Effect of fertilization on soil phosphorus in a long-term field experiment in southern Finland

Selostus: Maan fosforitilan muutos pitkäaikaisessa kenttäkokeessa hietamaalla

The effect of genotype on anther culture response of cultivated and wild oats

Selostus: Genotyypin vaikutus kauran, kuorettoman kauran ja villikauran ponsiviljelyvasteeseen

Effect of fertilization on flowering and seed crop in Scots pine seed orchards

Summary

Effect of pruning on tree growth, yield, and wood properties of Tectona grandis plantations in Costa Rica

Abstract

Effect of thinning on stem form and wood characteristics of teak (Tectona grandis) in a humid tropical site in Costa Rica

Abstract

Modelling the effect of temperature on height increment of Scots pine at high latitudes

Abstract

Effect of liming on yield and quality of pepperment and Sachalin mint in fine sand soil of Northern Finland

Selostus: Kalkituksen vaikutus piparmintun ja Sachalinin mintun satoon Pohjois-Suomessa

Effect of vegetation on snow cover at the northern timberline : a case study in Finnish Lapland

[Abstract]

Effect of antifoams on oxygen mass transfer in pulp and paper mill effluents

Vaahdonestoaineiden haitallinen vaikutus hapen liukenemisnopeuteen biologisen puhdistamon jätevesissä on yleisesti tunnettua. Aineiden eri vaikutusmekanismien takia on silti vaikea etukäteen arvioida, miten ja kuinka paljon aineensiirto muuttuu. Työn tavoitteena oli saada tietoa vaahdonestoaineiden ja muiden pinta-aktiivisten aineiden vaikutuksesta kuplakokoon, kaasun tilavuusosuuteen ja kaasu-neste aineensiirtoon. Työn teoriaosassa on kuvailtu vaahdon muodostumiseen vaikuttavia tekijöitä sekä eri vaahdonestoaineiden vaikutusmekanismeja sellu- ja paperitehtaan jätevedessä. Edelleen on esitetty useita hapen siirtoa estäviä ja parantavia aineita. Työn kokeellisessa osassa tutkittiin kahdenkymmenenviiden eri pinta-aktiivisen aineen vaikutusta hapen liukenemisnopeuteen yksivaiheisessa kuplakolonnissa. Kokeet tehtiin kahdella pitoisuudella, kahdella eri kaasunjakolaitteella ja kolmella eri kaasun tyhjäputkinopeudella. Aineensiirtokokeiden rinnalla tutkittiin jätevesien laatu- ja fysikaalisiaominaisuuksia, niiden vaikutusta hapen liukenemisnopeuteen sekä testattavien koeaineiden vaikutusta fysikaalisin ominaisuuksiin. Kokeet osoittavat että pinta-aktiivisten aineiden vaikutus hapen aineensiirtoon vaihtelee riippuen kaasunjakolaitteesta ja aineen pitoisuuksista. Testatuista vaahdonestonaineista pienin negatiivinen vaikutus oli aineella AT 35 ja positiivinen vaikutustodettiin olevan vaahdonestoaineiden komponenteilla: P2, S1, F4 ja T9.

Poisoning effect of s on pd surfaces

In this study we observe the poisoning effect of S to the adsorption and dissociation of 02 molecule on Pd surfaces. To perform this study we used Viennaab initio Simulation Package (VASP) and Spanish Initiative for Electronic structure with thousands of Atoms (SIESTA) ab initio softwares. To describe all Pd surfaces we selected the (100), and (211) surfaces, because we need very reactive and simple surfaces. Before studying the poison¬ing effect of S we had to study the dissociation of 02 on the surfaces. We discovered that on the (100) surface the hollow site is the most reactive site, but at room temperature the steric hinderace effect occurs very easily. If the molecule has enough vibrational energyit will dissociate. On the (211) surface the (100) micro facet's hollow site is the most reactive site and the molecule dissociates in the site without any barrier, and the molecule drifts from the terrace to this site. An S atom sticks on the Pd (100) surface in the hollow site. It affects the d-band density of states of the nearests Pd atoms; It moves the center of the d-band downin energy, when the bond between the Pd atom and the 0 atom is more antibonding. In the hollow site the S atom also blocks the dissociation site of the molecule. On the Pd(211) surface the energetically favourable site of the S atom is the(100) microfacet's hollow site. There it blocks the most reactive site, but its effect to the Pd atoms next to it is not significant.

Effect of hydrodynamics on modelling, monitoring and control of crystallization

Crystallization is a purification method used to obtain crystalline product of a certain crystal size. It is one of the oldest industrial unit processes and commonly used in modern industry due to its good purification capability from rather impure solutions with reasonably low energy consumption. However, the process is extremely challenging to model and control because it involves inhomogeneous mixing and many simultaneous phenomena such as nucleation, crystal growth and agglomeration. All these phenomena are dependent on supersaturation, i.e. the difference between actual liquid phase concentration and solubility. Homogeneous mass and heat transfer in the crystallizer would greatly simplify modelling and control of crystallization processes, such conditions are, however, not the reality, especially in industrial scale processes. Consequently, the hydrodynamics of crystallizers, i.e. the combination of mixing, feed and product removal flows, and recycling of the suspension, needs to be thoroughly investigated. Understanding of hydrodynamics is important in crystallization, especially inlargerscale equipment where uniform flow conditions are difficult to attain. It is also important to understand different size scales of mixing; micro-, meso- and macromixing. Fast processes, like nucleation and chemical reactions, are typically highly dependent on micro- and mesomixing but macromixing, which equalizes the concentrations of all the species within the entire crystallizer, cannot be disregarded. This study investigates the influence of hydrodynamics on crystallization processes. Modelling of crystallizers with the mixed suspension mixed product removal (MSMPR) theory (ideal mixing), computational fluid dynamics (CFD), and a compartmental multiblock model is compared. The importance of proper verification of CFD and multiblock models is demonstrated. In addition, the influence of different hydrodynamic conditions on reactive crystallization process control is studied. Finally, the effect of extreme local supersaturation is studied using power ultrasound to initiate nucleation. The present work shows that mixing and chemical feeding conditions clearly affect induction time and cluster formation, nucleation, growth kinetics, and agglomeration. Consequently, the properties of crystalline end products, e.g. crystal size and crystal habit, can be influenced by management of mixing and feeding conditions. Impurities may have varying impacts on crystallization processes. As an example, manganese ions were shown to replace magnesium ions in the crystal lattice of magnesium sulphate heptahydrate, increasing the crystal growth rate significantly, whereas sodium ions showed no interaction at all. Modelling of continuous crystallization based on MSMPR theory showed that the model is feasible in a small laboratoryscale crystallizer, whereas in larger pilot- and industrial-scale crystallizers hydrodynamic effects should be taken into account. For that reason, CFD and multiblock modelling are shown to be effective tools for modelling crystallization with inhomogeneous mixing. The present work shows also that selection of the measurement point, or points in the case of multiprobe systems, is crucial when process analytical technology (PAT) is used to control larger scale crystallization. The thesis concludes by describing how control of local supersaturation by highly localized ultrasound was successfully applied to induce nucleation and to control polymorphism in reactive crystallization of L-glutamic acid.