Removal of chromium (vi) in aqueous environments using cork and heat-treated cork samples from quercus cerris and quercus suber

Chromium (VI) removal and its reduction to chromium (III) from aqueous solution by untreated and heat-treated Quercus cerris and heat-treated Quercus suber black agglomerate cork granules was investigated. Initial screening studies revealed that among the sorbents tested, untreated Q. cerris and Q. suber black agglomerate are the most efficient in the removal of Cr(VI) ions and were selected for adsorption essays. Heat treatment adversely affected chromium adsorption and chromium (VI) reduction in Q. cerris cork. The highest metal uptake was found at pH 3.0 for Q. cerris and pH 2.0 for black agglomerate. The experimental data fitted the Langmuir model and the calculated qmax was 22.98 mg/g in black agglomerate and 21.69 mg/g in untreated Q. cerris cork. The FTIR results indicated that while in black agglomerate, lignin is the sole component responsible for Cr(VI) sorption, and in untreated Q. cerris cork, suberin and polysaccharides also play a significant role on the sorption. The SEM-EDX results imply that chromium has a homogenous distribution within both cork granules. Also, phloemic residues in Q. cerris granules showed higher chromium concentration. The results obtained in this study show that untreated Q. cerris and black agglomerate cork granules can be an effective and economical alternative to more costly materials for the treatment of liquid wastes containing chromium

A three dimensional study of heat transfer in a supercritical circulating fluidized bed combustor

From the boiler design point of view, it is imperative to know and understand the operation of the boiler. Since comprehensive measurement of a large furnace is impossible, the furnace can be modeled in order to study its behavior and phenomena. This requires the used model to be validated to correspond with the physical furnace behavior. In this thesis, a three dimensional furnace model is validated to match a bituminous coal utilizing, supercritical once-through circulating fluidized bed combustor based on measurement data. The validated model is used for analyzing the furnace heat transfer. Other heat transfer analysis methods are energy balance method based on tube surface temperature measurements and a method based on measured temperature difference between the tube crest and the fin. The latter method was developed in the thesis using Fluent-software. In the theory part, literature is reviewed and the fundamental aspects of circulating fluidized bed are discussed. These aspects are solid particle behavior in fluidization known as hydrodynamics, behavior of fuel and combustion and heat transfer. Fundamental aspects of modeling are also presented.

Statistical Analysis and Numerics of Heat Exchanger Models

The identifiability of the parameters of a heat exchanger model without phase change was studied in this Master’s thesis using synthetically made data. A fast, two-step Markov chain Monte Carlo method (MCMC) was tested with a couple of case studies and a heat exchanger model. The two-step MCMC-method worked well and decreased the computation time compared to the traditional MCMC-method. The effect of measurement accuracy of certain control variables to the identifiability of parameters was also studied. The accuracy used did not seem to have a remarkable effect to the identifiability of parameters. The use of the posterior distribution of parameters in different heat exchanger geometries was studied. It would be computationally most efficient to use the same posterior distribution among different geometries in the optimisation of heat exchanger networks. According to the results, this was possible in the case when the frontal surface areas were the same among different geometries. In the other cases the same posterior distribution can be used for optimisation too, but that will give a wider predictive distribution as a result. For condensing surface heat exchangers the numerical stability of the simulation model was studied. As a result, a stable algorithm was developed.

Effect of reducing and replacing pork fat on the physicochemical, instrumental and sensory characteristics throughout storage time of small caliber non-acid fermented sausages with reduced sodium content

The effect of pork fat reduction (from 44% to 20% final fat content) and its partial substitution by sunflower oil (3% addition) on the physicochemical, instrumental and sensory properties throughout storage time of small caliber non-acid fermented sausages (fuet type) with reduced sodium content (with partial substitution of NaCl by KCl and K-lactate) and without direct addition of nitrate and nitrite (natural nitrate source used instead), was studied. Results showed that sausages with reduced fat (10% initial fat content) and with acceptable sensory characteristics can be obtained by adding to the shoulder lean (8% fat content) during the grinding, either 3.3% backfat (3% fat content) or 3% sunflower oil, both previously finely comminuted with lean. Furthermore, sunflower oil showed to be suitable for partial pork backfat substitution in very lean fermented sausages, conferring desirable sensory properties similar to those of sausages with standard fat content. The sensory quality of the sausages was maintained after three-month cold storage in modified atmosphere.

Moisture sorption isotherms and isosteric heat determination in Chilean papaya (Vasconcellea pubescens)

The moisture sorption isotherms of Chilean papaya were determined at 5, 20, and 45 ºC, over a relative humidity range of 10-95%. The GAB, BET, Oswin, Halsey, Henderson, Smith, Caurie and Iglesias-Chirife models were applied to the sorption experimental data. The goodness of fit of the mathematical models was statistically evaluated by means of the determination coefficient, mean relative percentage deviation, sum square error, root-mean-square error, and chi-square values. The GAB, Oswin and Halsey models were found to be the most suitable for the description of the sorption data. The sorption heats calculated using the Clausius-Clapeyron equation were 57.35 and 59.98 kJ·mol-1, for adsorption and desorption isotherms, respectively.

Kinetics of oxidation of biodiesel from soybean oil mixed with TBHQ: determination of storage time

Synthetic antioxidants are an alternative to prevent or retard the degradation of biofuels made from vegetable oils. In this study, it was evaluated the oxidative stability of B100 soybean oil biodiesel, in the presence of tercbutylhydroquinone (TBHQ). The results showed that the induction period, that precedes the seeding process, was delayed in the presence of the antioxidant. Moreover, the obtained results suggest that the B100 biodiesel containing TBHQ can present a storage time at 25 ºC, three times longer than the estimated time for the pure B100.

METODOLOGIAS DE COLETA, PRESERVAÇÃO E ARMAZENAMENTO DE AMOSTRAS DE ÁGUA PARA ANÁLISE DE MERCÚRIO - UMA REVISÃO

Knowing the mercury levels of an environment allows a diverse array of biogeochemical studies into the mercury cycle on a local or global scale. Among matrices commonly evaluated, water remains a challenge for research because its mercury levels can be very low, requiring development of complex analytical protocols. Currently, sample preservation methods, protocols that avoid contamination, and analytical techniques with low detection limits allow analysis of mercury in pristine waters. However, different protocols suggest different methods depending on a range of factors such as the characteristics of water sampled and storage time. In remote areas, such as oceanic and Amazonian regions, sample preservation and transport to a laboratory can be difficult, requiring processing of the water during the sampling expedition and the establishment of a field laboratory. Brazilian research on mercury in water can be limited due to difficulty obtaining reagents, lack of laboratory structure, qualified personnel, and financial support. Considering this complexity for analyzing water, we reviewed methodologies for sampling, preservation, and storage of water samples for analysis of the most commonly evaluated mercury species (dissolved gaseous mercury, reactive mercury, methylmercury and total mercury).

Fungicides, seed dresser adjuvants and storage time in the control of Drechslera teres in barley seeds

In experiments conducted in laboratory, the effect of fungicides, seed dresser adjuvants and storage time in the control of Drechslera teres in seeds of barley cultivar BRS Elis, with 58% incidence, was quantified. Fungicides indicated by barley research (carboxin + thiram, difenoconazole and triadimenol) compared with the mixture carbendazim + iprodione were tested. As seed dresser adjuvants, water (500m mL/100 Kg) and a polymer (150 mL/100 Kg) were used. Treated seeds were stored in paper bags and kept in the refrigerator at 5ºC. At 30-day intervals during six months, seeds were plated on semi-selective Reis's medium (1983). The best control was obtained by the mixtures carboxin + thiram and carbendazim + iprodione and the polymer as seed dresser. The control efficiency was improved by the storage time without negatively affecting seed germination. Due to the transmission efficiency, the fungus eradication in seeds should be pursued.

Mycobiota evolution during storage of paddy, brown and milled rice in different genotypes

The rice grain is frequently infected by a series of pathogens (fungi) during its storage, producing damages to the economy and health of humans. The aim of this study was to identify the fungal genera present in different rice genotypes and to quantify their variation during storage. Paddy, brown and milled rice fractions of Nutriar, (N) H329-5(H329) and Don Ignacio genotypes were analyzed at 4, 8 and 12 months of storage. Fungi were identified based on their micromorphological characteristics and colonies. The observed genera according to their frequency were: Alternaria, Nigrospora, Epicoccum, Bipolaris, Curvularia, Cladosporium and Fusarium (field fungi) and Penicillium and Aspergillus (storage fungi). The mycobiota composition was different depending on the grain fraction and the period of storage: field fungi were located in the hulls and bran layers, while storage fungi were mainly in the endosperm. The different genotypes showed different susceptibility to contamination.

Influence of Heat Treatment on Strength Properties of Finger-jointed Components

The purpose for the thesis was to study the thermo treatment of finger-jointed wood. The thesis concentrated on examining the tensile and bending strength of finger-jointed and thermo treated wood. The aim was to find out how different treatment temperature levels and adhesives influence the strength of wood that has been finger-jointed before heat treatment. Secondary objectives were to examine the influence of the treatment time at one temperature, determine differences in the strength between the joints in heartwood and sapwood, examine the visual appearance of the finger joints after the treatment and establish possibilities to reach a characteristic strength level corresponding to C14. Only minor differences in strength properties were measured between the finger-jointed wood treatments II and III. A greater difference was shown between these two treatment temperatures I, which lead to reduced strength. The average strength of joints glued with adhesive 2 was higher after treatments II and III compared to those glued with the adhesive 1. At the treatment temperature I, the adhesive 1 strength properties were at the same level compared to the adhesive 2 or better. There were not any significant differences.

Methods for construction and analysis of computational models in systems biology : applications to the modelling of the heat shock response and the self-assembly of intermediate filaments

Systems biology is a new, emerging and rapidly developing, multidisciplinary research field that aims to study biochemical and biological systems from a holistic perspective, with the goal of providing a comprehensive, system- level understanding of cellular behaviour. In this way, it addresses one of the greatest challenges faced by contemporary biology, which is to compre- hend the function of complex biological systems. Systems biology combines various methods that originate from scientific disciplines such as molecu- lar biology, chemistry, engineering sciences, mathematics, computer science and systems theory. Systems biology, unlike “traditional” biology, focuses on high-level concepts such as: network, component, robustness, efficiency, control, regulation, hierarchical design, synchronization, concurrency, and many others. The very terminology of systems biology is “foreign” to “tra- ditional” biology, marks its drastic shift in the research paradigm and it indicates close linkage of systems biology to computer science. One of the basic tools utilized in systems biology is the mathematical modelling of life processes tightly linked to experimental practice. The stud- ies contained in this thesis revolve around a number of challenges commonly encountered in the computational modelling in systems biology. The re- search comprises of the development and application of a broad range of methods originating in the fields of computer science and mathematics for construction and analysis of computational models in systems biology. In particular, the performed research is setup in the context of two biolog- ical phenomena chosen as modelling case studies: 1) the eukaryotic heat shock response and 2) the in vitro self-assembly of intermediate filaments, one of the main constituents of the cytoskeleton. The range of presented approaches spans from heuristic, through numerical and statistical to ana- lytical methods applied in the effort to formally describe and analyse the two biological processes. We notice however, that although applied to cer- tain case studies, the presented methods are not limited to them and can be utilized in the analysis of other biological mechanisms as well as com- plex systems in general. The full range of developed and applied modelling techniques as well as model analysis methodologies constitutes a rich mod- elling framework. Moreover, the presentation of the developed methods, their application to the two case studies and the discussions concerning their potentials and limitations point to the difficulties and challenges one encounters in computational modelling of biological systems. The problems of model identifiability, model comparison, model refinement, model inte- gration and extension, choice of the proper modelling framework and level of abstraction, or the choice of the proper scope of the model run through this thesis.

Evaluation of the physiological quality of anadenenthera peregrina (L.) Speg. seeds during storage

The aim of this experiment was to evaluate the effect of storage temperature on the viability and vigour of A. peregrina seeds. Seeds of A. peregrina harvested in Viçosa-MG, in September 2005 were used. The seeds were stored in the Laboratory of Forest Seeds Analysis (LASF) of the Universidade Federal de Viçosa (UFV), in a cold chamber, under approximately 5ºC over150 days. The seeds were stored under 20ºC for 150 days more. Seed moisture was determined after oven-drying at 105 ± 3ºC for 24 hours. The seeds were analyzed monthly using germination, tetrazolium and electrical conductivity tests and Osmopriming during 300 days, with four repetitions of 25 seeds. A. peregrina seeds kept a constant percentage of germination and viable seeds under the tetrazolium test for five months of storage, under either 5ºC and 20ºC. The electrical conductivity test showed significant differences in relation to the storage period, proving to be more sensitive than the standard germination test. Seed priming in PEG -0,4 MPa solution was not efficient in recovering the viability and vigor of the stored seeds at 5ºC and 20ºC.

Role and regulatory mechanisms of heat shock factor 2

Protein homeostasis is essential for cells to prosper and survive. Various forms of stress, such as elevated temperatures, oxidative stress, heavy metals or bacterial infections cause protein damage, which might lead to improper folding and formation of toxic protein aggregates. Protein aggregation is associated with serious pathological conditions such as Alzheimer’s and Huntington’s disease. The heat shock response is a defense mechanism that protects the cell against protein-damaging stress. Its ancient origin and high conservation among eukaryotes suggest that the response is crucial for survival. The main regulator of the heat shock response is the transcription factor heat shock factor 1 (HSF1), which induces transcription of genes encoding protective molecular chaperones. In vertebrates, a family of four HSFs exists (HSF1-4), with versatile functions not only in coping with acute stress, but also in development, longevity and cancer. Thus, knowledge of the HSFs will aid in our understanding on how cells survive suboptimal circumstances, but will also provide insights into normal physiological processes as well as diseaseassociated conditions. In this study, the function and regulation of HSF2 have been investigated. Earlier gene inactivation experiments in mice have revealed roles for HSF2 in development, particularly in corticogenesis and spermatogenesis. Here, we demonstrate that HSF2 holds a role also in the heat shock response and influences stress-induced expression of heat shock proteins. Intriguingly, DNA-binding activity of HSF2 upon stress was dependent on the presence of intact HSF1, suggesting functional interplay between HSF1 and HSF2. The underlying mechanism for this phenomenon could be configuration of heterotrimers between the two factors, a possibility that was experimentally verified. By changing the levels of HSF2, the expression of HSF1-HSF2 heterotrimer target genes was altered, implementing HSF2 as a modulator of HSF-mediated transcription. The results further indicate that HSF2 activity is dependent on its concentration, which led us to ask the question of how accurate HSF2 levels are achieved. Using mouse spermatogenesis as a model system, HSF2 was found to be under direct control of miR-18, a miRNA belonging to the miR-17~92 cluster/Oncomir-1 and whose physiological function had remained unclear. Investigations on spermatogenesis are severely hampered by the lack of cell systems that would mimic the complex differentiation processes that constitute male germ cell development. Therefore, to verify that HSF2 is regulated by miR-18 in spermatogenesis, a novel method named T-GIST (Transfection of Germ cells in Intact Seminiferous Tubules) was developed. Employing this method, the functional consequences of miR-18-mediated regulation in vivo were demonstrated; inhibition of miR- 18 led to increased expression of HSF2 and altered the expression of HSF2 target genes Ssty2 and Speer4a. Consequently, the results link miR-18 to HSF2-mediated processes such as germ cell maturation and quality control and provide miR-18 with a physiological role in gene expression during spermatogenesis.Taken together, this study presents compelling evidence that HSF2 is a transcriptional regulator in the heat shock response and establishes the concept of physical interplay between HSF2 and HSF1 and functional consequences thereof. This is also the first study describing miRNA-mediated regulation of an HSF.