Surface characterization of chemically modified fiber, wood and paper

Inorganic-organic sol-gel hybrid coatings can be used for improving and modifying properties of wood-based materials. By selecting a proper precursor, wood can be made water repellent, decay-, moisture- or UV-resistant. However, to control the barrier properties of sol-gel coatings on wood substrates against moisture uptake and weathering, an understanding of the surface morphology and chemistry of the deposited sol-gel coatings on wood substrates is needed. Mechanical pulp is used in production of wood-containing printing papers. The physical and chemical fiber surface characteristics, as created in the chosen mechanical pulp manufacturing process, play a key role in controlling the properties of the end-use product. A detailed understanding of how process parameters influence fiber surfaces can help improving cost-effectiveness of pulp and paper production. The current work focuses on physico-chemical characterization of modified wood-based materials with surface sensitive analytical tools. The overall objectives were, through advanced microscopy and chemical analysis techniques, (i) to collect versatile information about the surface structures of Norway spruce thermomechanical pulp fiber walls and understand how they are influenced by the selected chemical treatments, and (ii) to clarify the effect of various sol-gel coatings on surface structural and chemical properties of wood-based substrates. A special emphasis was on understanding the effect of sol-gel coatings on the water repellency of modified wood and paper surfaces. In the first part of the work, effects of chemical treatment on micro- and nano-scale surface structure of 1st stage TMP latewood fibers from Norway spruce were investigated. The chemicals applied were buffered sodium oxalate and hydrochloric acid. The outer and the inner fiber wall layers of the untreated and chemically treated fibers were separately analyzed by light microscopy, atomic force microscopy and field-emission scanning electron microscopy. The selected characterization methods enabled the demonstration of the effect of different treatments on the fiber surface structure, both visually and quantitatively. The outer fiber wall areas appeared as intact bands surrounding the fiber and they were clearly rougher than areas of exposed inner fiber wall. The roughness of the outer fiber wall areas increased most in the sodium oxalate treatment. The results indicated formation of more surface pores on the exposed inner fiber wall areas than on the corresponding outer fiber wall areas as a result of the chemical treatments. The hydrochloric acid treatment seemed to increase the surface porosity of the inner wall areas. In the second part of the work, three silane-based sol-gel hybrid coatings were selected in order to improve moisture resistance of wood and paper substrates. The coatings differed from each other in terms of having different alkyl (CH3–, CH3-(CH2)7–) and fluorocarbon (CF3–) chains attached to the trialkoxysilane sol-gel precursor. The sol-gel coatings were deposited by a wet coating method, i.e. spraying or spreading by brush. The effect of solgel coatings on surface structural and chemical properties of wood-based substrates was studied by using advanced surface analyzing tools: atomic force microscopy, X-ray photoelectron spectroscopy and time-of-flight secondary ion spectroscopy. The results show that the applied sol-gel coatings, deposited as thin films or particulate coatings, have different effects on surface characteristics of wood and wood-based materials. The coating which has a long hydrocarbon chain (CH3-(CH2)7–) attached to the silane backbone (octyltriethoxysilane) produced the highest hydrophobicity for wood and wood-based materials.

Synthesis and Characterization of Cellulose fiber-silica nanocomposites

Cellulose fiber-silica nanocomposites with novel mechanical, chemical and thermal properties have potential to be widely applied in different area. Monodispered silica nanoparticles play an important role in enhancing hybrids properties of hardness, strength, thermal stability etc. On the other hand, cellulose is one of the world’s most abundant and renewable polymers and possesses several unique properties required in many areas and biomedicine. The aim of this master thesis is to study if silica particles from reaction of sodium silicate and sulphuric acid can be adsorbed onto cellulose fiber surfaces via in situ growth. First, nanosilica particles were synthesized. Effect of pH and silica contents were tested. In theoretical part, introduction of silica, methods of preparation of nanosilica from sodium silicate, effect factors and additives were discussed. Then, cellulose fiber-silica nanocomposites were synthesis via route from sodium silicate and route silicic acid. In the experiment of route from sodium silicate, the effects of types of sodium silicate, pH and target ratio of silica to fiber were investigated. From another aspect, the effects of types of sodium silicate, fiber concentration in mixture solution and target ratio of silica to fiber were tested in the experiment of route from silicic acid. Samples were investigated via zeta potential measurement, particle size distribution, ash content measurement and Scanning Electron Microscopy (SEM). The Results of the experiment of preparing silica sol were that the particle size of silica sol was smaller prepared in pH 11.7 than that prepared in pH 9.3. Then in the experiment of synthesis of cellulose fiber-silica nanocomposites, it was concluded that the zeta potential of all the samples were around -16 mV and the highest ash content of all the samples was only 1.4%. The results of SEM images showed only a few of silica particles could be observed on the fiber surface, which corresponded to the value of ash content measurement.

Tartrate-Resistant Acid Phosphatase 5b: a Serum Marker of Bone Resorption

Bone is a physiologically dynamic tissue being constantly regenerated throughout life as a consequence of bone turnover by bone-resorbing osteoclasts and bone-forming osteoblasts. In certain bone diseases, such as osteoporosis, the imbalance in bone turnover leads to bone loss and increased fracture risk. Measurement of bone mineral density (BMD) predicts the risk of fracture, but also biochemical markers of bone metabolism have been suggested to be suitable for prediction of fractures and monitoring the efficacy of antiresorptive treatment. Tartrate-resistant acid phosphatase 5b (TRACP 5b) is an enzyme released from osteoclasts into the circulation, from where it can be detected kinetically or immunologically. Conventional assays for serum total TRACP were spectrophotometric and suffered from interference by other acid phosphatases and non-osteoclastic TRACP 5a isoform. Our aim was to develop novel immunoassays for osteoclastic TRACP 5b. Serum TRACP 5b levels were elevated in individuals with high bone turnover, such as children, postmenopausal women, patients with osteoporosis, Paget’s disease and breast cancer patients with bone metastases. As expected, hormone replacement therapy (HRT) in postmenopausal women decreased the levels of serum TRACP 5b. Surprisingly, the highest TRACP 5b levels were observed in individuals with rare autosomal dominant osteopetrosis type II (ADO2), which is characterized by high BMD and fracture risk with simultaneously elevated levels of deficient osteoclasts. In ADO2 patients, elevated levels of serum TRACP 5b were associated with high fracture frequency. It is likely that serum TRACP 5b reflects the number of inactive osteoclasts in ADO2. Similar results supporting the hypothesis that TRACP 5b would reflect the number of osteoclasts instead of their activity were observed with cultured osteoclasts and in animal models. Novel TRACP 5b immunoassays may prove to be of value either as independent or combinatory tools with other bone metabolic markers and BMD measurements in clinical practice and bone research.

Classification of acid sulphate soils of Finland according to Soil Taxonomy and the FAO/Unesco legend

Selostus: Suomen happamien sulfaattimaiden kansainvälinen luokittelu

The biotechnology of lactic acid bacteria with emphasis on applications in food safety and human health

Selostus: Terveyttä ja ruoan turvallisuutta edistävät maitohappobakteerien biotekniset sovellukset

Contribution of modern biotechnology of lactic acid bacteria to development of health-promoting foods

Selostus: Terveysvaikutteisten elintarvikkeiden tuottamista edesauttavat maitohappobakteerien molekyyligeneettiset tutkimukset

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

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

Selostus: Kationi-anionitasapaino ja kalsiumin saanti ummessaolevien lypsylehmien säilörehuruokinnassa

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

Selostus: Kationi-anionitasapaino ja magnesiumin saanti ummessaolevien lypsylehmien säilörehuruokinnassa