Heat shock response in photosynthetic organisms: membrane and lipid connections.

The ability of photosynthetic organisms to adapt to increases in environmental temperatures is becoming more important with climate change. Heat stress is known to induce heat-shock proteins (HSPs) many of which act as chaperones. Traditionally, it has been thought that protein denaturation acts as a trigger for HSP induction. However, increasing evidence has shown that many stress events cause HSP induction without commensurate protein denaturation. This has led to the membrane sensor hypothesis where the membrane's physical and structural properties play an initiating role in the heat shock response. In this review, we discuss heat-induced modulation of the membrane's physical state and changes to these properties which can be brought about by interaction with HSPs. Heat stress also leads to changes in lipid-based signaling cascades and alterations in calcium transport and availability. Such observations emphasize the importance of membranes and their lipids in the heat shock response and provide a new perspective for guiding further studies into the mechanisms that mediate cellular and organismal responses to heat stress.

Fertilidade do solo e estado nutricional do cafeeiro cultivado em atmosfera enriquecida com CO2

Resumo: O objetivo deste trabalho foi avaliar os efeitos de concentra����es de CO2 atmosf��rico nos atributos qu��micos do solo, na linha (cafeeiro) e na entrelinha (braqui��ria), e nos teores de macronutrientes em folhas do cafeeiro. Utilizou-se o delineamento de blocos ao acaso, com parcelas subdivididas e seis repeti����es. Os tratamentos consistiram de dois n��veis de CO2 atmosf��rico, 390 e 550 μmol mol-1. A amostragem de solo foi realizada na linha e na entrelinha do cafeeiro, em 2013 e 2014, nas camadas de 0-5,0, 5,0-10, 10-20 e 20-40 cm, e de 0-10, 10-20 e 20-40 cm, respectivamente. Avaliaram-se pH, teores de Ca2+, Mg2+, K, P e S dispon��veis, satura����o por bases e mat��ria org��nica do solo. Em 2013 e 2014, houve redu����o nos teores de P na linha do cafeeiro, com o aumento da concentra����o de CO2. Em 2014, houve redu����o nos teores de K dispon��vel no solo e aumento dos teores de K na folha do cafeeiro sob 550 μmol mol-1 de CO2. Em cafeeiro cultivado em atmosfera enriquecida com CO2, o teor de P dispon��vel no solo �� o que mais reduz, o que indica a necessidade de reposi����o adequada deste nutriente.

IRF-3 partners Bax in a viral-induced dance macabre.

In this issue of The EMBO Journal, Chattopadhyay et al (2010) describe a surprising new mechanism for how viral dsRNA detection by the RIG-I/MAVS signalling complex can initiate apoptosis. Independent of its transcriptional function, a pool of interferon regulatory factor (IRF)-3 activated downstream of MAVS can bind to and activate cytosolic Bax, resulting in Bax translocation to the mitochondria and initiation of the intrinsic apoptotic pathway.

Contributions of the peroxisome and β-oxidation cycle to biotin synthesis in fungi.

The first step in the synthesis of the bicyclic rings of D-biotin is mediated by 8-amino-7-oxononanoate (AON) synthase, which catalyzes the decarboxylative condensation of l-alanine and pimelate thioester. We found that the Aspergillus nidulans AON synthase, encoded by the bioF gene, is a peroxisomal enzyme with a type 1 peroxisomal targeting sequence (PTS1). Localization of AON to the peroxisome was essential for biotin synthesis because expression of a cytosolic AON variant or deletion of pexE, encoding the PTS1 receptor, rendered A. nidulans a biotin auxotroph. AON synthases with PTS1 are found throughout the fungal kingdom, in ascomycetes, basidiomycetes, and members of basal fungal lineages but not in representatives of the Saccharomyces species complex, including Saccharomyces cerevisiae. A. nidulans mutants defective in the peroxisomal acyl-CoA oxidase AoxA or the multifunctional protein FoxA showed a strong decrease in colonial growth rate in biotin-deficient medium, whereas partial growth recovery occurred with pimelic acid supplementation. These results indicate that pimeloyl-CoA is the in vivo substrate of AON synthase and that it is generated in the peroxisome via the β-oxidation cycle in A. nidulans and probably in a broad range of fungi. However, the β-oxidation cycle is not essential for biotin synthesis in S. cerevisiae or Escherichia coli. These results suggest that alternative pathways for synthesis of the pimelate intermediate exist in bacteria and eukaryotes and that Saccharomyces species use a pathway different from that used by the majority of fungi.

Profiling of signal transduction in human memory T cells

R��sum�� pour un large public: La vaccination a eu un impact ��norme sur la sant�� mondiale. Mais, quel est le principe d'un vaccin? Il est bas�� sur la 'm��moire immunologique', qui est une particularit�� exclusive des syst��mes immunitaires des organismes ��volu��s. Suite �� une infection par un pathog��ne, des cellules sp��cialis��es de notre syst��me immunitaire (les lymphocytes) le reconnaissent et initient une r��action immunitaire qui a pour but son ��limination. Pendant cette r��action se d��veloppent aussi des cellules, appel��es cellules lymphocytaires m��moire, qui persistent pour longue dur��e et qui ont la capacit�� de stimuler une r��action immunitaire tr��s efficace imm��diatement apr��s une seconde exposition �� ce m��me pathog��ne. Ce sont ces cellules m��moires (lymphocytes B et T) qui sont �� la base de la 'm��moire immunologique' et qui sont stimul��es lors de la vaccination. Chez l'homme, deux populations distinctes des lymphocytes T m��moires ont ��t�� identifi��es: les cellules centrales (CM) et effectrices (EM) m��moires. Ces populations sont fonctionnellement h��t��rog��nes et exercent des r��les distincts et essentiels dans l'immunit�� protectrice. Typiquement, les cellules effectrices m��moires sont capables de tuer imm��diatement le pathog��ne tandis que les cellules centrales m��moires sont responsables d'initier une r��ponse immunitaire compl��te. Pourtant, les m��canismes biochimiques qui contr��lent les fonctions de ces cellules ont ��t�� jusqu'�� pr��sent peu ��tudi��s �� cause de la faible fr��quence de ces cellules et de la quantit�� limit��e de tissus humains disponibles pour les analyses. La compr��hension de ces m��canismes est cruciale pour la r��alisation de vaccins efficaces et pour le d��veloppement de nouveaux m��dicaments capables de moduler la r��ponse immunitaire lymphocytaire. Dans cette th��se, nous avons d'abord d��velopp�� et am��lior�� une technologie appel��e 'prot��ine array en phase inverse' qui poss��de un niveau de sensibilit�� beaucoup plus ��lev�� par rapport aux technologies classiquement utilis��es dans l'��tude des prot��ines. Gr��ce �� cette technique, nous avons pu comparer la composition prot��ique du syst��me de transmission des signaux d'activation des cellules CM et EM humaines. L'analyse de 8 �� 13 sujets sains a montr�� que ces populations des cellules m��moires poss��dent un syst��me de signalisation prot��ique diff��rent. En effet, les cellules EM poss��dent, par rapport aux cellules CM, des niveaux r��duits d'une prot��ine r��gulatrice (appel��e c-Cbl) que nous avons d��montr�� comme ��tant responsable des fonctions sp��cifiques de ces cellules. En effet, en augmentant artificiellement l'expression de cette prot��ine r��gulatrice dans les cellules EM jusqu'au niveau de celui des cellules CM, nous avons induit dans les cellules EM des capacit��s fonctionnelles caract��ristiques des cellules CM. En conclusion, notre ��tude a identifi��, pour la premi��re fois chez l'homme, un m��canisme biochimique qui contr��le les fonctions des populations des cellules m��moires. R��sum�� en Fran��ais: Les cellules m��moires persistent inertes dans l'organisme et produisent des r��actions immunitaires rapides et robustes contre les pathog��nes pr��c��demment rencontr��s. Deux populations distinctes des cellules m��moires ont ��t�� identifi��es chez l'homme: les cellules centrales (CM) et effectrices (EM) m��moires. Ces populations sont fonctionnellement h��t��rog��nes et exercent des r��les distincts et critiques dans l'immunit�� protectrice. Les m��canismes biochimiques qui contr��lent leurs fonctions ont ��t�� jusqu'�� pr��sent peu ��tudi��s, bien que leur compr��hension soit cruciale pour le d��veloppement des vaccins et des nouveaux traitements/m��dicaments. Les limites majeures �� ces ��tudes sont la faible fr��quence de ces populations et la quantit�� limit��e de tissus humains disponibles. Dans cette th��se nous avons d'abord d��velopp�� et am��lior�� la technologie de 'prot��ine array en phase inverse' afin d'analyser les mol��cules de signalisation des cellules m��moires CD4 et CD8 humaines isol��es ex vivo. L'excellente sensibilit��, la reproductibilit�� et la lin��arit�� de la d��tection, ont permis de quantifier des variations d'expression prot��iques sup��rieures �� 20% dans un lysat ��quivalent �� 20 cellules. Ensuite, gr��ce �� l'analyse de 8 �� 13 sujets sains, nous avons prouv�� que les cellules m��moires CD8 ont une composition homog��ne de leur syst��me de signalisation tandis que les cellules CD4 EM expriment significativement de plus grandes quantit��s de SLP-76 et des niveaux r��duits de c-Cbl, Syk, Fyn et LAT par rapport aux cellules CM. En outre, l'expression r��duite du r��gulateur n��gatif c-Cbl est corr��l��e avec l'expression des SLP-76, PI3K et LAT uniquement dans les cellules EM. L'��valuation des propri��t��s fonctionnelles des cellules m��moires a permis de d��montrer que l'expression r��duite du c-Cbl dans les cellules EM est associ�� �� une diminution de leur seuil d'activation. En effet, gr��ce a la technique de transduction cytosolique, nous avons augment�� la quantit�� de c-Cbl des cellules EM �� un niveau comparable �� celui des cellules CM et constat�� une r��duction de la capacit�� des cellules EM �� prolif��rer et s��cr��ter des cytokines. Ce m��canisme de r��gulation d��pend principalement de l'activit�� d'ubiquitine ligase de c-Cbl comme d��montr�� par l'impact r��duit du mutant enzymatiquement d��ficient de c-Cbl sur les fonctions de cellules EM. En conclusion, cette th��se identifie c-Cbl comme un r��gulateur critique des r��ponses fonctionnelles des populations de cellules T m��moires et fournit, pour la premi��re fois chez l'homme, un m��canisme contr��lant l'h��t��rog��n��it�� fonctionnelle des ces cellules. De plus, elle valide l'utilisation combin��e des 'RPP arrays' et de la transduction cytosolique comme outil puissant d'analyse quantitative et fonctionnel des prot��ines de signalisation. Summary : Memory cells persist in a quiescent state in the body and mediate rapid and vigorous immune responses toward pathogens previously encountered. Two subsets of memory cells, namely central (CM) and effector (EM) memory cells, have been identified in humans. These subsets display high functional heterogeneity and assert critical and distinct roles in the control of protective immunity. The biochemical mechanisms controlling their functional properties remain so far poorly investigated, although their clarification is crucial for design of effective T-cell vaccine and drug development. Major limitations to these studies lie in the low frequency of memory T cell subsets and the limited amount of human specimen available. In this thesis we first implemented the innovative reverse phase protein array approach to profile 15 signalling components in human CD8 and CD4 memory T cells isolated ex vivo. The high degree of sensitivity, reproducibility and linearity achieved, allowed an excellent quantification of variations in protein expression higher than 20% in as few as 20-cell equivalent per spot. Based on the analysis of 8 to 13 healthy subjects, we showed that CD8 memory cells have a homogeneous composition of their signaling machinery while CD4 EM cells express statistically significant increased amounts of SLP-76 and reduced levels of c- Cbl, Syk, Fyn and LAT as compared to CM cells. Moreover, in EM but not CM cells, reduced expression of negative regulator c-Cbl correlated with the expression of SLP-76, PI3K and LAT. Subsequently, we demonstrated that the higher functional properties and the lower functional threshold of EM cells is associated with reduced expression of c-Cbl. Indeed, by increasing c-Cbl content of EM cells to the same level of CM cells using cytosolic transduction, we impaired their proliferation and cytokine production. This regulatory mechanism was primarily dependent on c-Cbl E3 ubiquitin ligase activity as evidenced by the weaker impact of enzymatically deficient c-Cbl C381A mutant on EM cell functions. Together, these results identify c-Cbl as a critical regulator of the functional responses of memory T cell subsets and provides, for the first time in humans, a mechanism controlling the functional heterogeneity of memory CD4 cells. Moreover it validates the combined use of RPP arrays and cytosolic transduction approaches as a powerful tool to quantitatively analyze signalling proteins and functionally assess their roles.

Influence of stationary phase and eluent properties on chromatographic separation of carbohydrates

In this thesis, the sorption and elastic properties of the cation-exchange resins were studied to explain the liquid chromatographic separation of carbohydrates. Na+, Ca2+ and La3+ form strong poly(styrene-co-divinylbenzene) (SCE) as well as Na+ and Ca2+ form weak acrylic (WCE) cation-exchange resins at different cross-link densities were treated within this work. The focus was on the effects of water-alcohol mixtures, mostly aqueous ethanol, and that of the carbohydrates. The carbohydrates examined were rhamnose, xylose, glucose, fructose, arabinose, sucrose, xylitol and sorbitol. In addition to linear chromatographic conditions, non-linear conditions more typical for industrial applications were studied. Both experimental and modeling aspectswere covered. The aqueous alcohol sorption on the cation-exchangers were experimentally determined and theoretically calculated. The sorption model includes elastic parameters, which were obtained from sorption data combined with elasticity measurements. As hydrophilic materials cation-exchangers are water selective and shrink when an organic solvent is added. At a certain deswelling degree the elastic resins go through glass transition and become as glass-like material. Theincreasing cross-link level and the valence of the counterion decrease the sorption of solvent components in the water-rich solutions. The cross-linkage or thecounterions have less effect on the water selectivity than the resin type or the used alcohol. The amount of water sorbed is higher in the WCE resin and, moreover, the WCE resin is more water selective than the corresponding SCE resin. Theincreased aliphatic part of lower alcohols tend to increase the water selectivity, i.e. the resins are more water selective in 2-propanol than in ethanol solutions. Both the sorption behavior of carbohydrates and the sorption differences between carbohydrates are considerably affected by the eluent composition and theresin characteristics. The carbohydrate sorption was experimentally examined and modeled. In all cases, sorption and moreover the separation of carbohydrates are dominated by three phenomena: partition, ligand exchange and size exclusion. The sorption of hydrophilic carbohydrates increases when alcohol is added into the eluent or when carbohydrate is able to form coordination complexes with the counterions, especially with multivalent counterions. Decreasing polarity of the eluent enhances the complex stability. Size exclusion effect is more prominent when the resin becomes tighter or carbohydrate size increases. On the other hand,the elution volumes between different sized carbohydrates decreases with the decreasing polarity of the eluent. The chromatographic separation of carbohydrateswas modeled, using rhamnose and xylose as target molecules. The thermodynamic sorption model was successfully implemented in the rate-based column model. The experimental chromatographic data were fitted by using only one adjustable parameter. In addition to the fitted data also simulated data were generated and utilized in explaining the effect of the eluent composition and of the resin characteristics on the carbohydrate separation.

Reliability of the density functional approximation to describe the charge transfer and electrostatic complexes involved in the modeling of organic conducting polymers

Both the intermolecular interaction energies and the geometries for M �� thiophene, M �� pyrrole, M n+ �� thiophene, and M n+ �� pyrrole ��with M = Li, Na, K, Ca, and Mg; and M n+ = Li+ , Na+ , K+ , Ca2+, and Mg2+�� have been estimated using four commonly used density functional theory ��DFT�� methods: B3LYP, B3PW91, PBE, and MPW1PW91. Results have been compared to those provided by HF, MP2, and MP4 conventional ab initio methods. The PBE and MPW1PW91 are the only DFT methods able to provide a reasonable description of the M �� complexes. Regarding M n+ �� ��� complexes, the four DFT methods have been proven to be adequate in the prediction of these electrostatically stabilized systems, even though they tend to overestimate the interaction energies.

Neuronal survival induced by neurotrophins requires calmodulin

It has been reported that phosphoinositide 3-kinase (PI 3-kinase) and its downstream target, protein kinase B (PKB), play a central role in the signaling of cell survival triggered by neurotrophins (NTs). In this report, we have analyzed the involvement of Ca2+ and calmodulin (CaM) in the activation of the PKB induced by NTs. We have found that reduction of intracellular Ca2+ concentration or functional blockade of CaM abolished NGF-induced activation of PKB in PC12 cells. Similar results were obtained in cultures of chicken spinal cord motoneurons treated with brain-derived neurotrophic factor (BDNF). Moreover, CaM inhibition prevented the cell survival triggered by NGF or BDNF. This effect was counteracted by the transient expression of constitutive active forms of the PKB, indicating that CaM regulates NT-induced cell survival through the activation of the PKB. We have investigated the mechanisms whereby CaM regulates the activation of the PKB, and we have found that CaM was necessary for the proper generation and/or accumulation of the products of the PI 3-kinase in intact cells.

Fontes de c��lcio aplicadas no solo e sua rela����o com a qualidade da uva 'V��nus'

O objetivo deste trabalho foi avaliar o efeito da aplica����o de diferentes fontes de Ca2+ no solo sobre o teor deste nutriente no solo, nas folhas e nos frutos, e sobre atributos f��sico-qu��micos e conserva����o p��s-colheita da uva 'V��nus' (Vitis labrusca x V. vinifera). O delineamento foi em blocos ao acaso, com quatro repeti����es. Utilizaram-se os seguintes tratamentos: T1 - testemunha (sem aplica����o de Ca2+ no solo); T2 - cloreto de c��lcio; T3 - gesso agr��cola; T4 - Nitrabor��; T5 - cal hidratada, e T6 - borra de celulose. Para todas as fontes, aplicou-se o equivalente a 80 kg de Ca2+ ha-1, parcelados em tr��s aplica����es, a cada 21 dias, a partir do in��cio da brota����o da videira. Avaliou-se o teor de macronutrientes no solo, nas folhas e frutos. Na matura����o, foram coletados quatro cachos por parcela, sendo dois cachos avaliados por ocasi��o da colheita e dois cachos mantidos sob temperatura ambiente e atmosfera modificada, sendo avaliados ap��s cinco dias. Em geral, as fontes de Ca2+ proporcionaram maior teor de Ca2+ no solo, nas folhas e nos frutos. O Nitrabor�� e o gesso agr��cola aumentaram o peso m��dio de bagas. As fontes de Ca2+ reduziram a perda de peso, o degrane e a incid��ncia de podrid��es dos frutos em p��s-colheita.

The AMPK family member Snf1 protects Saccharomyces cerevisiae cells upon glutatione oxidation

The AMPK/Snf1 kinase has a central role in carbon metabolism homeostasis in Saccharomyces cerevisiae. In this study, we show that Snf1 activity, which requires phosphorylation of the Thr210 residue, is needed for protection against selenite toxicity. Such protection involves the Elm1 kinase, which acts upstream of Snf1 to activate it. Basal Snf1 activity is sufficient for the defense against selenite, although Snf1 Thr210 phosphorylation levels become increased at advanced treatment times, probably by inhibition of the Snf1 dephosphorylation function of the Reg1 phosphatase. Contrary to glucose deprivation, Snf1 remains cytosolic during selenite treatment, and the protective function of the kinase does not require its known nuclear effectors. Upon selenite treatment, a null snf1 mutant displays higher levels of oxidized versus reduced glutathione compared to wild type cells, and its hypersensitivity to the agent is rescued by overexpression of the glutathione reductase gene GLR1. In the presence of agents such as diethyl maleate or diamide, which cause alterations in glutathione redox homeostasis by increasing the levels of oxidized glutathione, yeast cells also require Snf1 in an Elm1-dependent manner for growth. These observations demonstrate a role of Snf1 to protect yeast cells in situations where glutathione-dependent redox homeostasis is altered to a more oxidant intracellular environment and associates AMPK to responses against oxidative stress.

Up-regulated 14-3-3β and 14-3-3ζ proteins in prefrontal cortex of subjects with schizophrenia: effect of psychotropic treatment.

14-3-3 is a family of conserved regulatory proteins that bind to a multitude of functionally diverse signalling proteins. Various genetic studies and gene expression and proteomic analyses have involved 14-3-3 proteins in schizophrenia (SZ). On the other hand, studies about the status of these proteins in major depressive disorder (MD) are still missing. Immunoreactivity values of cytosolic 14-3-3&#946; and 14-3-3&#950; proteins were evaluated by Western blot in prefrontal cortex (PFC) of subjects with schizophrenia (SZ; n=22), subjects with major depressive disorder (MD; n=21) and age-, gender- and postmortem delay-matched control subjects (n=52). The modulation of 14-3-3&#946; and 14-3-3&#950; proteins by psychotropic medication was also assessed. The analysis of both proteins in SZ subjects with respect to matched control subjects showed increased 14-3-3&#946; (&#916;=33��10%, p<0.05) and 14-3-3&#950; (&#916;=29��6%, p<0.05) immunoreactivity in antipsychotic-free but not in antipsychotic-treated SZ subjects. Immunoreactivity values of 14-3-3&#946; and 14-3-3&#950; were not altered in MD subjects. These results show the specific up-regulation of 14-3-3&#946; and 14-3-3&#950; proteins in PFC of SZ subjects and suggest a possible down-regulation of both proteins by antipsychotic treatment.

The membrane-permeable calmodulin inhibitors (W-7/W-13) bind to membranes changing the electrostatic surface potential. Dual effect of W-13 on EGFR activation

Membrane-permeable calmodulin inhibitors, such as the napthalenesulfonamide derivatives W-7/W-13, trifluoperazine, and calmidazolium, are used widely to investigate the role of calcium/calmodulin (Ca2+/CaM) in living cells. If two chemically different inhibitors (e.g. W-7 and trifluoperazine) produce similar effects, investigators often assume the effects are due to CaM inhibition. Zeta potential measurements, however, show that these amphipathic weak bases bind to phospholipid vesicles at the same concentrations as they inhibit Ca 2 /CaM; this suggests that they also bind to the inner leaflet of the plasma membrane, reducing its negative electrostatic surface potential. This change will cause electrostatically bound clusters of basic residues on peripheral (e.g. Src and K-Ras4B) and integral (e.g. epidermal growth factor receptor (EGFR)) proteins to translocate from the membrane to the cytoplasm. We measured inhibitor-mediated translocation of a simple basic peptide corresponding to the calmodulin-binding juxtamembrane region of the EGFR on model membranes; W-7/W-13 causes translocation of this peptide from membrane to solution, suggesting that caution must be exercised when interpreting the results obtained with these inhibitors in living cells. We present evidence that they exert dual effects on autophosphorylation of EGFR;W-13 inhibits epidermal growth factordependent EGFR autophosphorylation under different experimental conditions, but in the absence of epidermal growth factor, W-13 stimulates autophosphorylation of the receptor in four different cell types. Our interpretation is that the former effect is due toW-13inhibition of Ca 2 /CaM, but thelatter results could be due to binding of W-13 to the plasma membrane.

Atributos f��sicos e qu��micos de um argissolo vermelho, em pomar org��nico de citros com manejo da vegeta����o nas entrelinhas

O manejo em pomares org��nicos de citros �� diferenciado em rela����o aos pomares convencionais. Deste modo, objetivou-se avaliar alguns atributos f��sicos e qu��micos de um Argissolo espessar��nico e produtividade do pomar de tangerineiras, cv. montenegrina, sob sistema org��nico de produ����o, com diferentes manejos da vegeta����o nas entrelinhas. Os tratamentos estudados foram: gradagem, ro��ada, acamamento com rolo-faca e com arraste de tronco. A avalia����o dos atributos f��sicos ocorreu sob a proje����o da copa e na ��rea de tr��fego de m��quinas, nas camadas de 0,0-0,1 e 0,1-0,2 m. A fertilidade qu��mica do solo foi determinada nas profundidades de 0,0-0,1; 0,1-0,2 e 0,2-0,4 m, enquanto a produtividade de frutos foi estimada a partir das plantas centrais de cada parcela. O tr��fego de m��quinas influenciou negativamente nos atributos f��sicos do solo abaixo da interface pneu/solo, embora n��o tenha sido restritivo �� produtividade de frutos. Em todos os tratamentos, houve incremento de mat��ria org��nica na camada superficial do solo e dos teores de P, K+, Ca2+ e Mg2+ nas tr��s camadas de solo em rela����o �� ��rea adjacente com vegeta����o nativa. O manejo com gradagem apresentou produtividade significativamente maior em rela����o ao manejo com ro��ada.

PHOTOCATALYTIC OXIDATION OF AQUEOUS SOLUTIONS OF JET FUEL AND ICING INHIBITORS

The present paper is devoted to the results of experimental research undertaken into photocatalytical oxidation (PCO) of aqueous solutions of de-icing agents and aqueous extract of jet fuel. The report consists of introduction, literature review, description of materials and methods, discussion of results and conclusions. TiO2 was selected as a photocatalyst for the experiments with synthetic solutions of ethylene glycol, 2-ethoxyethanol and aqueous extract of jet fuel. To explain the PCO mechanisms affecting certain behaviour of de-icing agent under distinctive conditions, the following factors were studied: the impact of initial concentration of pollutant, the role of pH, the presence of tert-butanol as OH��-radicals scavenger and mineral admixtures. PCO under solar radiation performed in two ways: catalysed by irradiated TiO2 slurry or by TiO2 attached to buoyant hollow glass micro-spheres. Special attention was paid to the energy-saving PCO with reduced intensity mixing of the slurry. The effect of PCO was assessed by determination of residual chemical oxygen demand of solution (COD) and by measuring of concentration of glycols. The PCO process efficiency was assumed to be dependent on the TiO2 suspension fractional composition. Thus, the following effects of solutions��� media were viewed: presence of organic admixtures, pH influence, mixing mode during the PCO. The effects of mineral admixtures - Ca2+, Fe3+/2+, Mn2+, SO42- - that are often present in natural and wastewater systems or produced during the degradation of organic pollutants and which can affect the rate of PCO of de-icing agents, were also investigated.

Alikriittisen veden k��ytt�� kromatografisessa erotuksessa

Alikriittisell�� vedell�� tarkoitetaan paineistettua vett��, joka on kriittisen l��mp��tilansa (374 ��C) alapuolella nestem��isess�� tilassa. Veden tiheys pienenee l��mp��tilan kasvaessa Veden liuotinominaisuuksia voidaan s����dell�� l��mp��tilan avulla. Veden pintaj��nnitys, viskositeetti, tiheys ja polaarisuus pienenev��t l��mp��tilan kasvaessa, ja alikriittisen veden aineominaisuudet muuttuvat l��hemm��ksi orgaanista liuotinta. Alikriittisen veden dielektrisyysvakion aleneminen johtuu p����asiassa l��mp��tilan vaikutuksesta ja vain v��h��n paineen vaikutuksesta. Alikriittist�� vett�� on k��ytetty liuottimena uutossa, mutta nyt my��s alikriittinen kromatografia on kehittym��ss�� oleva erotusmenetelm��. Ty��n kokeellisessa osassa kehitettiin kromatografinen laitteisto alikriittiselle vedelle, jolla tutkittiin sokerialkoholien ja sokerien kromatografista erotusta alikriittisen veden avulla. Lis��ksi tutkittiin sokerialkoholien, sokereiden ja station����rifaasien termist�� kest��vyytt��. Tutkittavina komponentteina olivat sorbitoli, mannitoli, ksylitoli, arabinoosi, mannoosi, ksyloosi, maltoosi ja ramnoosi. Station����rifaaseina k��ytettiin makrohuokoista funktionalisoimatonta polystyreenidivinyylibentseenikopolymeeri��, sek�� vahvoja ja heikkoja divinyylibentseenill�� ristisilloitettuja kationinvaihtohartseja, jotka olivat joko Na+- tai Ca2+-ionimuodoissa. Veden l��mp��tilan nostaminen vaikuttaa sek�� kromatografisen station����rifaasin tilavuusmuutoksiin ett�� n��ytekomponenttien ominaisuuksiin. Vahvoilla kationinvaihtimilla havaittiin termisten tilavuusmuutosten riippuvan ionimuodosta: Na+-muotoiset hartsit turpoavat ja Ca2+-muotoiset kutistuvat l��mp��tilan noustessa. Heikot kationinvaihtimet kutistuvat molemmissa ionimuodoissa, mutta Ca2+-muoto kutistuu Na+-muotoa voimakkaammin. N��ytekomponenteista sokerialkoholien havaittiin kest��v��n paremmin korkeita l��mp��tiloja kuin sokerien. Sokerialkoholeista kest��vimm��ksi havaittiin ksylitoli ja sokereista ramnoosi. Tutkittavien komponenttien piikkien havaittiin kapenevan, h��ntimisen v��henev��n, ja piikkien eluoituvan aikaisemmin riippuen k��ytett��v��st�� station����rifaasista. Ca2+-muotoisen vahvan kationinvaihtimen kompleksinmuodostuskyky heikkeni l��mp��tilan kasvaessa. N��ytekomponenttien erotus ei kuitenkaan parantunut l��mp��tilan noustessa tutkituilla station����rifaaseilla.