied conditions and their maximum Cu uptake capacity was 1.3 mmol/g. Competitive uptake of metals and acid was studied using equilibrium, batch kinetic and fixed-bed measurements. The experimental data was correlated with a dynamic model, which also accounts for the dissolution of the framework manganese. Manganese oxide micro-crystals were also bound onto silica to prepare a composite material having a particle size large enough to be used in column separation experiments. The MnOx/SiO2 ratio was found to affect significantly the properties of the composite. The higher the ratio, the lower is the specific surface area, the pore volume and the pore size. On the other hand, higher amount of silica binder gives composites better mechanical properties. Birnesite and todorokite can be aggregated successfully with colloidal silica at pH 4 and with MnO2/SiO2 weight ratio of 0.7. The best gelation and drying temperature was 110oC and sufficiently strong composites were obtained by additional heat-treatment at 250oC for 2 h. The results show that silica–supported MnO2 materials can be utilized to separate copper from nickel and cadmium. The behavior of the composites can be explained reasonably well with the presented model and the parameters estimated from the data of the unsupported oxides. The metal uptake capacities of the prepared materials were quite small. For example, the final copper loading was 0.14 mmol/gMnO2. According to the results the special MnO2 materials are potential for a specific environmental application to uptake harmful metal ions.

Improving the usability of extruded wood-plastic composites by using modification technology

Using cellulosic reinforcement to produce plastic composites is a globally growing trend. One of such materials are wood-plastic composites, which are an extensively studied group of materials for which the global industry is looking for new applications. Issues such as bondability, durability and fire resistance still require development to improve the usability of the wood-plastic composite material. Improvement of the usability of wood-plastic composites is studied in this thesis through the effects of using selected modification technology in wood and plastic industry. The applied modification methods are surface by mechanical abrasion and plasma, chemical impregnation of wood flour, and structural modification by the co-extrusion process. The study shows that the properties of WPC can be influenced by the selected modification methods. The selected methods are also found to be able to result as improvement in the properties of the material. The may also affect other than just the targeted properties of the end-product, either in a positive or a negative manner. Therefore modification as performance improvement should be considered as a caseby- case study. Introducing WPC materials for new applications can be done by using modification technology. Structuralmodification can possibly be used to reduce material costs of the modified WPC material.

Nocturnal Transcutaneous Carbon Dioxide and Early Changes in Atherosclerosis in Pre- and Postmenopausal Women

The risk of cardiovascular diseases and sleep-disordered breathing increases after menopause. This cross-sectional study focuses on overnight transcutaneous carbon dioxide (TcCO₂) measurements and their power to predict changes in the early markers of cardiovascular and metabolic diseases. The endothelial function of the brachial artery, the intima-media thickness of the carotid artery, blood pressure, glycosylated hemoglobin A1C and plasma levels of cholesterols and triglycerides were used as markers of cardiovascular and metabolic diseases. The study subjects consisted of healthy premenopausal women of 46 years of age and postmenopausal women of 56 years of age. From wakefulness to sleep, the TcCO₂ levels increased more in postmenopausal women than in premenopausal women. In estrogen-users the increase in TcCO₂ levels was even more pronounced than in other postmenopausal women. From the dynamic behaviour of the nocturnal TcCO₂ signal, several important features were detected. These TcCO₂ features had a remarkable role in the prediction of endothelial dysfunction and thickening of the carotid wall in healthy premenopausal women. In addition, these TcCO₂ features were linked with blood pressure, lipid profile and glucose balance in postmenopausal women. The nocturnal TcCO₂ profile seems to contain significant information, which is associated with early changes in cardiovascular diseases in middle-aged women. TcCO₂ might not only measure the tissue carbon dioxide levels, but the TcCO₂ signal variation may also reflect peripheral vasodynamic events caused by increased sympathetic activity during sleep.

Molecular patterns behind immunological and metabolic alterations in lysinuric protein intolerance

Lysinuric protein intolerance (LPI) is a recessively inherited disorder characterised by reduced plasma and increased urinary levels of cationic amino acids (CAAs), protein malnutrition, growth failure and hyperlipidemia. Some patients develop severe immunological, renal and pulmonary complications. All Finnish patients share the same LPIFin mutation in the SLC7A7 gene that encodes CAA transporter y+LAT1. The aim of this study was to examine molecular factors contributing to the various symptoms, systemic metabolic and lipid profiles, and innate immune responses in LPI. The transcriptomes, metabolomes and lipidomes were analysed in whole-blood cells and plasma using RNA microarrays and gas or liquid chromatography-mass spectrometry techniques, respectively. Toll-like receptor (TLR) signalling in monocyte-derived macrophages exposed to pathogens was scrutinised using qRT-PCR and the Luminex technology. Altered levels of transcripts participating in amino acid transport, immune responses, apoptosis and pathways of hepatic and renal metabolism were identified in the LPI whole-blood cells. The patients had increased non-essential amino acid, triacylglycerol and fatty acid levels, and decreased plasma levels of phosphatidylcholines and practically all essential amino acids. In addition, elevated plasma levels of eight metabolites, long-chain triacylglycerols, two chemoattractant chemokines and nitric oxide correlated with the reduced glomerular function in the patients with kidney disease. Accordingly, it can be hypothesised that the patients have increased autophagy, inflammation, oxidative stress and apoptosis, leading to hepatic steatosis, uremic toxicity and altered intestinal microbe metabolism. Furthermore, the LPI macrophages showed disruption in the TLR2/1, TLR4 and TLR9 pathways, suggesting innate immune dysfunctions with an excessive response to bacterial infections but a deficient viral DNA response.