Monitoring of mechanical sugarcane harvesting through control charts

ABSTRACT Statistical process control in mechanized farming is a new way to assess operation quality. In this sense, we aimed to compare three statistical process control tools applied to losses in sugarcane mechanical harvesting to determine the best control chart template for this quality indicator. Losses were daily monitored in farms located within Triângulo Mineiro region, in Minas Gerais state, Brazil. They were carried over a period of 70 days in the 2014 harvest. At the end of the evaluation period, 194 samples were collected in total for each type of loss. The control charts used were individual values chart, moving average and exponentially weighted moving average. The quality indicators assessed during sugarcane harvest were the following loss types: full grinding wheel, stumps, fixed piece, whole cane, chips, loose piece and total losses. The control chart of individual values is the best option for monitoring losses in sugarcane mechanical harvesting, as it is of easier result interpretation, in comparison to the others.

Autokaupan automyynnin volyymiasiakkaiden asiakaskannattavuus

Autoalalla automyynnin transaktiokustannukset ovat merkittävä osa myyntikustannuksista. Yritykset pyrkivät alentamaan näitä kustannuksia hakemalla lisää volyymia ja keskittymällä voimakkaammin volyymikauppoihin. Tämän tutkimuksen tarkoituksena on löytää keinoja, joilla autokaupan volyymimyynnin kannattavuutta voidaan parantaa. Tutkimuksen teoreettisessa viitekehyksessä esitettiin teoriamalleja, joita hyödyntämällä autokaupan kovassa kilpailutilanteessa yritykset voisivat menestyä paremmin. Tutkimusmetodina käytettiin ei-kokeellista tutkimusasetelmaa, jossa tieto kerättiin strukturoiduilla kysymyksillä. Tutkimusaineistoksi saatiin kohdeyrityksessä ja joukosta kilpailevien yritysten henkilöiltä haastattelemalla hankittua tietoa. Johtopäätöksenä voidaan todeta, että autokaupassa liikkeenjohdon teoriat ja käytäntö seurailevat toisiaan osin hyvinkin paljon, vaikka tiettyjä ristiriitoja on havaittavissa. Yritysten tietojärjestelmistä saatavan tiedon laadun parantamisella, sovittujen toimintaprosessien noudattamisella ja olemassa olevia toimintatapoja kyseenalaistamalla volyymikaupan tuottavuutta pystytään jo nyt kohentamaan.

Nikkelin, koboltin, lyijyn ja sinkin selektiivinen erottaminen ioninleimaustekniikalla syntetisoiduilla kelatoivilla erotusmateriaaleilla

Kelatoivat erotusmateriaalit ovat osoittautuneet lupaaviksi haitallisten metallien erottamiseksi vedestä. Puhdistettava vesiliuos sisältää vain harvoin pelkästään erotettavaksi tarkoitettuja metallikationeja, sillä useimmiten mukana on erotusmateriaalien tehokkuutta heikentäviä kationeja. Parantamalla erotusmateriaalin selektiivisyyttä voitaisiin häiritsevien ionien vaikutusta vähentää selvästi. Kandidaatintyön tavoitteena oli tutkia ioninleimaustekniikan avulla syntetisoitujen kelatoivien erotusmateriaalien selektiivisyyttä nikkelille, koboltille, lyijylle ja sinkille. Käyttämällä esimerkiksi nikkelitemplaattia materiaalin synteesivaiheessa materiaalin nikkeliselektiivisyys kasvaa verrattuna perinteiseen synteesitekniikkaan. Tässä työssä tutkittiin erotusmateriaaleja, joissa oli käytetty nikkeli- tai lyijytemplaattia, vertaamalla niitä ilman templaattia syntetisoituihin materiaaleihin. Lisäksi erotustehokkuutta verrattiin kaupalliseen erotusmateriaaliin häiritsevien magnesium- ja kalsiumionien tapauksessa. Lyijyn havaittiin sitoutuvan tehokkaimmin kaikkiin syntetisoituihin materiaaleihin riippumatta nikkelitemplaatin käyttämisestä. Kinetiikkakokeet osoittivat lyijyn sitoutumisnopeudenkin olevan vertailtavista metalleista suurin. Kaikki kokeet suoritettiin huoneenlämpötilassa liuoksen pH-arvon ollessa 7,5. Nikkelitemplaatin käyttö lisäsi materiaalin selektiivisyyttä nikkelille verrattuna templaatittomaan muuten identtiseen materiaaliin. Kuitenkin materiaalien lyijyselektiivisyys oli huomattavasti nikkeliselektiivisyyttä suurempi. Lyijytemplaatin käyttö ei lisännyt lyijyselektiivisyyttä, mutta materiaalin nikkeliselektiivisyys parantui. Materiaaliin sitoutuneet nikkeli-, koboltti- ja sinkkipitoisuudet jäivät huomattavasti vähäisemmiksi verrattuna kaupalliseen materiaaliin. Magnesiumin ja kalsiumin tarttumista syntetisoituihin materiaaleihin tutkittiin myös ja tulosten mukaan IIPD2:een ja IIPD2-Methoxiin sitoutui erittäin vähän magnesiumia ja kalsiumia verrattuna kaupalliseen materiaaliin, jonka kalsiumkapasiteetti oli erityisen suuri. Kyseiset materiaalit soveltuvat tulosten perusteella myös häiritseviä ioneja sisältävien liuosten puhdistamiseen. Näin ollen valittujen kahden materiaalin jatkotutkimuksella olisi mahdollista parantaa nikkelikapasiteettia ja -selektiivisyyttä.

Nikkelille selektiivisen kelatoivan adsorbenttimateriaalin valmistus ja tutkiminen

Metallien laajamittaisen ja runsaan käytön vuoksi nykyään on keskityttävä aikaisempaa tarkemmin metallipäästöjen estämiseen ja puhdistamiseen. Metallien puhdistamiseen jätevesistä voidaan käyttää erilaisia yksikköoperaatiomenetelmiä, mutta selektiivisempään erotukseen päästään ioninvaihto- ja adsorbenttimateriaaleilla. Työn tarkoitusena on valmistaa ja tutkia nikkeliselektiivisiä adsorbenttimateriaaleja. Lisäksi tutkimuskohteena on nikkelin ja 1,10-fenantroliinin välisen kompleksin muodostuminen eri pH-arvoilla. Selektiivisten adsorbenttimateriaalien valmistaminen onnistuu liittämällä kiinteään kantajaan ligandi. Tämän työn tapauksessa nikkelitemplaatin liittäminen kiinteään kantajaan funktionalisointivaiheessa muodostaa adsorbenttiin nikkelille spesifisen kohdan. Käytännössä spesifisyyden syntyminen ei ole itsestäänselvyys, vaan se riippuu paljon funktionalisointitavasta. Tässä työssä funktionalisointitapana olivat fysikaalinen adsorptio ja impregnointi. Nikkelin ja 1,10-fenantroliinin välisen kompleksin muodostumista tutkittiin eri pH-arvojen lisäksi neljällä eri happokonsentraatiolla. Tuloksia verrattiin sellaisen liuoksen spektriin, missä oli pelkkää nikkeliä. Tuloksista havaittiin, että komplekseja muodostuu käytännössä samalla tavalla pH:n ollessa 1–6. Vasta 5 M HNO3 alkoi heikentää kompleksien muodostumista, ja 10 M HNO3 esti kompleksien muodostumisen täysin. Adsorbenttimateriaaleja valmistettiin useita erilaisia, joihin osaan liitettiin nikkelitemplaatti ja osa jätettiin ilman templaattia. Työssä keskityttiin tutkimaan erityisesti kolmea silikasta valmistettua materiaalia, joissa vain kahdessa oli nikkelitemplaatti. Nikkelitemplaattien olemassaololla ei havaittu olevan juurikaan merkitystä nikkelin erottamiseen vesiliuoksista. Materiaaleille tehdyt regenerointikokeet osoittivat, että materiaalien toiminta ja kapasiteetti eivät olleet toivotulla tasolla.

Prediction of 3D structure and ligand-binding properties : ABC transporters and flavodiiron proteins from Synechocystis sp. strain PCC 6803

Cyanobacteria are unicellular, non-nitrogen-fixing prokaryotes, which perform photosynthesis similarly as higher plants. The cyanobacterium Synechocystis sp. strain PCC 6803 is used as a model organism in photosynthesis research. My research described herein aims at understanding the function of the photosynthetic machinery and how it responds to changes in the environment. Detailed knowledge of the regulation of photosynthesis in cyanobacteria can be utilized for biotechnological purposes, for example in the harnessing of solar energy for biofuel production. In photosynthesis, iron participates in electron transfer. Here, we focused on iron transport in Synechocystis sp. strain PCC 6803 and particularly on the environmental regulation of the genes encoding the FutA2BC ferric iron transporter, which belongs to the ABC transporter family. A homology model built for the ATP-binding subunit FutC indicates that it has a functional ATPbinding site as well as conserved interactions with the channel-forming subunit FutB in the transporter complex. Polyamines are important for the cell proliferation, differentiation and apoptosis in prokaryotic and eukaryotic cells. In plants, polyamines have special roles in stress response and in plant survival. The polyamine metabolism in cyanobacteria in response to environmental stress is of interest in research on stress tolerance of higher plants. In this thesis, the potd gene encoding an polyamine transporter subunit from Synechocystis sp. strain PCC 6803 was characterized for the first time. A homology model built for PotD protein indicated that it has capability of binding polyamines, with the preference for spermidine. Furthermore, in order to investigate the structural features of the substrate specificity, polyamines were docked into the binding site. Spermidine was positioned very similarly in Synechocystis PotD as in the template structure and had most favorable interactions of the docked polyamines. Based on the homology model, experimental work was conducted, which confirmed the binding preference. Flavodiiron proteins (Flv) are enzymes, which protect the cell against toxicity of oxygen and/or nitric oxide by reduction. In this thesis, we present a novel type of photoprotection mechanism in cyanobacteria by the heterodimer of Flv2/Flv4. The constructed homology model of Flv2/Flv4 suggests a functional heterodimer capable of rapid electron transfer. The unknown protein sll0218, encoded by the flv2-flv4 operon, is assumed to facilitate the interaction of the Flv2/Flv4 heterodimer and energy transfer between the phycobilisome and PSII. Flv2/Flv4 provides an alternative electron transfer pathway and functions as an electron sink in PSII electron transfer.

Tuotemallin ylläpito- ja pienkehitysprosessin kehittäminen

Työn tavoitteena oli selvittää yrityksen tuotekehitysorganisaation tuoteylläpitotoiminnan nykytila ja kartoittaa sen mahdolliset ongelmakohdat sekä kehityskohteet. Lisäksi tavoitteena oli vertailla yrityksen toimintamalleja toisen yrityksen vastaavaan organisaatioon kartoitettujen ongelmakohtien pohjalta, ja laatia kehitysehdotus ongelmien ratkaisemiseksi. Tutkimusmenetelminä käytettiin nykytilaselvityksessä semistrukturoituja asiantuntijahaastatteluja ja vertailututkimusta (engl. benchmarking). Kehitysehdotuksen laatimisen tueksi työhön sisältyi myös kirjallisuuskatsaus, jossa käsiteltiin esimerkiksi tuotteen elinkaarenhallintaa, konfiguraationhallintaa ja prosessijohtamista. Nykytilaselvityksen tuloksena oli kuvaus yrityksen tuoteylläpidontoiminnasta sekä havaituista ongelmakohdista. Vertailututkimuksen tuloksena saatiin kuvaus kohdeyrityksen kartoitettuihin ongelmakohtiin liittyvistä toimintamalleista, sekä joitain ratkaisuvaihtoehtoja. Nykytilaselvityksen ja vertailututkimuksen tulosten sekä kirjallisuuskatsauksen perusteella laadittu kehitysehdotus perustuu konfiguraationhallintasuunnitelman pohjaan, johon on sisällytetty kaikki ratkaisuehdotukset. Kehitysehdotuksessa esitetyt ratkaisuehdotukset vastaavat lähtökohtaisesti kartoitettuihin ongelmakohtiin, mutta ne vaativat vielä jatkokehittelyä. Työn tulokset toimivat pohjana yksityiskohtaisemmalle suunnittelulle ja jatkokehittelylle.

Regioselective modification of galactose-containing polysaccharides in aqueous media

Biorefining is defined as sustainable conversion of biomass into marketable products and energy. Forests cover almost one third of earth’s land area, and account for approximately 40% of the total annual biomass production. In forest biorefining, the wood components are, in addition to the traditional paper and board products, converted into chemicals and biofuels. The major components in wood are cellulose, hemicelluloses, and lignin. The main hemicellulose in softwoods, which are of interest especially for the Nordic forest industry, is O-acetyl galactoglucomannan (GGM). GGM can be isolated in industrial scale from the waste waters of the mechanical pulping process, but is not yet today industrially utilized. In order to attain desired properties of GGM for specific end-uses, chemical and enzymatic modifications can be performed. Regioselective modifications of GGM, and other galactose-containing polysaccharides were done by oxidations, and by combining oxidations with subsequent derivatizations of the formed carbonyl or carboxyl groups. Two different pathways were investigated: activation of the C-6 positions in different sugar units by TEMPO-mediated oxidation, and activation of C-6 position in only galactose-units by oxidation catalyzed by the enzyme galactose oxidase. The activated sites were further selectively derivatized; TEMPO-oxidized GGM by a carbodiimide-mediated reaction forming amides, and GO-oxidized GGM by indium-mediated allylation introducing double or triple bonds to the molecule. In order to better understand the reaction, and to develop a MALDI-TOF-MS method for characterization of regioselectively allylated GGM, α-D-galactopyranoside and raffinose were used as model compounds. All reactions were done in aqueous media. To investigate the applicability of the modified polysaccharides for, e.g., cellulose surface functionalization, their sorption onto pulp fibres was studied. Carboxylation affects the sorption tendency significantly; a higher degree of oxidation leads to lower sorption. By controlling the degree of oxidation of the polysaccharides and the ionic strength of the sorption media, high degrees of sorption of carboxylated polysaccharides onto cellulose could, however, be obtained. Anionic polysaccharides were used as templates during laccase-catalyzed polymerization of aniline, offering a green, chemo-enzymatic route for synthesis of conducting polyaniline (PANI) composite materials. Different polysaccharide templates, such as, native GGM, TEMPO-oxidized GGM, naturally anionic κ-carrageenan, and nanofibrillated cellulose produced by TEMPO-oxidation, were assessed. The conductivity of the synthesized polysaccharide/PANI biocomposites varies depending on the polysaccharide template; κ-CGN, the anionic polysaccharide with the lowest pKa value, produces the polysaccharide/PANI biocomposites with the highest conductivity. The presented derivatization, sorption, and polymerization procedures open new application windows for polysaccharides, such as spruce GGM. The modified polysaccharides and the conducting biocomposites produced provide potential applications in biosensors, electronic devices, and tissue engineering.

Characterization of Lubricating Oil Using Ultrasound

This paper presents an ultrasonic method to measure small concentrations of water in lubricating oil. It uses an ultrasonic measurement cell composed by a piezoceramic emitter (5 and 10 MHz), and a large aperture PVDF receiver that eliminates diffraction effects. The propagation velocity, attenuation coefficient and density of several samples of water-in-oil emulsion were measured. The concentrations of water of the samples were in the range of 0 to 5% in volume, and the results showed that these low concentrations can be discriminated within a resolution of 0.2% in the studied range, using the measurement of the propagation velocity.

The pH-dependent phase distribution of wood pitch components in papermaking processes

Wood contains only a very small amount of lipophilic extractives, commonly known as wood pitch. The pitch is known to cause severe problems in papermaking processes. The amount of pitch in process waters can be decreased by seasoning of the raw material prior to pulping, pulp washing, removal of pitch by flotation, adsorption of pitch onto various mineral surfaces, and retention of pitch to the fibre material by cationic polymers. The aim of this study was to determine the influence of pH on some of the methods used for pitch control. Experiments were performed using laboratory-made wood pitch emulsions with varying pH, salt concentration, hemicellulose concentration and pitch composition. These emulsions were used to study the phase distribution of resin and fatty acids, the colloidal stability of pitch with and without steric stabilisation by galactoglucomannans, and the interactions between wood pitch and mineral particles. Purification of unbleached and peroxidebleached mill process water was performed by froth flotation in combination with a foaming agent. The distribution of resin and fatty acids (RFAs) between colloidal pitch droplets and the water phase was very dependent on pH. At pH 3, almost all of the RFAs were attached to the pitch droplets, while increasing the pH led to increasing concentration of dissolved RFAs in the water phase. The presence of salt shifted the release of RFAs towards higher pH, while lower ratio of neutral pitch in the emulsion resulted in release of RFAs at lower pH. It was also seen that the dissolution and adsorption of RFAs at sudden pHchanges takes place very quickly. Colloidal pitch was more stable against electrolyte-induced aggregation at higher pH, due to its higher anionic charge. The concentration of cationic polymers needed to aggregate colloidal pitch also increased with increasing pH. The surface characteristics of solid particles, such as amount of charged groups, were very important for understanding their interactions with colloidal wood pitch. Water-soluble galactoglucomannans stabilised the colloidal pitch sterically against aggregation, but could not completely prevent interactions between wood pitch and hydrophilic particles. Froth flotation of unbleached and peroxidebleached process water showed that the pitch could be removed more effectively and selectively at low pH, compared to at neutral pH. The pitch was removed more effectively, using lower concentrations of foaming agent, from peroxide-bleached water than from unbleached water. The results show that pH has a major impact on various pulping and papermaking processes. It determines the anionic charge of the colloidal pitch and the solubility of certain pitch components. Because of this, the pH influences the effectiveness of pitch retention and removal of pitch. The results indicate that pitch problems could be diminished by acknowledging the importance of pH in various papermaking processes.

The adjustment from Russia to Finland for corporate repatriates: How the repatriation experience influences readjustment in the workplace

To manage foreign operations, companies must often send their employees on international assignments. Repatriating these expatriates can be difficult because they have been forgotten during their posting, and their new experiences are not utilised. In addition to the possible difficulties in organisational repatriation, the returnee can suffer from readjustment problems after a lengthy stay abroad has changed their habits and even identity. This thesis examines the repatriation experience of Finnish assignees returning from Russia. The purpose of the study is to understand how the repatriation experience influences their readjustment to work in Finland. This experience is influenced by many factors including personal and situational changes, the repatriation process, job and organisational factors, and individual’s motives. The theoretical background of the study is founded on two models of repatriation adjustment. A refined, holistic theoretical framework for the study is created. It describes the formation of the repatriation experience and its importance for readjustment to work and retention. The qualitative research approach is suitable for the thesis which examines the returnees’ personal experiences and feelings: a qualitative case study aims to explain the phenomenon in-depth and comprehensively. The data was collected in summer 2013 through semi-standardised interviews with eight Finnish repatriates. They had returned from Russia within the last two years. The data was analysed by structuring the interview transcripts using template analysis. The results supported earlier literature and suggest that the re-entry remains a challenging phase for both the individual and the company. For some, adjusting to a new job was difficult for various reasons. The repatriates underwent personal change and development and felt it was for the better. Many repatriates criticised the company’s repatriation process upon return. Finding a suitable return job was not clear. Instead, the returnees had to be active in finding a new position. Many assignees had only modest career-related motives regarding the assignment and they had realistic expectations about the return. Therefore they were not extremely surprised or dissatisfied when they were not actively offered positions or support by the company. The significance of motives stood out even more than the theory predicted. As predicted, they are linked to the expectations of employees. Moreover, if the employees are motivated to remain in the company, they can tolerate partly a negative repatriation experience. Despite the complexity of the return and readjustment, the assignment as a whole was seen as a rewarding experience by all participants.

Synthesis, characterization and chemical sensor application of conducting polymers

Polymeric materials that conduct electricity are highly interesting for fundamental studies and beneficial for modern applications in e.g. solar cells, organic field effect transistors (OFETs) as well as in chemical and bio‐sensing. Therefore, it is important to characterize this class of materials with a wide variety of methods. This work summarizes the use of electrochemistry also in combination with spectroscopic methods in synthesis and characterization of electrically conducting polymers and other π‐conjugated systems. The materials studied in this work are intended for organic electronic devices and chemical sensors. Additionally, an important part of the presented work, concerns rational approaches to the development of water‐based inks containing conducting particles. Electrochemical synthesis and electroactivity of conducting polymers can be greatly enhanced in room temperature ionic liquids (RTILs) in comparison to conventional electrolytes. Therefore, poly(para‐phyenylene) (PPP) was electrochemically synthesized in the two representative RTILs: bmimPF6 and bmiTf2N (imidazolium and pyrrolidinium‐based salts, respectively). It was found that the electrochemical synthesis of PPP was significantly enhanced in bmimPF6. Additionally, the results from doping studies of PPP films indicate improved electroactivity in bmimPF6 during oxidation (p‐doping) and in bmiTf2N in the case of reduction (n‐doping). These findings were supported by in situ infrared spectroscopy studies. Conducting poly(benzimidazobenzophenanthroline) (BBL) is a material which can provide relatively high field‐effect mobility of charge carriers in OFET devices. The main disadvantage of this n‐type semiconductor is its limited processability. Therefore in this work BBL was functionalized with poly(ethylene oxide) PEO, varying the length of side chains enabling water dispersions of the studied polymer. It was found that functionalization did not distract the electrochemical activity of the BBL backbone while the processability was improved significantly in comparison to conventional BBL. Another objective was to study highly processable poly(3,4‐ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) water‐based inks for controlled patterning scaled‐down to nearly a nanodomain with the intention to fabricate various chemical sensors. Developed PEDOT:PSS inks greatly improved printing of nanoarrays and with further modification with quaternary ammonium cations enabled fabrication of PEDOT:PSS‐based chemical sensors for lead (II) ions with enhanced adhesion and stability in aqueous environments. This opens new possibilities for development of PEDOT:PSS films that can be used in bio‐related applications. Polycyclic aromatic hydrocarbons (PAHs) are a broad group of π‐conjugated materials consisting of aromatic rings in the range from naphthalene to even hundred rings in one molecule. The research on this type of materials is intriguing, due to their interesting optical properties and resemblance of graphene. The objective was to use electrochemical synthesis to yield relatively large PAHs and fabricate electroactive films that could be used as template material in chemical sensors. Spectroscopic, electrochemical and electrical investigations evidence formation of highly stable films with fast redox response, consisting of molecules with 40 to 60 carbon atoms. Additionally, this approach in synthesis, starting from relatively small PAH molecules was successfully used in chemical sensor for lead (II).

Risk Assessment of a Supplier in the Pharmaceutical Industry

The topic of this Master’s Thesis is risk assessment in the supply chain, and the work was done for a company operating in the pharmaceutical industry. The unique features of the industry bring additional challenges to risk management, due to high regulatory, docu-mentation and traceability requirements. The objective of the thesis was to generate a template for assessing the risks in the supply chain of current and potential suppliers of the case company. Risks pertaining to the case setting were sought mainly from in-house expertise of this specific product and supply chain as well as academic research papers and theory on risk management. A questionnaire was set up to assess the found risks on impact, occurrence and possibility of detection. Through this classification of the severity of the risks, the supplier assessment template was formed. A questionnaire template, comprised of the top 10 risks affecting the flow of information and materials in this setting, was formulated to serve as a generic tool for assessing risks in the supply chain of a pharmaceutical company. The template was tested on another supplier for usability and accuracy of found risks, and it demonstrated functioning in a differing supply chain and product setting.

Membrane development for oil contaminated water treatments

The aim of this Master’s thesis study was to develop a membrane for oil contaminated water treatments. Oily wastewaters are a big problem to environment and therefore it is important to find an efficient method for their treatment. There are several treatment methods, but one of the most promising methods is membrane filtration. In the theoretical part of this study the membrane technology and polymeric membrane preparation with phase inversion and membrane modification methods was discussed. It was also told about the most important properties of the membranes. Oily waters, their treatment methods and oily wastewater sources were discussed more specifically. In the experimental part membranes from cellulose acetate were prepared and membranes were modified with two different methods. Modification methods were surface modification and polymer mixing. The modification purpose was to make membranes more hydrophilic and increase surface charge, which can reduce fouling. Membranes were characterized by determining zeta potential, contact angle, oil retention, pure water permeability, pressure-normalized flux and fouling. It were used both synthetic and real spent oil-water emulsion in membrane filtration. Surface modification resulted membranes, which had better properties than unmodified membrane. The amount of substance used in surface modification affected a lot to membrane properties, so it would be necessary to try different amounts of substance to develop the best membrane for oil-water emulsion treatment.

Autoradiographic thyroid evaluation in short-term experimental diabetes mellitus

Previous studies have shown that in vitro thyroid peroxidase (TPO) iodide oxidation activity is decreased and thyroid T4-5'-deiodinase activity is increased 15 days after induction of experimental diabetes mellitus (DM). In the present study we used thyroid histoautoradiography, an indirect assay of in vivo TPO activity, to determine the possible parallelism between the in vitro and in vivo changes induced by experimental DM. DM was induced in male Wistar rats (about 250 g body weight) by a single ip streptozotocin injection (45 mg/kg), while control (C) animals received a single injection of the vehicle. Seven and 30 days after diabetes induction, each diabetic and control animal was given ip a tracer dose of 125I (2 µCi), 2.5 h before thyroid excision. The glands were counted, weighed, fixed in Bouin's solution, embedded in paraffin and cut. The sections were stained with HE and exposed to NTB-2 emulsion (Kodak). The autohistograms were developed and the quantitative distribution of silver grains was evaluated with a computerized image analyzer system. Thyroid radioiodine uptake was significantly decreased only after 30 days of DM (C: 0.38 ± 0.05 vs DM: 0.20 ± 0.04%/mg thyroid, P<0.05) while in vivo TPO activity was significantly decreased 7 and 30 days after DM induction (C: 5.3 and 4.5 grains/100 µm2 vs DM: 2.9 and 1.6 grains/100 µm2, respectively, P<0.05 ). These data suggest that insulin deficiency first reduces in vivo TPO activity during short-term experimental diabetes mellitus

Heterogeneous mass transfer in fluidized beds by computational fluid dynamics

The main objective of this research is to estimate and characterize heterogeneous mass transfer coefficients in bench- and pilot-scale fluidized bed processes by the means of computational fluid dynamics (CFD). A further objective is to benchmark the heterogeneous mass transfer coefficients predicted by fine-grid Eulerian CFD simulations against empirical data presented in the scientific literature. First, a fine-grid two-dimensional Eulerian CFD model with a solid and gas phase has been designed. The model is applied for transient two-dimensional simulations of char combustion in small-scale bubbling and turbulent fluidized beds. The same approach is used to simulate a novel fluidized bed energy conversion process developed for the carbon capture, chemical looping combustion operated with a gaseous fuel. In order to analyze the results of the CFD simulations, two one-dimensional fluidized bed models have been formulated. The single-phase and bubble-emulsion models were applied to derive the average gas-bed and interphase mass transfer coefficients, respectively. In the analysis, the effects of various fluidized bed operation parameters, such as fluidization, velocity, particle and bubble diameter, reactor size, and chemical kinetics, on the heterogeneous mass transfer coefficients in the lower fluidized bed are evaluated extensively. The analysis shows that the fine-grid Eulerian CFD model can predict the heterogeneous mass transfer coefficients quantitatively with acceptable accuracy. Qualitatively, the CFD-based research of fluidized bed process revealed several new scientific results, such as parametrical relationships. The huge variance of seven orders of magnitude within the bed Sherwood numbers presented in the literature could be explained by the change of controlling mechanisms in the overall heterogeneous mass transfer process with the varied process conditions. The research opens new process-specific insights into the reactive fluidized bed processes, such as a strong mass transfer control over heterogeneous reaction rate, a dominance of interphase mass transfer in the fine-particle fluidized beds and a strong chemical kinetic dependence of the average gas-bed mass transfer. The obtained mass transfer coefficients can be applied in fluidized bed models used for various engineering design, reactor scale-up and process research tasks, and they consequently provide an enhanced prediction accuracy of the performance of fluidized bed processes.