Diapocynin versus apocynin as pretranscriptional inhibitors of NADPH oxidase and cytokine production by peripheral blood mononuclear cells

Apocynin has been extensively used as an inhibitor of NADPH oxidase (NOX) in many experimental models using phagocytic and non-phagocytic cells. Currently, there is some controversy about the efficacy of apocynin in non-phagocytic cells, but in phagocytes the reported results are consistent, which could be due to the presence of myeloperoxidase in these cells. This enzyme has been proposed as responsible for activating apocynin by generating its dimer, diapocynin, which is supposed to be the active compound that prevents NADPH oxidase complex assembly and activation. Here, we synthesized diapocynin and studied its effect on inhibition of gp91(phox) RNA expression. We found that diapocynin strongly inhibited the expression of gp91(phox)mRNA in peripheral blood mononuclear cells (PBMC). Only at a higher concentration, apocynin was able to exert the same effect. We also compared the apocynin and diapocynin efficacy as inhibitors of tumor necrosis factor-alpha (TNF-alpha) and interleukin-10 (IL-10) production in response to lipopolysaccharide (LPS)-activated PBMC. Although apocynin did inhibit TNF-alpha production, diapocynin had a much more pronounced effect, on both TNF-alpha and IL-10 production. In conclusion, these findings suggest that the bioconversion of apocynin to diapocynin is an important issue not limited to enzymatic activity inhibition, but also for other biological effects as gp91(phox) mRNA expression and cytokine production. Hence, as diapocynin can be easily prepared from apocynin, a one-step synthesis, we recommend its use in studies where the biological effects of apocynin are searched. (C) 2010 Elsevier Inc. All rights reserved.

Effects of aerobic exercise on the blood pressure, oxidative stress and eNOS gene polymorphism in pre-hypertensive older people

The polymorphisms of endothelial nitric oxide synthase (eNOS) are associated with reduced eNOS activity. Aerobic exercise training (AEX) may influence resting nitric oxide (NO) production, oxidative stress and blood pressure. The purpose of this study was to investigate the effect of AEX on the relationship among blood pressure, eNOS gene polymorphism and oxidative stress in pre-hypertensive older people. 118 pre-hypertensive subjects (59 +/- A 6 years) had blood samples collected after a 12 h overnight fast for assessing plasma NO metabolites (NOx) assays, thiobarbituric acid reactive substances (T-BARS) and superoxide dismutase activity (ecSOD). eNOS polymorphism (T-786C and G-894T) was done by standard PCR methods. All people were divided according to the genotype results (G1: TT/GG, G2: TT/GT + TT, G3: TC + CC/GG, G4: TC + CC/GT + TT). All parameters were measured before and after 6 months of AEX (70% of VO(2 max)). At baseline, no difference was found in systolic and diastolic blood pressure, ecSOD and T-BARS activity. Plasma NOx levels were significantly different between G1 (19 +/- A 1 mu M) and G4 (14.2 +/- A 0.6 mu M) and between G2 (20.1 +/- A 1.7 mu M) and G4 (14.2 +/- A 0.6 mu M). Therefore, reduced NOx concentration in G4 group occurred only when the polymorphisms were associated, suggesting that these results are more related to genetic factors than NO-scavenging effect. After AEX, the G4 increased NOx values (17.2 +/- A 1.2 mu M) and decreased blood pressure. G1, G3 and G4 decreased T-BARS levels. These results suggest the AEX can modulate the NOx concentration, eNOS activity and the relationship among eNOS gene polymorphism, oxidative stress and blood pressure especially in C (T-786C) and T (G-894T) allele carriers.

On the preparation of clean tungsten single crystals

The cleaning procedure consists of two-step-flashing: (i) cycles of low power flashes T similar to 1200 K) at an oxygen partial pressure of P(o2) = 6 x 10(-8) mbar, to remove the carbon from the surface, and (ii) a single high power flash (T similar to 2200 K), to remove the oxide layer. The removal of carbon from the surface through the chemical reaction with oxygen during low power flash cycles is monitored by thermal desorption spectroscopy. The exposure to O(2) leads to the oxidation of the W surface. Using a high power flash, the volatile W-oxides and the atomic oxygen are desorbed, leaving a clean crystal surface at the end of procedure. The method may also be used for cleaning other refractory metals like Mo, Re and It. (C) 2009 Elsevier B.V. All rights reserved.

Spectroscopic and theoretical studies of some N-methoxy-N-methyl-2-[(4 `-substituted) phenylthio]propanamides

The analysis of the IR carbonyl band of the N-methoxy-N-methyl-2-[(4`-substituted)phenylthio]propanamides Y-PhSCH(Me)C(O)N(OMe)Me (Y=OMe 1, Me 2, H 3, Cl 4, NO(2) 5), supported by B3LYP/cc-pVDZ calculations of 3, indicated the existence of two gauche conformers (g(1) and g(2)), the g(1) conformer being the more stable and the less polar one (in gas phase and in solution). Both conformers are present in solution of the polar solvents (CH(2)Cl(2) and CH(3)CN) for 1-5 and in solution of the less polar solvent (CHCl(3)) for 1-4, while only the g(1) conformer is present in solution of non polar solvents (n-C(6)H(14) and CCl(4)) and in solution of CHCl(3) for 5. NBO analysis shows that both the sigma(C-S) -> pi*(C=O) (hyperconjugative) and the pi(C=O) -> sigma*(C-S) orbital interactions contribute almost to the same extent for the stabilization of g(1) and g(2) conformers. The pi*(C=O) -> sigma*(C-S), n(S) -> pi*(C=O) and the n(S) -> pi*(C=O) orbital interactions stabilize more the g(1) conformer than the g(2) one. Moreover, the suitable geometry of the g(1) conformer leads to its stabilization through the LP(O2) -> sigma*(C8-H11) orbital interaction (hydrogen bond) along with the strong O([CO])(delta-) center dot center dot center dot H([O-Ph])(delta+) electrostatic interaction. On the other hand, the appropriate geometry of the g(2) conformer leads to its stabilization by the LP(O22) -> sigma*(C9-H13) orbital interaction (hydrogen bond) along with the weak O([OMe])(delta-) center dot center dot center dot H([o`-Ph])(delta+) electrostatic static interaction. As for the 4`-nitro derivative 5 the ortho-phenyl hydrogen atom becomes more acidic, leading to a stronger O([CO])(delta-) center dot center dot center dot H([o-Ph])(delta+) interaction and, thus, into a larger stabilization of the g(1) conformer in the whole series. This trend is responsible for the unique IR carbonyl band in CHCl(3) solution of 5. The larger occupancy of the pi*(C=O) orbital of the g(1) conformer relative to that of the g(2) conformer, along with the O([CO])(delta-) center dot center dot center dot H([o-Ph])(delta+) electrostatic interaction (hydrogen bond) justifies the lower carbonyl frequency of the g(1) conformer with respect to the g(2) one, in gas phase and in solution. (C) 2008 Elsevier B.V. All rights reserved.

Spectroscopic and theoretical studies of some 2-ethylsulfinyl-(4 `-substituted)-phenylthioacetates

The analysis of the IR nu(co) bands of the 2-ethylsulfinyl-(4`-substituted)-phenylthioacetates 4`-Y-C(6)H(4)SC(O)CH(2)S(O)Et (Y = NO(2) 1, Cl 2, Br 3, H 4, Me 5, OMe 6) supported by B3LY/6-31G(d,p) calculations along with the NBO analysis for 1.4 and 6 and X-ray analysis for 3, indicated the existence of four gauche (q-g-syn, g(3)-syn. g(1)-atin and q-g(2)-syn) conformers for 1-6 The calculations reproduce quite well the experimental results, i e the computed q-g-syn and g3-syn conformers correspond in the IR spectrum (in solution), to the nu(co) doublet higher frequency component of larger intensity, while the computed grant, conformer correspond to the nu(co) doublet lower frequency component (in solution) NBO analysis showed that the n(s) -> pi(center dot)(c1=o2), no(co) -> sigma(c1-s3), no(co) -> sigma(c1-c4) orbital interactions are the main factors which stabilize the q-g-syn, g(3)-syn, g(1)-anti and q-g(2)-syn conformers for 1, 4 and 6 The no(co) -> sigma(c1-s3) interaction which stabilizes the q-g-syn, g(3)-syn and q-g(2)-syn conformers into a larger extent than the granti conformer, is responsible for the larger tto frequencies of the former conformers relative to the latter one. The q-g-syn, g(3)-syn and q-g(2)-syn conformers are further stabilized sigma(c4-s5) -> pi(co)center dot (strong). pi(co)/sigma(c1-c4,) no(co) -> sigma(c6-H17[Et]) (weak) and pi(co)/sigma(c4-c5) pi(co) (strong) orbital interactions. The q-g-syn conformer is also stabilized by sigma(c4-s5) -> pi(center dot)(co) (strong), pi(co)/sigma(c4-c5).no(co) -> sigma(c6-H17[Et]), pi(C9=C11[ph]) -> sigma(c4-H6x-CH2]) (weak). no((SO)) -> sigma(C11-H23[ph]) (medium) pi(co)/sigma(c4-c5)(strong) orbital interactions. The q-g-syn conformei is further stabilized by the n(S5) O((C))(8-) S((SO))(8+) attractive Coulornbic interaction while the q-g(2)-syn conformer is destabilized by the n55 0,8c-0) repulsive Coulombic interaction. This analysis indicates the following conformer stabilization order. q-g-syn, g(3)-syn > g(1)-anti >> q-g(2)-syn X-ray single crystal analysis of 3 indicates that it assumes in the solid a distorted q-g(2)-syn geometry which is stabilized through almost the same orbital and Coulombic interaction which takes place for the q-g(2)-syn conformer, in the gas, along with dipole moment coupling and a series intermolecular C-HO0 interactions. (C) 2010 Elsevier B V All rights reserved

M��tning och utv��rdering av PM br��nnaren

The PM-brännaren (pellets burner) have on commission by the company been measured and evaluated in the combustion laboratory of SERC. The objective was to measure the perform-ance and the emissions of CO and NO for three different combustion powers and for start and stop conditions. The burner have been mounted in the Bionett-boiler from Ariterm and been adjusted by the company. The boiler has been connected to a buffer store that admits firing during long period with constant inlet temperature to the boiler. The measurements have been performed by operating the boiler on constant power until stationary conditions are reached. Thereafter the following two hours of operation have been evaluated. The results show that the burner fulfils the limit values for Blauer Engel labelling and the proposed limit values for Nordic Eco labelling. The measured concentration of NO is far below all organisations limit values for NOx. Concerning the start and stop emissions there are no demands from organisa-tions to compare with, but comparing with other boilers measured at SERC, the CO emissions from PM-brännaren is in the same order of magnitude.

An Experimental Study of Submerged Entry Nozzles (SEN) Focusing on Decarburization and Clogging

The submerged entry nozzle (SEN) is used to transport the molten steel from a tundish to a mould. The main purpose of its usage is to prevent oxygen and nitrogen pick-up by molten steel from the gas. Furthermore, to achieve the desired flow conditions in the mould. Therefore, the SEN can be considered as a vital factor for a stable casting process and the steel quality. In addition, the steelmaking processes occur at high temperatures around 1873 K, so the interaction between the refractory materials of the SEN and molten steel is unavoidable. Therefore, the knowledge of the SEN behaviors during preheating and casting processes is necessary for the design of the steelmaking processes�� The internal surfaces of modern SENs are coated with a glass/silicon powder layer to prevent the SEN graphite oxidation during preheating. The effects of the interaction between the coating layer and the SEN base refractory materials on clogging were studied. A large number of accretion samples formed inside alumina-graphite clogged SENs were examined using FEG-SEM-EDS and Feature analysis. The internal coated SENs were used for continuous casting of stainless steel grades alloyed with Rare Earth Metals (REM). The post-mortem study results clearly revealed the formation of a multi-layer accretion. A harmful effect of the SENs decarburization on the accretion thickness was also indicated. In addition, the results indicated a penetration of the formed alkaline-rich glaze into the alumina-graphite base refractory. More specifically, the alkaline-rich glaze reacts with graphite to form a carbon monoxide gas. Thereafter, dissociation of CO at the interface between SEN and molten metal takes place. This leads to reoxidation of dissolved alloying elements such as REM (Rare Earth Metal). This reoxidation forms the ���In Situ��� REM oxides at the interface between the SEN and the REM alloyed molten steel. Also, the interaction of the penetrated glaze with alumina in the SEN base refractory materials leads to the formation of a high-viscous alumina-rich glaze during the SEN preheating process. This, in turn, creates a very uneven surface at the SEN internal surface. Furthermore, these uneven areas react with dissolved REM in molten steel to form REM aluminates, REM silicates and REM alumina-silicates. The formation of the large ���in-situ��� REM oxides and the reaction of the REM alloying elements with the previously mentioned SEN��s uneven areas may provide a large REM-rich surface in contact with the primary inclusions in molten steel. This may facilitate the attraction and agglomeration of the primary REM oxide inclusions on the SEN internal surface and thereafter the clogging. The study revealed the disadvantages of the glass/silicon powder coating applications and the SEN decarburization. The decarburization behaviors of Al2O3-C, ZrO2-C and MgO-C refractory materials from a commercial Submerged Entry Nozzle (SEN), were also investigated for different gas atmospheres consisting of CO2, O2 and Ar. The gas ratio values were kept the same as it is in a propane combustion flue gas at different Air-Fuel-Ratio (AFR) values for both Air-Fuel and Oxygen-Fuel combustion systems. Laboratory experiments were carried out under nonisothermal conditions followed by isothermal heating. The decarburization ratio (��) values of all three refractory types were determined by measuring the real time weight losses of the samples. The results showed the higher decarburization ratio (��) values increasing for MgO-C refractory when changing the Air-Fuel combustion to Oxygen-Fuel combustion at the same AFR value. It substantiates the SEN preheating advantage at higher temperatures for shorter holding times compared to heating at lower temperatures during longer holding times for Al2O3-C samples. Diffusion models were proposed for estimation of the decarburization rate of an Al2O3-C refractory in the SEN. Two different methods were studied to prevent the SEN decarburization during preheating: The effect of an ZrSi2 antioxidant and the coexistence of an antioxidant additive and a (4B2O3 ��BaO) glass powder on carbon oxidation for non-isothermal and isothermal heating conditions in a controlled atmosphere. The coexistence of 8 wt% ZrSi2 and 15 wt% (4B2O3 ��BaO) glass powder of the total alumina-graphite refractory base materials, presented the most effective resistance to carbon oxidation. The 121% volume expansion due to the Zircon formation during heating and filling up the open pores by a (4B2O3 ��BaO) glaze during the green body sintering led to an excellent carbon oxidation resistance. The effects of the plasma spray-PVD coating of the Yttria Stabilized Zirconia (YSZ) powder on the carbon oxidation of the Al2O3-C coated samples were investigated. Trials were performed at non-isothermal heating conditions in a controlled atmosphere. Also, the applied temperature profile for the laboratory trials were defined based on the industrial preheating trials. The controlled atmospheres consisted of CO2, O2 and Ar. The thicknesses of the decarburized layers were measured and examined using light optic microscopy, FEG-SEM and EDS. A 250-290 ��m YSZ coating is suggested to be an appropriate coating, as it provides both an even surface as well as prevention of the decarburization even during heating in air. In addition, the interactions between the YSZ coated alumina-graphite refractory base materials in contact with a cerium alloyed molten stainless steel were surveyed. The YSZ coating provided a total prevention of the alumina reduction by cerium. Therefore, the prevention of the first clogging product formed on the surface of the SEN refractory base materials. Therefore, the YSZ plasma-PVD coating can be recommended for coating of the hot surface of the commercial SENs.

Emissions Characterisation of residential pellet boilers during start-up and stop periods

In this study, gaseous emissions and particles are measured during start-up and stop periods for an over-fed boiler and an under-fed boiler. Both gaseous and particulate matter emissions are continuously measured in the laboratory. The measurement of gaseous emissions includes oxygen (O2), carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxide and (NO). The emissions rates are calculated from measured emissions concentrations and flue gas flow. The behaviours of the boilers during start-up and stop periods are analysed and the emissions are characterised in terms of CO, NO, TOC and particles (PM2.5 mass and number). The duration of the characterised periods vary between two boilers due to the difference in type of ignition and combustion control. The under-fed boiler B produces higher emissions during start-up periods than the over-fed boiler A. More hydrocarbon and particles are emitted by the under-fed boiler during stop periods. Accumulated mass of CO and TOC during start-up and stop periods contribute a major portion of the total mass emitted during whole operation. However, accumulated mass of NO and PM during start-up and stop periods are not significant as the duration of emission peak is relatively short.

Photochemical Production of MicromolarSuperoxideStandards in Aqueous SolutionT

Superoxide(O2-) is a reactive free radical that rapidly undergoes disproportionation to hydrogen peroxide and oxygen. This property makes preparation of superoxide standard for instrument calibration difficult. McDowell et al. (1983) showed photolysis of ketone and alcohol as a convenient method to generate superoxide through triplet and radical intermediates reacting with molecular oxygen. This study expands on this past work and investigates detailed mechanism of the reaction.

Contribui����o ao estudo da inibi����o da corros��o do a��o comum por borato, em solu����es dilu��das

Este trabalho teve por objetivo determinar a a����o inibidora do ��on borato na corros��o do a��o-carbono, em solu����es aquosas aproximadamente neutras, arejadas e desarejadas, na presen��a ou n��o de ions cloreto, �� temperatura ambiente. Atrav��s do tra��ado de curvas de polariza����o potenciost��ticas, de experimentos cronopotenciom��tricos e cronogalvanom��tricos, com ou sem riscagem do corpo de prova, e do comportamento do a��o comum em ensaios de imers��o a longo prazo, concluiu-se que o ion borato possui uma a����o inibidora sobre a corros��o do a��o, desde que o potencial n��o seja muito elevado. Observou-se tamb��m que o a��o sofre corros��o por pites em solu����es de borato, mesmo na aus��ncia de ��ons agressivos e que os pites ocorrem em potenciais tanto mais baixos quanto mais dilu��das forem as solu����es de borato. Para solu����es contendo 1000 ppm de b��rax ou mais, o potencial de pite, determinado por t��cnicas cronopotenciom��tricas, est�� acima do potencial de corros��o. Para solu����es com concentra����es iguais ou superiores a 5000 ppm de b��rax, n��o foi detectada corros��o por pites na faixa de potencial estudada, isto ��, desde o potencial de evolu����o de H2 at�� o potencial de evolu����o de 02. A adi����o de 100 ppm de NaCl �� solu����o contendo 2500 ppm de b��rax reduz o potencial de pite de a��o comum, em rela����o ao seu valor na aus��ncia de ��on cloreto.

Rea����es de oxida����o de ��lcoois e olefinas promovidas por complexos de metais de transi����o imobilizados em l��quidos i��nicos fluorados

Neste trabalho foi estudada a viabilidade da transposi����o direta de rea����es de oxida����o efetuadas em meio homog��neo ou meio bif��sico aquoso para meio bif��sico onde l��quidos i��nicos s��o empregados como agentes imobilizadores dos catalisadores utilizados. A oxida����o de ��lcoois secund��rios (ciclopentanol) e de ��lcoois prim��rios ativados (��lcool benz��lico) mostrou-se mais efetiva quando 1 mol% de RuCl3 imobilizados no l��quido i��nico tetrafluoroborato de 1-n-butil-3-metilimidaz��lio (BMI.BF4), 100 ��C de temperatura, 7 atm de oxig��nio e 24 horas de rea����o foram empregados, levando a 61% de convers��o, 100% de seletividade em ciclopentanona e freq����ncia de rota����o 2,54 h-1 (com peneira molecular no solvente) e 86% de convers��o, 95% de seletividade em benzalde��do e freq����ncia de rota����o 3,58 h-1. Estes resultados s��o superiores aos obtidos em condi����es homog��neas. Quando o l��quido i��nico BMI.BF4 foi substitu��do por l��quidos i��nicos fluorados, tais como BMI.OOCCF3 e o novo l��quido i��nico BMI.OOC(CF2)6CF3 a convers��o dobrou e a seletividade se manteve em 100%, nas condi����es estudadas. A oxida����o de olefinas (1-deceno) catalisada por PdCl2/CuCl2/O2 apresentou melhores resultados quando 2 mol% de PdCl2 e 4 mol% de CuCl2 foram imobilizados no l��quido i��nico BMI.BF4 a 80 ��C de temperatura, 6 atm de oxig��nio e 16 horas de rea����o foram empregados, levando a 99% de convers��o, 53% de seletividade em 2-decanona e freq����ncia de rota����o 3,09 h-1. Quando o sistema catal��tico foi reutilizado a convers��o foi de 88% e a seletividade 60%.

Simula����o num��rica de escoamentos hipers��nicos em n��o-equil��brio termo-qu��mico atrav��s do m��todo dos elementos finitos

o presente trabalho tem por objetivo desenvolver um c��digo computacional destinado �� simula����o num��rica tridimensional e de escoamentos compress��veis hipers��nicos em especial para analisar o processo de reentrada de ve��culos espaciais na atmosfera terrestre. Devido ��s temperaturas elevadas encontradas neste tipo de escoamento, efeitos de altas temperaturas s��o inclu��dos, como excita����o vibracional das mol��culas e rea����es qu��m��cas. Utiliza-se o modelo de 2 temperaturas (translacional e vibracional);5 esp��c��es (N2, O2, NO, N, O) e 17 rea����es qu��micas de Park [1986 para o modelamento do fen��meno termo-qu��mico. Introduz-se uma formula����o baseada no m��todo dos elementos finitos, atrav��s do esquema de Taylor-Calerkin, para a discretiza����o do tempo e do espa��o e para a solu����o do sistema de equa����es. Alguns exemplos e aplica����es de problemas hipers��nicos bi e tridimensionais, difusivos e n��o difusivos, s��o apresentados, incluindo compara����es entre os resultados obtidos no presente trabalho e na literatura.

Influ��ncia do hipotireoidismo no dano oxidativo e nas defesas antioxidantes

O hipotireoidismo �� uma doen��a que tem grande impacto sobre o metabolismo basal dos tecidos, reduzindo o consumo de O2 e gera����o de energia. Por essa raz��o, a sua rela����o com a produ����o de esp��cies ativas de oxig��nio (EAO) �� extremamente importante, uma vez que com a diminui����o da utiliza����o de O2, possivelmente, ocorra uma redu����o na gera����o das EAO. Portanto, trabalhamos com a hip��tese de que havendo decr��scimo na s��ntese de radicais livres, o dano oxidativo ficaria menos evidente nos diferentes tecidos de hipotireoideos. Foram utilizados ratos Wistar, pesando cerca de 170 g divididos em dois grupos distintos: hipotireoideos e eutireoideos. O hipotireoidismo foi induzido pelo procedimento cir��rgico denominado de tireoidectomia. Cabe salientar, que os animais eutireoideos foram submetidos somente �� simula����o da cirurgia (sham operated). Transcorridas quatro semanas da tireoidectomia, os ratos tiveram seu sangue coletado e seus ��rg��os (cora����o e f��gado) removidos. Foram feitas an��lises bioqu��micas do dano oxidativo atrav��s da medida da lipoperoxida����o (TBA-RS e Quimiluminesc��ncia) e da oxida����o das prote��nas (dosagem das carbonilas). Medidas de defesas antioxidantes enzim��ticas (atividade e concentra����o das enzimas catalase, super��xido dismutase, glutationa peroxidase e glutationa���S���transferase) e n��o enzim��ticas (atrav��s da medida da capacidade antioxidante total -TRAP) tamb��m foram realizadas. Os resultados, da quantifica����o da lipoperoxida����o, demonstraram a diminui����o das cifras de TBA-RS e Quimiluminesc��ncia no sangue e tecido card��aco dos ratos tireoidectomizados em rela����o ao grupo eutireoideo. No entanto, no tecido hep��tico n��o houve altera����o deste par��metro. A oxida����o das prote��nas tamb��m foi menor no plasma dos animais hipotireoideos. Por outro lado, o TRAP e a atividade das enzimas antioxidantes se apresentaram em decl��nio no grupo hipotireoideo em rela����o ao grupo eutireoideo, no mioc��rdio e nos eritr��citos. Todavia, no tecido hep��tico, somente a catalase demonstrou decr��scimo da atividade catal��tica nos hipotireoideos. As concentra����es das enzimas antioxidantes super��xido dismutase e glutationa���S���transferase, medidas por Western Blott, foram menores no cora����o e sangue, e inalteradas no f��gado. Esses resultados sugerem que o estado hipometab��lico, causado pela defici��ncia dos horm��nios da tire��ide, pode levar �� redu����o dos danos oxidativos aos lip��deos e ��s prote��nas. Entretanto, n��o podemos afirmar que o estresse oxidativo dos animais hipotireoideos seja inferior aos eutireoideos, porque as defesas antioxidantes tamb��m est��o reduzidas nestes animais.

Avalia����o da genotoxicidade induzida por emiss��es de ve��culos automotores - Ctenomys minutus como organismo bioindicador

Existe um n��mero crescente de componentes qu��micos lan��ados ao meio ambiente, muitos dos quais s��o capazes de induzir efeitos danosos adversos �� sa��de de animais e humanos, representando uma causa importante de preocupa����o por seus poss��veis efeitos a longo prazo. O impacto ecol��gico e os riscos a sa��de dos organismos associados com a exposi����o a poluentes ambientais s��o extremamente dif��ceis de se avaliar devido a muitos desses componentes serem parte de misturas complexas. Os gases produzidos pelos motores dos ve��culos �� combust��o cont��m diversos poluentes sabidamente genot��xicos, como ��xidos de nitrog��nio (NOX), mon��xido de carbono (CO), ��xidos de enxofre (SOx), hidrocarbonetos (HC) e seus derivados, bem como particulados, e metais (c��dmio, cromo, cobre, n��quel, van��dio, zinco e chumbo). Todos esses compostos isolados ou associados a outros elementos s��o t��xicos ou de efeito danoso aos organismos, de forma n��o totalmente esclarecida. Este estudo teve como objetivo verificar o poss��vel efeito genot��xico das emiss��es dos autom��veis em roedor nativo Ctenomys minutus cronicamente exposto, atrav��s do Ensaio Cometa (EC), comparando os resultados com o Teste de Micron��cleos (MN), ambos em sangue perif��rico. Levando em considera����o alguns fatores que pudessem influenciar os resultados dos testes de genotoxicidade, este trabalho ainda teve como objetivos: identificar a presen��a de alguns agentes envolvidos na polui����o gerada pelos ve��culos; verificar poss��veis diferen��as sazonais, como temperatura e ventos; e se existe influ��ncia da idade e sexo dos roedores. Os C. minutus (Octodontidae-Rodentia), foram capturados em dois campos diferentes, ambos ao lado da estrada RS/030, na cidade de Os��rio, Estado do Rio Grande do Sul (RS): (a) Amaral, e (b) Weber. Animais para controle externo foram capturados no Campo Maribo �� cerca de 3 km de dist��ncia de outra estrada (RS/389-Os��rio/RS), conseq��entemente afastada das emiss��es dos ve��culos. No final do per��odo desse estudo, foram capturados 123 animais (73 f��meas e 50 machos).

Filmes finos diel��tricos para dispositivos microeletr��nicos avan��ados

Apresentamos mecanismos de forma����o e de degrada����o t��rmica de filmes fi- nos (espessura da ordem de 10 nm) de diferentes diel��tricos sobre substrato de sil��cio monocristalino. Tendo em vista a aplica����o dessas estruturas em MOSFETs (transistores de efeito de campo metal-��xido-semicondutor), estudamos o consagrado ��xido de sil��cio (SiO2), os atuais substitutos oxinitretos de sil��cio (SiOxNy) e o poss��vel substituto futuro ��xido de alum��nio (Al2O3). Nossos resultados experimentais baseiam-se em t��cnicas preparativas de substitui����o isot��pica e de caracteriza����o f��sica com feixes de ��ons (an��lise com rea����es nucleares) ou raios- X (espectroscopia de fotoel��trons). Observamos que: (a) ��tomos de sil��cio n��o apresentam difus��o de longo alcance (al��m de ~ 2 nm) durante o crescimento de SiO2 por oxida����o t��rmica do sil��cio em O2; (b) nitreta����o hipert��rmica �� capaz de produzir filmes finos de oxinitreto de sil��cio com at�� dez vezes mais nitrog��nio que o resultante do processamento t��rmico usual, sendo que esse nitrog��nio tende a se acumular na interface SiOxNy/Si; e (c) ��tomos de oxig��nio, alum��nio e sil��cio migram e promovem rea����es qu��micas durante o recozimento t��rmico de estruturas Al2O3/SiO2/Si em presen��a de O2. Desenvolvemos um modelo de difus��o-rea����o que poder�� vir a permitir o estabelecimento de condi����es ��timas de processamento t��rmico para filmes finos de Al2O3 sobre sil��cio a serem empregados na fabrica����o de MOSFETs.