Showing papers by "Universidade Federal de Santa Catarina published in 2002"

Kinetics of photocatalytic degradation of reactive dyes in a TiO2 slurry reactor

Abstract: The textile industry consumes considerable amounts of water during the dyeing and finishing operations. Dyes are extensively used and hence wastewaters discharged in rivers or public sewage treatment plants are highly contaminated. In this work, a detailed investigation of the adsorption and photocatalytic degradation of the safira HEXL dye, an anionic azo dye of reactive class, is presented. H 2 O 2 and UV light have a negligible effect when they are used on their own. The adsorption of dye on the semiconductor shows a strong dependence on the pH and follows a Langmuir adsorption model. The photodegradation kinetics is discussed in terms of the Langmuir–Hinshelwood model. The effect of pH, amount of photocatalyst, UV light intensity and hydrogen peroxide concentration is discussed. The relative photonic efficiency of the system is reported using phenol as a standard organic compound.

Simultaneous photocatalytic Cr(VI) reduction and dye oxidation in a TiO2 slurry reactor

Abstract: The semiconductor photocatalytic reduction is a relatively new technique for the removal of dissolved metal ions, such as Cr(VI) and organic compounds in wastewater. Many studies concern only the catalytic activity of TiO 2 with single substrates. However, for practical applications it is necessary to evaluate the photocatalytic simultaneous reduction and oxidation reactions. In this paper, we report the results of a study on the simultaneous Cr(VI) reduction and the Luranzol S Kong dye (from the tannery industry) oxidation by photocatalysis. The experiments were performed in a UV reactor system with a lamp of 150 W, using TiO 2 as a catalyst. We evaluated the effect of pH and concentration of pollutants on the kinetics of the reactions. Isolated tests showed that both Cr(VI) and Luranzol S Kong are degraded in acidic pH, according to the Langmuir–Hinshelwood kinetic model. In neutral pH, the Cr(VI) is not reduced, but this might be explained by the fact that Cr(VI) is not adsorbed on TiO 2 surface. The dye is almost completely degraded by both acidic and neutral pH. Under UV irradiation, photo-induced Cr(VI) reduction is observed in both Cr(VI)–TiO 2 and dye–Cr(VI)–TiO 2 , and dye oxidation is observed in both dye–TiO 2 and dye–Cr(VI)–TiO 2 . The concentration of Cr(VI) and dye, and the pH are the main parameters influencing both reactions. In the simultaneous reduction–oxidation process, the reduction of Cr(VI) proceeds quicker than it does in the single process, showing synergism between the oxidation and reduction reactions.

Traumatized primary teeth in children assisted at the Federal University of Santa Catarina, Brazil.

Abstract: The goal of this study was to determine factors related to the occurrence of dental trauma in permanent teeth of children assisted at the Pediatric Dentistry Clinic of the Federal University of Santa Catarina (UFSC) Florianopolis, Brazil. During a period of 18 months, 36 children between 7 and 12 years of age had 72 traumatized teeth treated. The children were all assisted by one professional, a dentist working as a trainee of the Pediatric Dentistry Clinic. The occurrence of trauma was higher in male patients (61.3%) and in children between 8 and 9 years old with an average age of mean=9.4 years. In the group assisted, 63.9% of the children had more than one traumatized tooth and trauma reoccurred 19.4% of the time. The maxillary anterior teeth represented 96.1% of the cases and the central incisor teeth were the most affected. Both sides of the mouth had approximately the same number of traumas. Fractures were more frequent (51.4%) than luxations (48.6%). Enamel/dentin crown fractures represented 51.4% of the total traumatized teeth. Falls were the main cause of trauma (83.3%). A dental professional assisted 36.1% of the children in some way during the first 24 h after the incident. The study concluded that the permanent dentition is mostly affected by crown fractures that occur especially on maxillary central incisor teeth in patients between 8 and 9 years of age. The major etiological factor is falls that affected more than one tooth. Re-occurrence of trauma is fairly common.

Associativity of crossed products by partial actions, enveloping actions and partial representations

Abstract: Given a partial action \alpha of a group G on an associative algebra A we consider the crossed product A x_\alpha G. Using the algebras of multipliers of ideals of A we prove that A x_\alpha G is associative, provided that all ideals of A are idempotent. This generalizes a previous result on the associativity of A x_\alpha G in the context of C*-algebras. We also give a criteria for the existence of a global extension of a given partial action on an algebra and use crossed products to study relations between partial actions of groups on algebras and partial representations. As an application we endow partial group algebras with crossed product structure.

Agmatine produces antidepressant-like effects in two models of depression in mice.

Abstract: Agmatine produces an antidepressant-like effect when assessed in the forced swimming test (FST) and in the tail suspension test (TST) in mice (dose range 0.01-50 mg/kg, i.p.), without accompanying changes in ambulation in an open-field. I.c.v. injection of agmatine (1-100 nmol/site) also reduced the immobility time in the FST. Agmatine significantly enhanced the anti-immobility effect of imipramine, but did not affect that of MK-801. The anti-immobility effect of agmatine assessed in the FST was not affected by pre-treatment with prazosin. In contrast, agmatine's antidepressant-like effect was completely prevented by pre-treatment of animals with yohimbine, GMP or L-arginine. Taken together these data demonstrate that agmatine elicited a significant antidepressant-like effect through a mechanism that seems to involve an interaction with NMDA receptors, the L-arginine-nitric oxide pathway and alpha2-adrenoceptors.

Ecological-friendly pigments from fungi.

Abstract: The dyestuff industry is suffering from the increases in costs of feedstock and energy for dye synthesis, and they are under increasing pressure to minimize the damage to the environment. The industries are continuously looking for cheaper, more environmentally friendly routes to existing dyes. The aim of this minireview is to discuss the most important advances in the fungal pigment area and its interest in biotechnological applications. Characteristic pigments are produced by a wide variety of fungi and the chemical composition of natural dyes are described. These pigments exhibit several biological activities besides cytotoxicity. The synthetic pigments authorized by the EC and in USA and the natural pigments available in the world market are discussed. The obstacle to the exploitation of new natural pigments sources is the food legislation, requesting costly toxicological research, manufacturing costs, and acceptance by consumers. The dislike for novel ingredients is likely to be the biggest impediment for expansion of the pigment list in the near future. If the necessary toxicological testing and the comparison with accepted pigments are made, the fungal pigments, could be acceptable by the current consumer. The potentiality of pigment production in Brazil is possible due to tremendous Amazonian region biodiversity.

Effect of bleaching agents on the hardness and morphology of enamel.

Abstract: Purpose: The goal of the present laboratory study was to analyze the effect of two home bleaching agents (Opalescence 10%, Ultradent, and Hi-Lite II, Shofu) as well as the separate solutions of 10% carbamide peroxide primary components (3% hydrogen peroxide and 7% urea) on enamel microhardness and surface morphology. Materials and Methods: Thirty human molars stored in water for no longer than 3 months were selected. Their facial and lingual surfaces were embedded in acrylic resin, and the specimens were polished with up to 600-grit sandpaper. The 30 molar sections were divided into five groups as per treatment modality (n = 6); group 1, 10% carbamide peroxide bleach with carbopol (Opalescence, Ultradent); group 2, oxygen-free gel bleach (Hydroxylite, Hi-Lite II, Shofu); group 3, 3% hydrogen peroxide with carbopol (Dermus Pharmacy, Florianopolis, SC, Brazil); group 4, 7% urea treatment (Dermus Pharmacy); and control, group 5, artificial saliva (Dermus Pharmacy). Prior to treatment, six indentations (Vickers) were made on each of the six surfaces in each group under a load of 100 g for 30 seconds. Bleaching procedure was conducted for 3 hours per day for 2 weeks, the control group excepted. Following each bleaching session, the specimens were washed with deionized water and kept in artificial saliva at 37°C, this solution being changed daily. Pre- and post-treatment microhardness data were analyzed using a two-way analysis of variance. In a similar way, 30 other specimens underwent the same procedures. After the bleaching period, the samples were observed under the scanning electron microscope. Results: Specimens submitted to bleaching treatment with 3% hydrogen peroxide gel as described in this study showed a significant reduction of surface microhardness (p < .0001). The other treatment modalities had no effect on surface microhardness. No morphologic alterations were observed on enamel submitted to bleaching gel of 10% carbamide peroxide (Opalescence), oxygen-free gel (Hi-Lite II, Shofu), or 7% urea solution compared with the control (artificial saliva). However, the specimens bleached for 3 hours per day for 2 weeks with 3% hydrogen peroxide gel presented areas of mild erosion. The effect, nevertheless, was not uniform, occurring with varying intensity on all samples of enamel bleached with 3% hydrogen peroxide. CLINICAL SIGNIFICANCE Bleaching treatment conducted with two home bleaching agents (Opalescence 10%, Ultradent, and Hi-Lite 11, Shofu) had no adverse effects on enamel microhardness or on surface morphology. Bleaching with 3% hydrogen peroxide can have a negative effect on enamel hardness and surface morphology when performed as described in this study

Partial dynamical systems and c -algebras generated by partial isometries

Abstract: A collection of partial isometries whose range and initial pro- jections satisfy a specified set of conditions often gives rise to a partial rep- resentation of a group. The corresponding C -algebra is thus a quotient of the universal C -algebra for partial representations of the group, from which it inherits a crossed product structure, of an abelian C -algebra by a partial action of the group. This allows us to characterize faithful representations and simplicity, and to study the ideal structure of these C -algebras in terms of amenability and topological freeness of the associated partial action. We also consider three specific applications: to partial representations of groups, to Toeplitz algebras of quasi-lattice ordered groups, and to Cuntz-Krieger algebras.

Epidemiological aspects of oral health among the elderly in Brazil

Abstract: All indexed articles in BBO, LILACS, and MEDLINE databases from January 1998 to July 2001 were searched to analyze information on oral health among the elderly in Brazil. The year 1998 was used as a starting point, since this was the year the National Epidemiological Survey was published. Twenty-nine articles were found, of which 7 were analyzed in detail regarding key methodological aspects (age, sampling, data presentation) and the results were presented (DMFT index, proportion of missing teeth, edentulousness rate, and use and need of dental prostheses). DMFT ranged from 26.8 to 31.0, with approximately 84% of teeth missing. Prevalence of edentulousness was 68%. Few elderly did not need or use any kind of prosthesis. Denture use was more frequent in the upper than in the lower jaw. Lack of standardized data hampered an understanding of some key aspects of data analysis. Both data presentation and methodology must be improved in future research in this area. Despite all these caveats, the literature review confirmed the poor oral health of the Brazilian elderly population.

Safety of sputum induction

Abstract: One of the most important recent advances in the investigation of airway inflammation has been the introduction of sputum induction by inhalation of an aerosol of hypertonic saline, by Pin et al. 1 in 1992, to directly obtain airway secretions in asthma. This method has a number of advantages over invasive methods. Safety and practicality are the most obvious. The method of obtaining induced sputum is relatively noninvasive and can be carried out at random 2 and repeatedly in subjects with varying disease severity 3–13. Therefore, it is not surprising that the examination of induced sputum has become the most clinically applicable method for the assessment of airway inflammation. The induction procedure is simple and safe. The risks in patients with stable asthma or chronic obstructive pulmonary disease (COPD) with mild­to­moderate airflow limitation are acceptable 1, 3–5, 8, 12–14. It can also be safe in patients with more severe airflow limitation 6, 10, 11 provided that the induction is performed with caution using a modified procedure 6. The safety of sputum induction has been specifically addressed in several recent publications 3–5, 12, 14. To date, there have been no reports of death or need for hospital admission in patients undergoing sputum induction for the assessment of airway inflammation; the airway constriction caused by sputum induction with hypertonic saline is quickly reversed by treatment with an inhaled short­acting β2‐agonist. It is well known, however, that inhalation of hypertonic or even isotonic saline can cause airway constriction in asthmatic subjects and in COPD, particularly in those with associated airway hyperresponsiveness (AHR). In 1958, Bickerman et al. 15, using aerosols of saline generated by jet nebuliser with concentrations ranging 3.0–15%, observed …

An inverse Jiles-Atherton model to take into account hysteresis in time-stepping finite-element calculations

Abstract: A modified Jiles-Atherton model presenting the magnetic induction as an independent variable is proposed in order to be directly used in time-stepping finite-element calculations applied to the magnetic vector potential formulation. This model is implemented in the field calculation procedure by introducing a differential reluctivity. The calculated results are validated by experiences performed in an Epstein's frame.

Mutational spectrum of the CHAC gene in patients with chorea-acanthocytosis.

Abstract: Chorea-acanthocytosis (ChAc) is an autosomal recessive neurological disorder whose characteristic features include hyperkinetic movements and abnormal red blood cell morphology. Mutations in the CHAC gene on 9q21 were recently found to cause chorea-acanthocytosis. CHAC encodes a large, novel protein with a yeast homologue implicated in protein sorting. In this study, all 73 exons plus flanking intronic sequence in CHAC were screened for mutations by denaturing high-performance liquid chromatography in 43 probands with ChAc. We identified 57 different mutations, 54 of which have not previously been reported, in 39 probands. The novel mutations comprise 15 nonsense, 22 insertion/deletion, 15 splice-site and two missense mutations and are distributed throughout the CHAC gene. Three mutations were found in multiple families within this or our previous study. The preponderance of mutations that are predicted to cause absence of gene product is consistent with the recessive inheritance of this disease. The high proportion of splice-site mutations found is probably a reflection of the large number of exons that comprise the CHAC gene. The CHAC protein product, chorein, appears to have a certain tolerance to amino-acid substitutions since only two out of nine substitutions described here appear to be pathogenic.

[Prevalence and risk factors associated with drug use among school students, Brazil].

Abstract: OBJETIVO: Analisar a prevalencia e os fatores de risco relacionados ao uso indevido de drogas entre estudantes de uma escola publica de primeiro e segundo graus. METODOS: Foi realizado estudo descritivo transversal, utilizando, como instrumento de pesquisa, um questionario anonimo, padronizado e amplamente testado no Brasil para levantamento do uso de drogas. A populacao estudada foi constituida de 478 estudantes de escola publica de primeiro e segundo graus, de Florianopolis, SC. Os questionarios foram aplicados por estudantes universitarios devidamente treinados. Entre os estudantes pesquisados, 43% e 32% foram de faixa etaria de 13 a 15 anos e de 16 a 18 anos, respectivamente, com predominio de classes socioeconomicas mais altas. RESULTADOS: A prevalencia de uso de maconha na vida (19,9%), solventes (18,2%), anfetaminicos (8,4%) e alcool (86,8%) foi elevada em Florianopolis, comparada a outras capitais da regiao Sul e a media brasileira. Notou-se elevado e frequente uso (seis ou mais vezes por mes) de alcool (24,2%), maconha (4,9%), solventes (2,5%) e anfetaminicos (2,3%). Os fatores demograficos relacionados ao uso de drogas na vida foram idade, sexo, classe socioeconomica e vida junto aos pais. A chance de garotas usarem remedios para emagrecer ou ficarem acordadas foi o dobro da chance de garotos e, quanto ao uso de tranquilizantes, quase o triplo. Os garotos tinham um risco quase duas vezes maior de uso de solvente do que as garotas. A classe socioeconomica alta foi associada a um risco duas vezes maior do uso de alcool do que a classe baixa. O risco de uso de cigarro e maconha na vida foi 84% e 67% maior, respectivamente, para alunos cujos pais estavam separados. CONCLUSAO: Constatou-se alta prevalencia de uso de varias drogas entre os alunos de primeiro e segundo graus.

Dental adhesion: present state of the art and future perspectives.

Abstract: Enamel adhesion by means of acid etching has become an accepted technique in restorative dentistry. Adhesion to dentin, however, is still under investigation. At this time, two distinct adhesive techniques are prominent in the attempt to establish a strong bond to dentin: total-etch and self-etching primers. Total-etch bonding systems have been shown to be effective both in vitro and in clinical evaluations. The new total-etch one-bottle bonding systems, although exhibiting the same success on laboratory tests, still have to prove their clinical effectiveness. Self-etching primer systems are undergoing rapid evolution; their results are not yet sufficiently predictable overall, but some systems have achieved positive results in both enamel and dentin bonding. Further studies are necessary to confirm the long-term efficiency of these self-etching primers.

Plantas usadas como medicinais no município de Ipê, RS, Brasil

Abstract: Foi realizado um levantamento das plantas medicinais utilizadas pela populacao do municipio de Ipe, RS, Brasil, visando uma investigacao da medicina tradicional, melhoramento e racionalizacao das praticas medicinais populares, em um projeto envolvendo voluntarios da comunidade. Foram entrevistadas 114 pessoas, que mencionaram 252 plantas, das quais foram identificadas 105 especies, agrupadas em 48 familias. As plantas coletadas e identificadas foram analisadas, de acordo com dados quimicos, farmacologicos e/ou toxicologicos encontrados na literatura cientifica. Os resultados obtidos mostram que a populacao deste municipio faz uso de plantas que, ainda, nao foram alvo de pesquisa quimica, farmacologica e/ou toxicologica e, tambem, que a mesma faz uso de onze especies, que sao reconhecidamente, responsaveis por efeitos colaterais indesejados, ou ainda, que sao toxicas.

Trapping Triatominae in silvatic habitats

Abstract: Large-scale trials of a trapping system designed to collect silvatic Triatominae are reported. Live-baited adhesive traps were tested in various ecosystems and different triatomine habitats (arboreal and terrestrial). The trials were always successful, with a rate of positive habitats generally over 20% and reaching 48.4% for palm trees of the Amazon basin. Eleven species of Triatominae belonging to the three genera of public health importance (Triatoma, Rhodnius and Panstrongylus) were captured. This trapping system provides an effective way to detect the presence of triatomines in terrestrial and arboreal silvatic habitats and represents a promising tool for ecological studies. Various lines of research are contemplated to improve the performance of this trapping system.