Hallsta paper mill uses large amounts of water during the pulp and paper making processes. The wastewater is treated in two separate activated sludge processes referred to as BIO 1 and BIO 2. The main aim is to reduce the organic substance content, measured as COD (Chemical Oxygen Demand) before the wastewater is released into the environment. Since the effluent produced is very rich in organic substances, the addition of nitrogen (N) and phosphorus (P) are necessary to give satisfactory treatment results. Problems with sludge bulking sometimes occur which lead to increased levels of suspended matter and nutrients in the effluent. Periods of high concentration of phosphorus is also of great concern. The aim of this study is to investigate the causality behind the sludge bulking, with the help of scientific literature and analysis of previously compiled data using multivariate data analysis. COD and nutrients present in the influent will also be surveyed to identify variations in concentration caused by the paper making process. The scientific literature points toward low nitrogen and phosphorus levels as the major causes of the bulking sludge, as this leads to increased growth of filamentous bacteria to the detriment of the preferred flocculating species. A full scale experiment was conducted in an attempt to evaluate sufficient dosage levels of N and P to reduce this problem. The experiment has produced stabile results with low percentages of suspended organic matter and nutrients. Evaluation of the previously collected data using Multivariate Data Analysis did not lead to any correlation between variables being found, other than the impact of sludge concentration on COD-reduction. No relevant explanation to periods of high phosphorus levels could be found neither in the scientific literature nor in the multivariate data analysis. Bleaching of the paper pulp, with hydrogen peroxide and lye, results in a subsequent increase in COD concentration in the wastewater. The study shows an increased COD in the water approximately 12 hours after the increased dosing of these bleaching agents. Also the amounts of easily degradable COD increases following increased dosage of hydrogen peroxide and lye. The content of easily accessible phosphorus in the influent represents a minimum of 25 % and 20 % of the amount theoretically required for BIO1 and BIO2 respectively. The influent levels of nitrogen represents 33 % and 100 % for BIO1 and BIO2 respectively. From this study it has been possible to deduce that a controlled dosage of nutrients in relation to the incoming level of COD, is of great importance to the efficient treatment of COD rich effluent in the systems under investigation at Hallsta Papermill. / Vid Hallsta Pappersbruk används stora mängder vatten vid tillverkningen av massa och papper. Det förorenade processvattnet renas i två separata anläggningar, BIO1 och BIO2, båda med biologisk rening av typen aktivt slam. Avloppsvattnets höga halter av kolföreningar, vilka analyseras som COD (Chemical Oxygen Demand), kräver extra tillsats av kväve och fosfor för att erhålla tillfredsställande reningsresultat. I den biologiska reningen uppstår periodvis problem med slamsvällning, något som resulterar i höga utsläpp av suspenderat material och organiskt bundna näringsämnen. Även perioder med höga fosforutsläpp förekommer. Syftet med examensarbetet är att genom litteraturstudier och analys av historiska data, med hjälp av multivariat dataanalys, utreda orsakerna till problemen. Även en kartläggning av variationerna i inkommande avloppsvatten med avseende på COD och lättillgängliga näringsämnen genomförs. Utifrån information från litteraturen tyder problemen med slamsvällning ofta på bristande tillgång på kväve och fosfor vilket bland annat kan resultera i kraftig tillväxt av filamentösa bakterier. För att komma till rätta med problemen startades ett styrt försök med beräknade optimala doseringskvoter. Försöket resulterade i stabil drift för båda anläggningarna med låga utsläppsnivåer av både suspenderat material och näringsämnen. Resultatet från utvärderingen av driftsdata med multivariat analys visar att slamhalten har betydelse för COD-reduktionen i BIO1. Någon förklaring till problemen med höga fosforutsläpp har inte framkommit vare sig ur litteraturstudie eller multivariat dataanalys. Vid alkalisk oxiderande blekning av termomekanisk pappersmassa ökar den totala COD-koncentrationen i avloppsvattnet i samband med höjd dosering av blekkemikalier. Studien visar att en ökad COD-koncentration kan observeras i vattnet in till BIO1 ca 12 timmar efter förhöjd dosering av blekkemikalier. Samtidigt ökar andelen lättnedbrytbart COD till följd av ökad blekningsgrad. Kartläggningen av inkommande vatten visar att mängden lättillgängligt kväve i avloppsvattnet in till biologierna motsvarar ca 33 % och 100 % av det teoretiskt beräknade behovet för BIO1 respektive BIO2. För fosfor uppgår motsvarande till minst 25 % respektive 20 % för BIO1 och BIO2. Under examensarbetets gång har det kunnat konstateras att dosering av närsalter i förhållande till inkommande mängd COD är av stor vikt för en väl fungerande rening av det COD-rika avloppsvattnet vid Hallsta Pappersbruk.

Two problems in the study of elastic filaments are considered.First, a reliable numerical algorithm is developed that candetermine the shape of a static elastic rod under a variety ofconditions. In this algorithm the governing equations are writtenentirely in terms of local coordinates and are discretized usingfinite differences. The algorithm has two significant advantages:firstly, it can be implemented for a wide variety of the boundaryconditions and, secondly, it enables the user to work with generalconstitutive relationships with only minor changes to thealgorithm. In the second problem a model is presented describingthe dynamics of an elastic tube conveying a fluid. First weanalyze instabilities that are present in a straight rod or tubeunder tension subject to increasing twist in the absence of afluid. As the twist is increased beyond a critical value, thefilament undergoes a twist-to-writhe bifurcation. A multiplescales expansion is used to derive nonlinear amplitude equationsto examine the dynamics of the elastic rod beyond the bifurcationthreshold. This problem is then reinvestigated for an elastic tubeconveying a fluid to study the effect of fluid flow on thetwist-to-writhe instability. A linear stability analysisdemonstrates that for an infinite rod the twist-to-writhethreshold is lowered by the presence of a fluid flow. Amplitudeequations are then derived from which the delay of bifurcation dueto finite tube length is determined. It is shown that the delayedbifurcation threshold depends delicately on the length of the tubeand that it can be either raised or lowered relative to thefluid-free case. The amplitude equations derived for the case of aconstant average fluid flux are compared to the case where theflux depends on the curvature. In this latter case it is shownthat inclusion of curvature results in small changes in some ofthe coefficients in the amplitude equations and has only a smalleffect on the post-bifurcation dynamics.

No description available.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

The embryonic mouse inner ear was used as a model with which to study ototoxicity and tissue interactions. The inner ear anlage can be explanted and cultured in vitro from about the 12th gestational day (gd), and will differentiate parallel with the inner ear developing in vivo until a time corresponding to birth (21st gd). During this period the ovoid sac develops into the labyrinth. In the present thesis work, otic anlagen from gd 12, 13, 13.5, 15 and 16 were used. As a rule the explants were kept in culture until a time point equivalent to the 21st gd. Analyses using freeze-fracture technique and transmission electron microscopy showed that in cultured 13th gd otocysts the development of junctional complexes followed the same principal pattern as in vivo. Tight junctions develop into many strands lying parallel to the apical surface of all epithelial cells. Uncoupling of the hair cells occurs with loss of gap junctions. Some tight junctions had an aberrant appearence, with in part very thick strands and strands running at right angles to the apical surface. All aminoglycosides are potentially ototoxic. In the inner ear, outer hair cells of the organ of Corti and vestibular type I hair cells are affected by these antibiotics. The access route to the hair cells and the sites and mechanisms of action of aminoglycosides are not precisely defined. The uptake of tritiated tobramycin in 16th gd inner ears was studied. An initial rapid uptake of the drug, within 10 min, was followed by a slower accumulation, reaching a steady state after 60 min. Most of the tobramycin was bound reversibly, at least after a short period of incubation (2 h). The irreversibly bound fraction was of the same magnitude as the uptake within 10 min. Uptake took place against a concentration gradient. The otocyst can differentiate even without the statoacoustic ganglion. The interaction of the sensory epithelium with the ganglion was investigated by explanting the statoacoustic ganglion without target tissue. Twenty-five percent of the ganglions survived and had outgrowth of neurites but there was no differentiation into either the cochlear or vestibular type of neuron cells. Exposure of cultured otocysts (13 or 13.5 gd) to l-azetidine-2-carboxylic acid, a 1-proline analog that disrupts formation of collagen, resulted in retarded morphogenesis of the labyrinth and a dose- dependent derangement of the basal lamina. The expression of intermediate filaments (IFs) was analysed using monoclonal antibodies. The same IF pattem was found in cultured inner ears as in vivo. Explants were taken on 13th, 15th or 16th gd. Exposure to gentamicin, ethacrynic acid or cisplatin did not alter the IF composition. Cytokeratins (CKs) 8 and 18 were identified in all inner ear epithelia. In addition CKs 7 and 19 were visualized in the epithelia involved in maintaining endolymph homeostasis. The ganglion cells showed coexpression of CK, vimentin and neurofilaments. The elemental composition of the endolymph compartment of 16th gd inner ears cultured for 5 days was studied using energy-dispersive X-ray microanalysis. Na to K ratios characteristic of endolymph were found. / <p>S. 1-34: sammanfattning, s. 37-88: Härtill 6 uppsatser</p> / digitalisering@umu

In 1995 Braun and co-workers reported the observation of self-channeling of femtosecond laser pulses over 20 m in air. This first observation of femtosecond filament triggered a series of studies, which discovered an exciting physics beyond the interaction of ultrashort laser pulses with transparent dielectric media. This dissertation aims at comprehensive study of transient spatiotemporal phenomena (space-time transformations, pulse splitting and compression, filament propagation dynamics, supercontinuum generation and multiple filamentation) that take place during self-focusing of intense femtosecond laser pulses in various self-action regimes in transparent dielectric media with instantaneous Kerr nonlinearity. Various nonlinear optics diagnostic methods (three dimensional mapping, auto- and cross-correlation measurements, frequency resolved optical gating measurements), spatially resolved frequency spectra measurements, statistical analysis of spectral intensities and energies, numerical simulations were employed. The dissertation addresses important issues regarding complete physical understanding of the evolution cycle of femtosecond filaments in normally dispersive media, physical nature of spatiotemporal light bullets generated by filamentation in the anomalous group velocity regime, detailed statistical aspects of supercontinuum generation, and spatiotemporal characterization of multiple filaments. Analysed factors are useful for practical applications when... [to full text] / Ultratrumpiesiems šviesos impulsams sklindant skaidriose terpėse dėl jų saviveikos gali formuotis ypatingi šviesos dariniai – šviesos gijos, kurios pirmą kartą stebėtos 1995 m. Braun ir kt. Pirmuosius šviesos gijų stebėjimus sekė eilė tyrimų, kurie atskleidė įdomius femtosekundinių lazerinių impulsų saviveikos reiškinius, kartais apimančius platesnes netiesinės optikos tyrimų sritis. Šios disertacijos tikslas – išsamiai ištirti dinaminius erdvėlaikinius reiškinius (šviesos gijų sklidimą, erdvėlaikines transformacijas, impulsų skilimą ir spūdą, superkontinuumo generaciją ir daugelio šviesos gijų atsiradimą) įvairiuose intensyvių femtosekundinių lazerio impulsų saviveikos režimuose skaidriose dielektrinėse terpėse su momentiniu Kero netiesiškumu. Tyrimams naudoti įvairūs netiesinės optikos metodai (trimatė lazerinė tomografija, auto- ir kryžminės koreliacijos matavimai, dažninės skyros optinės sklendės autokoreliaciniai matavimai), erdvinės-dažninės skyros spektrų matavimas, statistinė spektrinių, energijos matavimų analizė, skaitmeninis modeliavimas. Atliktų tyrimų visuma išplečia esamas žinias apie femtosekundinių šviesos impulsų saviveiką ir netiesinių optinių sistemų dinamiką normalios ir anomalios grupinių greičių dispersijos atvejais, vedančią prie nestabilumo ir ekstremalių optinių įvykių žadinimo. Kita vertus, ištirti veiksniai naudingi praktiniuose taikymuose, kai siekiama formuoti tvarkias erdvines-laikines struktūras, žadinti ekstremalias optines bangas arba... [toliau žr. visą tekstą]

Ultratrumpiesiems šviesos impulsams sklindant skaidriose terpėse dėl jų saviveikos gali formuotis ypatingi šviesos dariniai – šviesos gijos, kurios pirmą kartą stebėtos 1995 m. Braun ir kt. Pirmuosius šviesos gijų stebėjimus sekė eilė tyrimų, kurie atskleidė įdomius femtosekundinių lazerinių impulsų saviveikos reiškinius, kartais apimančius platesnes netiesinės optikos tyrimų sritis. Šios disertacijos tikslas – išsamiai ištirti dinaminius erdvėlaikinius reiškinius (šviesos gijų sklidimą, erdvėlaikines transformacijas, impulsų skilimą ir spūdą, superkontinuumo generaciją ir daugelio šviesos gijų atsiradimą) įvairiuose intensyvių femtosekundinių lazerio impulsų saviveikos režimuose skaidriose dielektrinėse terpėse su momentiniu Kero netiesiškumu. Tyrimams naudoti įvairūs netiesinės optikos metodai (trimatė lazerinė tomografija, auto- ir kryžminės koreliacijos matavimai, dažninės skyros optinės sklendės autokoreliaciniai matavimai), erdvinės-dažninės skyros spektrų matavimas, statistinė spektrinių, energijos matavimų analizė, skaitmeninis modeliavimas. Atliktų tyrimų visuma išplečia esamas žinias apie femtosekundinių šviesos impulsų saviveiką ir netiesinių optinių sistemų dinamiką normalios ir anomalios grupinių greičių dispersijos atvejais, vedančią prie nestabilumo ir ekstremalių optinių įvykių žadinimo. Kita vertus, ištirti veiksniai naudingi praktiniuose taikymuose, kai siekiama formuoti tvarkias erdvines-laikines struktūras, žadinti ekstremalias optines bangas arba... [toliau žr. visą tekstą] / In 1995 Braun and co-workers reported the observation of self-channeling of femtosecond laser pulses over 20 m in air. This first observation of femtosecond filament triggered a series of studies, which discovered an exciting physics beyond the interaction of ultrashort laser pulses with transparent dielectric media. This dissertation aims at comprehensive study of transient spatiotemporal phenomena (space-time transformations, pulse splitting and compression, filament propagation dynamics, supercontinuum generation and multiple filamentation) that take place during self-focusing of intense femtosecond laser pulses in various self-action regimes in transparent dielectric media with instantaneous Kerr nonlinearity. Various nonlinear optics diagnostic methods (three dimensional mapping, auto- and cross-correlation measurements, frequency resolved optical gating measurements), spatially resolved frequency spectra measurements, statistical analysis of spectral intensities and energies, numerical simulations were employed. The dissertation addresses important issues regarding complete physical understanding of the evolution cycle of femtosecond filaments in normally dispersive media, physical nature of spatiotemporal light bullets generated by filamentation in the anomalous group velocity regime, detailed statistical aspects of supercontinuum generation, and spatiotemporal characterization of multiple filaments. Analysed factors are useful for practical applications when... [to full text]

No description available.

Thèse (Ph.D.)--Université Laval, 2003. / Bibliogr.: f. [247]- 269. Publié aussi en version électronique.

Thesis (Ph. D. in Physics)--Vanderbilt University, May 2006. / Title from title screen. Includes bibliographical references.