Alvaro Luiz Mathias

Fractionation of Eucalyptus grandis chips by dilute acid-catalysed steam explosion

Steam explosion of Eucalyptus grandis has been carried out under various pretreatment conditions (200-210 degrees C, 2-5 min) after impregnation of the wood chips with 0.087 and 0.175% (w/w) H2SO4. This study, arranged as a 2(3) factorial design, indicated that pretreatment temperature is the most critical variable affecting the yield of steam-treated fractions. Pretreatment of 0.175% (w/w) H2SO4-impregnated chips at 210 degrees C for 2 min was the best condition for hemicellulose recovery (mostly as xylose) in the water soluble fraction, reaching almost 70% of the corresponding xylose theoretical yield. By contrast, lower pretreatment temperatures of 200 degrees C were enough to yield steam-treated substrates from which a 90% cellulose conversion was obtained in 48 h, using low enzyme loadings of a Celluclast 1.5 1 plus Novozym 188 mixture (Novo Nordisk). Release of water-soluble chromophores was monitored by UV spectroscopy and their concentration increased with pretreatment severity. The yield of alkali-soluble lignin increased at higher levels of acid impregnation and pretreatment temperatures. Thermoanalysis of these lignin fractions indicated a pattern of lignin fragmentation towards greater pretreatment severities but lignin condensation prevailed at the most drastic pretreatment conditions.

Polyaniline/lignin blends: FTIR, MEV and electrochemical characterization

Abstract Blends of polyaniline (emeraldine base) and Eucalyptus grandis kraft lignin were prepared by casting method. The maximum amount of lignin that could be used for blending was 36% (w/w); beyond that, fractile films were produced. The IR spectra of the blends indicated that interactions occurred between polyaniline and lignin. Cyclic voltammetry measurements showed peaks that were readily attributed to the oxidation/reduction of polyaniline and a new oxi-reduction peak due to oxidation/reduction of sites created during interaction of two polymers. Scanning electronic microscopy showed that all blends were homogeneous.

Chemical composition of Ulvaria oxysperma (Kützing) bliding, Ulva lactuca (Linnaeus) and Ulva fascita (Delile)

A composicao quimica de tres especies de Chlorophyta foi determinada. Ulva lactuca se desenvolve em Guaraquecaba e Ulva fasciata na Ilha do Mel, enquanto que Ulvaria oxysperma se desenvolve nos dois ecossistemas. Umidade (16-20%), cinzas (17-31%, base seca), proteinas (6-10%bs), lipideos (0,5-3.2%bs), fibras (3-12%bs) e carboidratos (46-72%bs) para U.oxysperma correspondeu a 192-270 kcal.100g-1 (base umida). U.lactuca (15-18%bs) e U.fasciata (13-16%bs) mostraram teores levemente maiores para a proteina, mas com conteudos energeticos similares (250-272 e 225-239 kcal.100g-1), respectivamente. As folhas in natura de U.lactuca e de U.fasciata eram mais rigidas do que as de U.oxysperma. Outras algas nativas apresentaram teores de proteinas maiores. Ulvaria sp pode ser cultivada sobre redes, sem apresentar competicao com outras algas ou acao significativa de predadores. Ulvaria sp cultivada apresentou composicao quimica similar ao da Ulvaria sp crescida sobre substratos naturais. E essencial escolher um local protegido da acao destrutiva da mare.

Pré-tratamentos na secagem e reidratação de champignon em fatias

The objective of this paper was assessments the effect of pre-treatment (pt) in osmo-convective dehydration: Chemical pretreatment at 20°C for 5min with 0.1% solution of citric acid, sodium bisulfite and calcium carbonate (pt-ABC) and bleaching at 80°C for 5min (pt-B), as well the combination pt-ABC followed by pt-B (sample:solution = 1:10 w/w). The pt-ABC provoked mass increase (13% on average), while pt-B caused loss (-34% on average). Osmotic dehydration at 20°C for 60 min with 10% NaCl reduced mass of slices not pretreated at 43%. This level of mass reduction was not achieved for the pt-ABC, but it was improved for 49% to slices subjected to pt-B. Pretreatments reduced drying time (70°C and air circulation 18m³ h-1) from 150min to 60min to achieve the desired aw. Water activity of dried product was equal to or less than the commercial product. Slices subjected to pt-ABC or from control group had good rehydration capacity. Slices subjected to combined pt and dried showed lighter color and were less wrinkled. pt-ABC allowed very similar results. The pt-ABC must be used to obtain slices of dry champignon with visual aspect and rehydration capacity suitable for the development of new products for direct consumption or require rehydration.

Effect of matrix composition, sphere size and hormone concentration on diffusion coefficient of insulin for controlled gastrointestinal delivery for diabetes treatment

Abstract Oral insulin administration is limited due to its degradation by proteases. The hormone was encapsulated in spheres made of either pure calcium alginate (ALG) or its association with whey protein isolate (WPI-ALG) in order to minimise loss in the stomach region while allowing liberation in the maximum absorption area, located in the intestine. Diffusion coefficients for both matrix compositions were determined in vitro for gastric pH (5.88 and 10.26 × 10−12 m2 s−1) and intestinal pH (21.11 and 79.29 × 10−12 m2 s−1). Higher initial insulin concentrations and lower diameters accelerated its release, confirming Fickian behaviour. The analytic model exhibited a good fit in most cases. Computer simulations revealed that ALG spheres are more convenient for oral administration because they release more insulin in the intestine than the WPI-ALG ones, thus supporting its therapeutic viability for the purpose of reducing stress in those who depend on insulin.

Fotodegradação heterogênea de efluente de polpa kraft branqueada com cloro

The wood cellulose pulp must be bleached to reach a high commercial value. Chlorine is very effective in bleaching for pulp obtained by chemical process, but it also produces highly polluting and toxic byproducts. Other bleaching chemicals have been proposed to reduce toxicity, but they are more expensive and less versatile. Catalytic photodegradation using ultraviolet radiation (UV) was performed to assess the potential for reducing the content of pollutants in an effluent from bleaching cellulose pulp by using chlorine. The Pinus taeda cellulose pulp was produced and bleached in laboratory. Three liters of effluent received 3g of titanium dioxide (TiO2) and were submitted to UV radiation. UV was produced with the use of a mercury- vapor bulb in high-pressure of 250 W (12,500 Lm) for 240 min. Photodegradation to 25 oC for 240 min with UV decreased about 43% of the color, 40% of the BOD5 (biochemical oxygen demand), 50% of the COD (chemical oxygen demand), 40% of calcinable material and 45% of TOC (total organic carbon), in addition to decreasing the toxicity LC50 (lethal concentration - 50%) for the treated effluent. The bioindicator Artemia salina showed the survival time greater than 1,000% for the treated effluent. The experimental points distribution from 0 to 240 min suggests that the photodegradation must be extended. Thus, the reduction of pollutants observed suggests that advanced oxidation process (AOP), using UV-TiO2 photocatalytic oxidation may be convenient to treat chlorinated bleaching effluents. This can enable the safe use of chlorine bleaching.

Oral tissue response to ovine grafting biomaterial: Morphological and morphometric study using scanning electron and light microscopy tissue response to ovine grafting biomaterial

OBJECTIVE: To evaluate the oral tissue response to an experimental particle ovine biomaterial by scanning electron microscopy (SEM) and light microscopy (LM). MATERIAL AND METHODS: Forty‐eight rats had surgical periodontal defects treated with either blood clotting (control), bovine biomaterial™ (B), or an experimental ovine biomaterial (O). Data from SEM analysis (defect exposure, root surface exposure, diameter of matrix fibers and bundles, and globuli areas; n = 5) were applied to Shapiro–Wilk, Kruskal–Wallis, and Dunns test, whereas LM analysis (tissue cicatrization characteristics and diameter defect; n = 3) had data applied to two‐way analysis of variance. Animals were monitored for 1 and 3 weeks. RESULTS: By SEM, the O samples showed significant differences from B and C in the area of defect exposure (H2,15 = 8.66; P < 0.05). In both periods, O and B samples showed similar results for matrix fiber diameters, differently than C samples (H2,15 = 14.0; P < 0.05). All other SEM variables were considered equivalent among the groups (P > 0.05). Under LM, an acute and chronic granulomatous inflammation was seen in the presence of both biomaterials (B and O, 1 week); both the control and the ovine grafting samples showed mature bone in the repair site (3 weeks); the defect diameter showed similar values among groups, at both monitoring periods (F2,12 = 1.0401; P > 0.05). CONCLUSION: The ovine particles of this study showed a favorable response to oral tissue repair, demonstrating to be a potential source for the development of bone grafting biomaterials. Microsc. Res. Tech. 2012.