Filmipäällystimen nippitapahtuman vaikutus päällystyskoneen ajettavuuteen

Työn tavoitteena oli syventyä filmipäällystimen nippitapahtumaan ja siellä tapahtuviin ilmiöihin. Tämän lisäksi selvitettiin esipäällystysparametrien ja pohjapaperin merkitys filmipäällystimen ajettavuudelle. Erityisesti pyrittiin selvittämään päällystemäärän ja applikointitelojen momenttieron vaikutus ajettavuuteen sekä kiihdytysvaiheessa ilmenevien ajettavuusongelmien syntymekanismit. Työn kokeellinen osa jakaantui kahteen osaan. Ensimmäisessä osassa pyritään löytämään lisäymmärrystä nippitapahtuman ilmiöille joita sitten hyödynnetään toisen osan koeajoissa. Staattisilla kuormituskokeilla tutkittiin telapinnan kokoonpuristumista ja suurnopeus-kamerakuvauksilla nipin geometriaa päällystyskoneen ajon aikana. Applikointitelojen momenttierokoeajoilla pyrittiin selvittämään paperiradan mahdollista luistoa nipissä. MCA-kosteuspitoisuusanalysaattorilla mitattiin nippitapahtuman muutosten vaikutusta filmipäällystimen paluufilmin ominaisuuksiin. Muuttelemalla päällystemäärää ja – jakaumaa sekä applikointitelojen momenttieroa selvitettiin esipäällystysparametrien vaikutus filmipäällystimen ajettavuuteen. Muokkaamalla pohjapaperin absorptiokykyä sekä pastan vedenpidätyskykyä tutkittiin nestepenetraation vaikutusta ajettavuuteen. Telapinnan kokoonpuristuman havaittiin olevan pieni eikä ajon aikana nipin geometriassa havaittu muutoksia. Paperiradan todettiin luistavan nipissä, mutta luistoilmiö oli huomattavasti pienempi mitä nopeuserolukemista voidaan päätellä. Kiihdytysvaiheessa havaittiin selviä muutoksia paluufilmissä, mutta ajon aikana paluufilmi pysyi lähes vakiona. Päällystemäärän todettiin olevan suurin yksittäinen tekijä filmipäällystimen ajettavuudessa ja siihen tulee kiinnittää erityistä huomiota filmipäällystimen kiihdytysvaiheessa. Aukirullauksen levitystelan vaihdon myötä todettiin pohjapaperiin kohdistuvilla kuormituksilla olevan myös suuri merkitys filmipäällystimen ajettavuudelle.

Development of a Filter Aid Proportioning, Mixing, and Feeding System for a Polishing Filter

The purpose of this work was to study the characteristics of the most commonly used filter aid materials and their influences on the design of proportioning, mixing, and feeding system for polishing filter family. Based on the literature survey and hands-on experience a system was designed with defined equipment and capital and operating costs. The system was designed to serve precoating and bodyfeeding applications and is easily extended to be used in multiple filter processes. Also a test procedure was carried out where influences of flux and filter cloths to accumulated cake were studied. Filter aid is needed in challenging conditions to improve filtration efficiency and cleaning, and thus extend the operating life of the filter media. Filter aid preparation and feeding system was designed for the use of two different filter aids; precoat and bodyfeed. Precoating is used before the filtration step initiates. If the solids in the filterable solution have a tendency to clog the filter bag easily, precoat is used on the filter bag to obtain better filtration efficiency and quality. Diatomite or perlite is usually used as a precoating substance. The intention is to create a uniform cake to the overall surface of the filter cloth, with predetermined thickness, 2 – 5 mm. This ensures that the clogging of the filter cloth is reduced and the filtration efficiency is increased. Bodyfeed is used if the solids in the filterable solution have a tendency to form a sticky impermeable filter cake. The cake properties are enhanced by maintaining the permeability of the accumulating cake by using the filter aid substance as bodyfeed during the filtration process.

Surface-enhanced Raman scattering study of alizarin red S

This paper presents the application of surface-enhanced resonance Raman spectroscopy (SERRS) for the structural study of alizarin red S (ARS) and the nature of its interaction with silver nanoparticles. SERRS data for ARS over nanostructured silver electrodes suggest a surface-induced reaction of the adsorbed dye and the formation of an ion stabilized by the dye and alkali ions adsorbed at the metal surface. We found that precoating the SERS active substrate with 1-propanethiol inhibits the surface-induced modification of ARS. In addition to preventing structural modifications of ARS, the coating also concentrates the hydrophobic dye close enough to the SERS active interface enabling the observation of excellent Raman spectra of ARS in aqueous environment at ppm levels. The influence of resonance Raman effect and of the pH on the SERS spectra of ARS was also investigated. (C) 2010 Elsevier B.V. All rights reserved.

Influence of the type of phospholipid head and of the conformation of the polyelectrolyte on the growth of calcium carbonate thin films on LB/LbL matrices

Calcium carbonate is one of the most important biominerals, and it is the main constituent of pearls, seashells, and teeth. The in vitro crystallization of calcium carbonate using different organic matrices as templates has been reported. In this work, the growth of calcium carbonate thin films on special organic matrices consisting of layer-by-layer (LbL) polyelectrolyte films deposited on a pre-formed phospholipid Langmuir-Blodgett (LB) film has been studied. Two types of randomly coiled polyelectrolytes have been used: lambda-carrageenan and poly(acrylic acid). A precoating comprised of LB films has been prepared by employing a negatively charged phospholipid, the sodium salt of dimyristoilphosphatidyl acid (DMPA), or a zwitterionic phospholipid, namely dimyristoilphosphatidylethanolamine (DMPE). This approach resulted in the formation of particulate calcium carbonate continuous films with different morphologies, particle sizes, and roughness, as revealed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The crystalline structure of the calcium carbonate particles was analyzed by Raman spectroscopy. The randomly coiled conformation of the polyelectrolytes seems to be the main reason for the formation of continuous films rather than CaCO3 isolated crystals. (C) 2012 Elsevier B.V. All rights reserved.

Construction of skeletal myoblast-based polyurethane scaffolds for myocardial repair

Intramyocardial transplantation of skeletal myoblasts augments postinfarction cardiac function. However, poor survival of injected cells limits this therapy. It is hypothesized that implantation of myoblast-based scaffolds would result in greater cell survival. Rat skeletal myoblasts were seeded on highly porous polyurethane (PU) scaffolds (7.5 x 7.5 x 2.0 mm). The effect of several scaffold pretreatments, initial cell densities, and culture periods was tested by DNA-based cell count and viability assessment. Seeded PU scaffolds were implanted on infarcted hearts and immunohistology was performed 4 weeks later. Precoating with laminin allowed the most favorable cell attachment. An initial inoculation with 5 x 10(6) cells followed by a 15-day culture period resulted in optimal myoblast proliferation. Four weeks after their implantation in rats, numerous myoblasts were found throughout the seeded patches although no sign of differentiation could be observed. This myoblast seeding technique on PU allows transfer of a large number of living myoblasts to a damaged myocardium.

Roles of Alix in regulating cell morphology

Mammalian Alix (ALG2-interacting protein X&barbelow;) is a conserved adaptor protein that is involved in endosomal trafficking, apoptosis and growth factor receptor turnover. Accumulating evidence also indicates that Alix plays roles in promoting/maintaining spread and aligned fibroblast morphology in monolayer culture. Since cell morphology is determined by the structure and dynamics of an integrin-mediated transmembrane protein network that links extracellular matrix to intracellular cytoskeleton, we hypothesized that Alix plays direct or indirect roles in regulating certain components or steps in this transmembrane protein network. To test this hypothesis, we first examined the subcellular localization of Alix and discovered that, as a predominantly cytoplasmic protein, Alix is also present on the substratum/cell surface and in the conditioned medium of fibroblast cultures. Further, precoating of culture surfaces with recombinant Alix promotes spreading and fibronectin assembly to NIH/3T3 cells, and siRNA-mediated Alix knockdown in W138 cells has the opposite effects. These findings indicate the extracellular functions of Alix in regulating cell spreading and extracellular matrix assembly. In a separate study, we analyzed Alix immunocomplexes from normal fibroblast W138 cells by mass spectrometry and identified actin as a major partner protein of Alix. Follow-up studies demonstrated that Alix preferentially binds filamentous actin (F-actin) in vitro and is required for maintaining normal F-actin content and proper actin cytoskeleton assembly in W138 cells. These findings establish direct and essential roles of Alix in regulating actin cytoskeleton. Finally, we investigated the effects of Alix knockdown on the activation and subcellular localization of FAK and Pyk2, the focal adhesion kinases required for cell spreading/migration by promoting turnover of integrin-mediated cell adhesions. We discovered that Alix knockdown inhibits FAK and Pyk2 localizations to focal adhesions or plasma membrane, in association with characteristics of reduced turnover of focal adhesions. These findings reveal a positive role of Alix in focal adhesion turnover. Based on these results, we conclude that Alix targets both intracellularly and extracellularly components to regulate extracellular matrix remodeling, actin cytoskeleton assembly and focal adhesion turnover. A combination of these three functions of Alix explains its crucial role in regulating spread and aligned fibroblast morphology. ^