Showing papers by "State University of Campinas published in 1997"

Photocatalytic destruction of VOCs in the gas-phase using titanium dioxide

Abstract: The gas-phase photocatalytic destruction of 17 VOCs over illuminated titanium dioxide was investigated using a plug flow reactor with the following experimental conditions: 200 ml min−1 flow rate, 23% relative humidity, 21% oxygen and an organic compound concentration range of 400–600 ppmv. At steady state, high conversion yields were obtained for trichloroethylene (99.9%), isooctane (98.9%), acetone (98.5%), methanol (97.9%), methyl ethyl ketone (97.1%),t-butyl methyl ether (96.1%), dimethoxymethane (93.9%), methylene chloride (90.4%), methyl isopropyl ketone (88.5%), isopropanol (79.7%), chloroform (69.5%) and tetrachloroethylene (66.6%). However, the photodegradation of isopropylbenzene (30.3%), methyl chloroform (20.5%) and pyridine (15.8%) was not so efficient. Carbon tetrachloride photoreduction was investigated in the presence of methanol as an electron donor. It was observed that the presence of methanol results in higher degradation rates. No reaction byproducts were detected for all VOCs tested under the experimental set-up and conditions described. Also, long-term conversion was obtained for all tested compounds. Catalyst deactivation was detected with toluene only, but the activity was restored by illuminating the catalyst in the presence of hydrogen peroxide. The capacity of the process to destroy different classes of volatile organic compounds present in the atmosphere was demonstrated.

Ischemic lesion volumes in acute stroke by diffusion-weighted magnetic resonance imaging correlate with clinical outcome.

Abstract: Diffusion-weighted magnetic resonance imaging detects ischemic injury within minutes after onset, and has been used to demonstrate drug efficacy in animal models of stroke. In 50 patients diagnosed with acute ischemic stroke (<24-hour duration) within the middle cerebral artery territory, lesion volume was measured by diffusion-weighted imaging. Thirty-four patients also had volumes measured by T2-weighted imaging chronically (median time, 7.5 weeks; mean, 15.9 weeks). Clinical severity was measured by the National Institutes of Health Stroke Scale Score and the Barthel index. Acute lesion volumes correlated with the acute stroke scale score (r = 0.56), the chronic stroke scale score (r = 0.63), and chronic lesion volumes (r = 0.84). Chronic volumes correlated with the chronic stroke scale score (r = 0.86) and the Barthel index (r = -0.60). When only cortically based lesions were considered, the correlations relating acute lesion volume measured by diffusion-weighted imaging (r = 0.61) and chronic lesion volume measured by T2-weighted imaging (r = 0.90) to the chronic stroke scale score were higher. These results provide evidence that lesion volumes determined by diffusion-weighted imaging acutely may be predictive of clinical severity and outcome, and may support a role for diffusion-weighted imaging in the assessment of acute stroke therapies in clinical trials.

Comparison of Spray‐drying, Drum‐drying and Freeze‐drying for β‐Carotene Encapsulation and Preservation

Abstract: Pure β-carotene was encapsulated in 25 Dextrose Equivalent maltodextrin by three drying processes (spray, freeze and drum) Stability was studied at 11% and 32% RH and 25°C, 35°C and 45°C No significant influence of %RH was observed on the retention of β-carotene Oxidation followed first order kinetics with an initial fast first order reaction followed by a second much slower first order reaction period Although drum-drying caused more initial loss in drying, the lower surface carotenoids and larger particle size resulted in greater stability as compared to the other methods The chromametric measurements of “L” and “a” corresponded to the other kinetics and indicated that the first period rapid loss corresponded to the oxidation of surface carotenoids

Oxidative Transformations of Organic Compounds Mediated by Redox Molecular Sieves

Abstract: Zeolites are viewed by some as the “philosopher's stone” of modern chemistry.[1] They are more or less indispensable in oil refining and petrochemicals manufacture where they are widely applied as solid acid catalysts. More recently attention has been focused on their use in the manufacture of fine chemicals. The synthetic utility of zeolites and related molecular sieves (zeotypes) has been considerably extended by the incorporation of redox metals into their frameworks. The resulting redox molecular sieves catalyze a variety of selective oxidations under mild conditions in the liquid phase. Their structural diversity–including variation of the redox metal, incorporation of metal complexes, and the size and polarity of the micropores–provides the possibility of designing tailor-made solid catalysts (“mineral enzymes”) for liquid-phase oxidations with clean oxidants such as O2, H2O2, and RO2H. Hence, they have enormous potential in industrial organic synthesis as environmentally friendly alternatives to traditional oxidations employing inorganic oxidants in stoichiometric amounts. A primary aim of this review is to familiarize organic chemists with the synthetic potential of redox molecular sieves. An outline of their synthesis, structures, and chemical properties, highlighting their unique advantages, is followed by a discussion of general (mechanistic) features that influence the choice of a suitable catalyst for a particular type of oxidation. The main part of the review deals with the oxidation of various substrates of synthetic interest–such as alkanes, alkenes, (alkyl)arenes, alcohols, and amines–and emphasizes the advantages of redox molecular sieves (including selectivity and stability) over their homogeneous counterparts. New directions towards truly biomimetic solid catalysts, for example zeolite-encapsulated chiral metal complexes as heterogeneous catalysts for asymmetric oxidations, are high-lighted.

The role of reactive oxygen species in mitochondrial permeability transition

Abstract: We have provided evidence that mitochondrial membrane permeability transition induced by inorganic phosphate, uncouplers or prooxidants such as t-butyl hydroperoxide and diamide is caused by a Ca2+-stimulated production of reactive oxygen species (ROS) by the respiratory chain, at the level of the coenzyme Q. The ROS attack to membrane protein thiols produces cross-linkage reactions, that may open membrane pores upon Ca2+ binding. Studies with submitochondrial particles have demonstrated that the binding of Ca2+ to these particles (possibly to cardiolipin) induces lipid lateral phase separation detected by electron paramagnetic resonance experiments exploying stearic acids spin labels. This condition leads to a disorganization of respiratory chain components, favoring ROS production and consequent protein and lipid oxidation.

The mutation Ala677-->Val in the methylene tetrahydrofolate reductase gene: a risk factor for arterial disease and venous thrombosis.

Abstract: Mild hyperhomocysteinemia has been identified as a risk factor for arterial disease and for venous thrombosis. Individuals homozygous for the thermolabile variant of the methylene tetrahydrofolate reductase gene (MTHFR) which results from a common mutation Ala677-->Val and is found in 5-15% of the general population, have significantly elevated plasma homocysteine levels and may account for one of the genetic risk factors in vascular disease. We have analyzed the prevalence of MTHFR-T homozygotes in patients with arterial disease or venous thrombosis. We studied 191 patients with arterial disease and 127 individuals with venous thrombosis and compared with 296 unmatched controls. The results showed that there was a high prevalence of homozygotes for the mutated MTHFR-T allele among a group of patients with arterial disease (19%) in the absence of hyperlipoproteinemia, hypertension, and diabetes mellitus when compared to controls (4%), odds ratio of 5.52 (95% C.I., 2.27 to 13.51). The prevalence of homozygotes among patients with venous thrombosis was 11%, odds ratio of 2l93 (95% C.I., 1.23 to 7.01). The risk of venous thrombosis remained high, odds ratio of 2.63, even after we excluded 27 patients with hereditary thrombophilia (e.g. factor V Leiden, dysfibrinogenemia, deficiency of protein C, protein S, antithrombin III, or factor XII) from the 127 overall cases with venous thrombosis. These data support the hypothesis that being a homozygote for the MTHFR-T is a risk factor for the development of arterial disease and also for venous thrombosis.

The Mutation Ala677 → Val In The Methylene Tetrahydrofolate Reductase Gene: A Risk Factor For Arterial Disease And Venous Thrombosis

Abstract: Mild hyperhomocysteinemia has been identified as a risk factor for arterial disease and for venous thrombosis. Individuals homozygous for the thermolabile variant of the methylene tetrahydrofolate reductase gene (MTHFR) which results from a common mutation Ala677-->Val and is found in 5-15% of the general population, have significantly elevated plasma homocysteine levels and may account for one of the genetic risk factors in vascular disease. We have analyzed the prevalence of MTHFR-T homozygotes in patients with arterial disease or venous thrombosis. We studied 191 patients with arterial disease and 127 individuals with venous thrombosis and compared with 296 unmatched controls. The results showed that there was a high prevalence of homozygotes for the mutated MTHFR-T allele among a group of patients with arterial disease (19%) in the absence of hyperlipoproteinemia, hypertension, and diabetes mellitus when compared to controls (4%), odds ratio of 5.52 (95% C.I., 2.27 to 13.51). The prevalence of homozygotes among patients with venous thrombosis was 11%, odds ratio of 2l93 (95% C.I., 1.23 to 7.01). The risk of venous thrombosis remained high, odds ratio of 2.63, even after we excluded 27 patients with hereditary thrombophilia (e.g. factor V Leiden, dysfibrinogenemia, deficiency of protein C, protein S, antithrombin III, or factor XII) from the 127 overall cases with venous thrombosis. These data support the hypothesis that being a homozygote for the MTHFR-T is a risk factor for the development of arterial disease and also for venous thrombosis.

Effects of aging on the circadian rhythm of wheel-running activity in C57BL/6 mice

Abstract: The effects of age on the circadian clock system have been extensively studied, mainly in two rodent species, the laboratory rat and the golden hamster. However, less information is available on ho...

NO·–releasing substances that induce growth elongation in maize root segments

Abstract: Root segments of maize were incubated in different solutions containing substances that non-enzymatically release nitric oxide, such as sodium nitrite (SN), sodium nitroprusside (SNP), nitrosoglutathione (NGLU) and nitrosocysteine (NCYS). We found that all of these substances induced root tip expansion in a dose-dependent manner. The decreasing order of potency for root-induced elongation was: 10 -7 M SN, pH 4.5; 10 -11 M NCYS, 10 -10 M SNP, 10 -9 M NGLU and 10 -7 M SN, pH 7.0. Nitric oxide scavenger such as methylene blue prevented the elongation induced by NO·–releasing substances, but had no effect on indole-3-acetic acid (IAA)-induced cell expansion. Our results suggest that nitric oxide is the putative elongation inducer and that IAA and NO·–releasing substances conceivably share common steps in the signal transduction pathway, since both elicited the same plant response. Vanadate, a plasmamembrane ATPase inhibitor, significantly reversed IAA-induced elongation when supplied at 10 μM concentration. IAA-induced elongation was strongly enhanced by 10 nM BAY K 8644, an agonist of voltage dependent Ca2+ channels. Promotion of root elongation in the absence of IAA occurred only at higher concentrations of BAY K. Vanadate and BAY K had no influence on the NCYS-induced elongation suggesting that the common steps in the signalling of IAA and NCYS are not at the level of the plasmamembrane.

The ecological function of extrafloral nectaries : herbivore deterrence by visiting ants and reproductive output in Caryocar brasiliense (Caryocaraceae)

Abstract: 1. Shrubs of Caryocar brasiliense are intensively visited by many ant species in the cerrado vegetation of south-east Brazil. Ants collect nectar from the extrafloral nectaries (EFNs) located on the buds at the apex of the plant. 2. The proportion of C. brasiliense shrubs occupied by ants greatly surpassed that of neighbouring plants without EFNs and this resulted in many more termites being attacked and removed on this plant than on plants lacking EFNs. Ant attacks on Caryocar were more frequent near the EFNs. 3. Ant-exclusion experiments with Caryocar shrubs revealed that ants significantly reduce the infestation levels by the butterfly Eunica bechina, the sucking bud Edessa rufomarginata, the bud-destroying fly Prodiplosis floricola and by a stem-galling wasp. Ants had no effect on the infestation by a leaf-galling wasp. 4. Control (ants present) and treatment (ants excluded) plants produced equal numbers of buds but flower and initial fruit production was significantly greater for ant-visited plants. Higher abortion rates of initial fruits by control plants resulted in similar final fruit and seed sets for plants in either experimental category. 5. The extremely low fertility of cerrado soils is suggested as a possible factor constraining the ability of Caryocar shrubs to provide the resources necessary for growth and development of their heavy fleshy fruits. Higher production of initial fruits by ant-visited shrubs would be neutralized by competition among developing fruits and subsequent abortion. 6. Possible ant-derived benefits to C. brasiliense include: protection of vegetative tissues during plant growth, larger floral display and increased attractiveness to bat pollinators, increased male contribution to fitness through pollen donation and selective abortion of genetically inferior progeny as the maternal investment is adjusted to match available resources.

Prevalence of the prothrombin gene variant (nt20210A) in venous thrombosis and arterial disease.

Abstract: The prothrombin gene variant resulting form a G >A transition at position 20210 has been described as a common genetic risk factor for venous thrombosis. However. the risk for developing arterial disease is unknown. In this investigation, we studied 116 patients with venous thrombosis and 71 with arterial disease, all of whom were compared with 295 controls. Additionally, we also investigated the distribution of the prothrombin alleles among African descendents and Amazonian Indians from Brazil. The prevalence of 0.7% for 20210A allele in the control group increased to 4.3% (P = 0.021) among patients with venous thrombosis. There was also a high prevalence of the mutated allele in a selected arterial disease group (5.7%) without hyperlipo-proteinemia, hypertension. and diabetes mellitus when compared to the controls (P = 0.013). Heterozygotes for the allele 20210A were common among individuals of African descent (2%) and rare among Indians. These data support the hypothesis that the prothrombin variant is a risk factor for venous thrombosis and suggest that it may also be a risk factor for arterial disease.

Magneto ‐ Micropolar Fluid Motion: Existence and Uniqueness of Strong Solution

Abstract: By using the spectral Galerkin method, we prove the existence and uniqueness of strong solutions for magneto - micropolar fluid motion.

Estimation of crowd density using image processing

Abstract: Human beings perceive images through their properties, like colour, shape, size, and texture. Texture is a fertile source of information about the physical environment. Images of low density crowds tend to present coarse textures, while images of dense crowds tend to present fine textures. The paper describes a technique for automatic estimation of crowd density, which is a part of the problem of automatic crowd monitoring, using texture information based on grey level transition probabilities on digitised images. Crowd density feature vectors are extracted from such images and used by a self organising neural network which is responsible for the crowd density estimation. Results obtained respectively to the estimation of the number of people in a specific area of Liverpool Street Railway Station in London (UK) are presented.

Genetic distance of inbred lines and prediction of maize single-cross performance using RAPD markers

Abstract: To evaluate the genetic diversity of 18 maize inbred lines, and to determine the correlation between genetic distance and single-cross hybrid performance, we have used random amplified polymorphic DNA (RAPD), a PCR-based technique. Eight of these lines came from a Thai synthetic population (BR-105), and the others derived from a Brazilian composite population (BR-106). Thirty two different primers were used giving a total of 325 reproducible amplification products, 262 of them being polymorphic. Genetic divergence was determinated using Jaccard’s similarity coefficient, and a final dendrogram was constructed using an unweighted pair-group method with arithmetical averages (UPGMA). Cluster analysis divided the samples into three distinct groups (GI, GII and GIII) that were confirmed by principal-coordinate analysis. The genetic distances (GD) were correlated with important agronomic traits for single-cross hybrids and heterosis. No correlation was found when group division was not considered, but significant correlations were detected between GI×GII and GI×GIII GDs with their respective single-cross hybrid grain-yield values. Three groups were identified; that is, the BR-106 population was divided in two different groups and the BR-105 population remained mostly as one group. The results indicated that RAPD can be used as a tool for determining the extent of genetic diversity among tropical maize inbred lines, for allocating genotypes into different groups, and also to aid in the choice of the superior crosses to be made among maize inbred lines, so reducing the number of crosses required under field evaluation.

Parallel simulated annealing applied to long term transmission network expansion planning

Abstract: The simulated annealing optimization technique has been successfully applied to a number of electrical engineering problems, including transmission system expansion planning. The method is general in the sense that it does not assume any particular property of the problem being solved, such as linearity or convexity. Moreover, it has the ability to provide solutions arbitrarily close to an optimum (i.e. it is asymptotically convergent) as the cooling process slows down. The drawback of the approach is the computational burden: finding optimal solutions may be extremely expensive in some cases. This paper presents a parallel simulated annealing (PSA) algorithm for solving the long-term transmission network expansion planning problem. A strategy that does not affect the basic convergence properties of the sequential simulated annealing algorithm have been implemented and tested. The paper investigates the conditions under which the parallel algorithm is most efficient. The parallel implementations have been tested on three example networks: a small 6-bus network; and two complex real-life networks. Excellent results are reported in the test section of the paper: in addition to reductions in computing times, the PSA algorithm proposed in the paper has shown significant improvements in solution quality for the largest of the test networks.

Giant magnetoimpedance effect in soft magnetic wires for sensor applications

Abstract: The giant magneto-impedance effect (GMI) consists of the large relative change of the impedance (up to around 300%) observed in magnetically very soft ribbon and wire alloys under the application of dc magnetic fields (units of kA m 1 ). The phenomenology of the GMI effect is firstly described including a discussion about its origin which mainly lies in the classical skin-effect. An alternative approach to GMI phenomena considering equivalent circuits is also introduced. The main requirements to detect GMI is to count on a sample with very large circular susceptibility and reduced resistivity provided the frequency of the ac current flowing along the sample (necessary to evaluate the impedance) is high enough (roughly above 0.1 MHz for most samples here considered). The dependence on dc magnetic field, mechanical stresses and particularly on thermal treatments resulting in the induced magnetic anisotropies or in the devitrification of amorphous samples into a nanocrystalline structure are reviewed. First results on GMI in glass-coated amorphous microwires are also reported. The use of the GMI as a tool for studying the inner circular magnetization process or for evaluating the magnetostriction is introduced. Finally, a description on various aspects regarding the development of magnetic field, current, proximity and stress sensor applications is presented.

Modelos tecno-assistenciais em saúde: da pirâmide ao círculo, uma possibilidade a ser explorada

Abstract: The technical health care model that portrays the health system as a pyramid with ascending and descending flows of users obtaining access to differentiated levels of technological complexity within articulated reference and counter-reference processes has been conceived as a rationalizing perspective, the merit of which would be to provide greater efficiency in the use of resources, in addition to universal, equitable access. In practical terms, by assuming that facts occur differently than intended under a certain technocratic rationality, the author provides some explanations for this "distortion". He also defends the idea that the health system would be more adequately thought of as a circle, containing multiple "portals of entry" located at several points in the system rather than at a presupposed "base". The author also questions the sense of a "top level", a kind of expression related to a certain "technological hierarchy" with the hospital occupying the apex. At the same time he highlights the health system as an entity to be organized focusing on what is most relevant to each user, offering the most adequate technology in the right place and at the most appropriate time.

Influence of the distribution of magnetic moments on the magnetization and magnetoresistance in granular alloys

Abstract: In granular solids, the magnetoresistance is directly related to the macroscopic magnetization, but this relationship is extremelly complex due to the distribution of grain sizes and the intergranular magnetic interactions The dependence of the magnetoresistance on the magnetization is here investigated by means of a theoretical model that is developed taking explicitly into account the magnetic moment distribution and the spin-dependent electron-impurity scattering within magnetic grains and at the interface between the grains and the metallic matrix Using this model, one can explain large experimental deviations from the parabolic behavior of the magnetoresistance vs magnetization curves that are typically expected for equal noninteracting superparamagnetic grains The expressions for the magnetization and magnetoresistance, obtained for general distribution funtions, are tested considering a log-normal-type distribution function by fitting on data obtained from melt-spun Cu${}_{90}$Co${}_{10}$ ribbons after annealing by dc Joule heating The experimental data are well traced using just three parameters that determine the particle size distribution, the particle density, and the ratio of the scattering cross section at the boundaries of the grains to the scattering cross section within the grains

On the numerical simulation of waterflooding of heterogeneous petroleum reservoirs

Abstract: We present a new, naturally parallelizable, accurate numerical method for the solution of transport-dominated diffusion processes in heterogeneous porous media For the discretization in time of one of the governing partial differential equations, we introduce a new characteristics-based procedure which is mass conservative, the modified method of characteristics with adjusted advection (MMOCAA) Hybridized mixed finite elements are used for the spatial discretization of the equations and a new strip-based domain decomposition procedure is applied towards the solution of the resulting algebraic problems We consider as a model problem the two-phase immiscible displacement in petroleum reservoirs A very detailed description of the numerical method is presented Following that, numerical experiments are presented illustrating the important features of the new method and comparing computed results with ones derived from previous, related techniques

Sugarcane Yellow Leaf Disease in Brazil: Evidence of Association with a Luteovirus

Abstract: Evidence of the viral etiology of sugarcane yellow leaf disease (SCYLD), occurring in southeast Brazil, was obtained by light and electron microscopy combined with serology. Light microscopy using epifluorescence illumination showed an abnormal yellow-green fluorescing material in the phloem of SCYLD-affected plants that was rarely observed in control plants. Immunolocalization in tissue-printed (or -blotted) nitrocellulose membranes, using barley yellow dwarf virus (BYDV) serotype PAV antiserum, showed a weak but clearly positive reaction in the phloem. Isometric viruslike particles of 24 to 26 nm in diameter were found by electron microscopy both in situ and in partially purified preparations. Examination of thin sections showed that phloem companion cells contained viruslike particles and presented cytological changes apparently related to the development of virus infection. Partially purified preparations produced UV absorption spectra typical of a nucleoprotein, with high absorbance at 260 nm, as expected for isometric virus particles. Virus particles were observed in extracts and partially purified preparations using immunosorbent electron microscopy with BYDV-PAV antiserum. Plate-trapped antigen enzyme-linked immunosorbent assays with the same antiserum indicate a weak serological relationship between BYDV-PAV and SCYLD-associated virus.

Comparative studies on nonconvex optimization methods for transmission network expansion planning

Abstract: We have investigated and extensively tested three families of nonconvex optimization approaches for solving the transmission network expansion planning problem: simulated annealing (SA), genetic algorithms (GA), and tabu search algorithms (TS). The paper compares the main features of the three approaches and presents an integrated view of these methodologies. A hybrid approach is then proposed which presents performances which are far better than the ones obtained with any of these approaches individually. Results obtained in tests performed with large scale real-life networks are summarized.

Seed dispersal and predation in two populations of Cabralea canjerana (Meliaceae) in the Atlantic Forest of southeastern Brazil

Abstract: The seed dispersal system of a neotropical tree, Cabralea canjerana (Meliaceae), was studied in two forested areas in southeastern Brazil. The first study site, Parque Estadual Intervales (PEI), is a 49,000-ha reserve composed mostly of old-growth Atlantic rain forest. The second site, Mata de Santa Genebra (MSG), is a 250-ha fragment of old-secondary semideciduous forest whose present bird fauna differs markedly from the original, in part as a consequence of forest fragmentation. At PEI 35 bird species ate the diaspores of C. canjerana. Black-tailed tityra (Tityra cayana, Tyrannidae) was the main seed disperser, but several other species were also important seed dispersers. In contrast, at MSG C. canjerana diaspores were eaten by 14 bird species. At this area, the red-eyed vireo (Vireo olivaceus, Vireonidae) was the most important seed disperser, but it was also a ‘waster’ which dropped seeds beneath parent plants, or carried them to sites unsuitable for germination. At PEI, exposed seeds on the forest floor were heavily preyed upon by rodents and insects. Insects destroyed mainly seeds deposited near to parent plants. Insect predation was less intense at MSG than at PEI. The rodent density at MSG was unusually small, and part of the post-dispersal seed predation may be done by terrestrial birds, such as doves and tinamous, which are especially common at MSG. Some of the differences recorded between the seed dispersal systems of C. canjerana at PEI and MSG may have been the result of the fragmentation and isolation of the latter area.

HPLC and Mass Spectrometric Analysis of Carotenoids from Mango

Abstract: β-Carotene (all-trans), β-cryptoxanthin (all-trans and cis), zeaxanthin (all-trans), luteoxanthin isomers, violaxanthin (all-trans and cis), and neoxanthin (all-trans and cis) were identified in mango cultivar Keitt by means of HPLC data (retention time, co-injection, and chemical reactions). Mass spectrometry (molecular ion, fragmentation pattern, m/z relative intensity) confirmed the identity of these carotenoids (not the geometric form); additionally, lutein and mutatochrome were detected when a large amount of sample was utilized. The quantitative composition was determined by HPLC, Sudan I being used as internal standard. all-trans-Violaxanthin (21.1 ± 2.9 μg/g), all-trans-β-carotene (15.1 ± 1.5 μg/g), and a cis-violaxanthin (10.1 ± 0.2 μg/g), tentatively identified as 9-cis, were the principal carotenoids. Keywords: Mango carotenoids; HPLC; MS