Use of sugarcane bagasse as biomaterial for cell immobilization for xylitol production

This study provides a preliminary contribution to the development of a bioprocess for the contintious production of xylitol from hemicellulosic hydrolyzate utilizing Candida guilliermondii cells immobilized onto natural sugarcane bagasse fibers. To this purpose, cells of this yeast were submitted to batch tests of ""in situ"" adsorption onto crushed and powdered sugarcane bagasse after treatment with 0.5 M NaOH. The results obtained on a xylose-based semi-synthetic medium were evaluated in terms of immobilization efficiency, cell retention and specific growth rates of suspended, immobilized and total cells. The first two parameters were shown to increase along the immobilization process, reached maximum values of 50.5% and 0.31 g immobilized cells/g bagasse after 21 h and then sharply decreased. The specific growth rate of suspended cells continuously increased during the immobilization tests, while that of the immobilized ones, after an initial growth, exhibited decreasing values. Under the conditions selected for cell immobilization, fermentation also took place with promising results. The yields of xylitol and biomass on consumed xylose were 0.65 and 0.18 g/g, respectively, xylitol and biomass productivities 0.66 and 0.13 g L-1 h(-1), and the efficiency of xylose-to-xylitol bioconversion was 70.8%. (C) 2007 Elsevier Ltd. All rights reserved.

Manufacture and characterization of ultra and microfiltration ceramic membranes by isostatic pressing

This paper describes the manufacture of tubular UF and MF porous and supported ceramic membranes to oil/water emulsions demulsification. For such a purpose, a rigorous control was realized over the distribution and size of pores. Suspensions at 30 vol.% of solids (zirconia or alumina powder and sucrose) and 70 vol.% of liquids (isopropyl alcohol and PVB) were prepared in a jar mill varying the milling time of the sucrose particles, according to the pores size expected. The membranes were prepared by isostatic pressing method and structurally characterized by SEM, porosimetry by mercury intrusion and measurements of weight by immersion. The morphological characterization of the membranes identified the formation of porous zirconia and alumina membranes and supported membranes. The results of porosimetry analysis by mercury intrusion presented an average pore size of 1.8 mu m for the microfiltration porous membranes and for the ultrafiltration supported membranes, pores with average size of 0.01-0.03 mu m in the top-layer and 1.8 mu m in the support. By means of the manufacture method applied, it was possible to produce ultra and microfiltration membranes with high potential to be applied to the separation of oil/water emulsions. (C) 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Cement stabilization of runoff residuals: A study of stabilization/solidification of urban rainfall-runoff residuals in type 1 Portland cement by XRD and Si-29 NMR analysis

Urban rainfall-runoff residuals contain metals such as Cr, Zn, Cu, As, Pb and Cd and are thus reasonable candidates for treatment using Portland cement-based solidification-stabilization (S/S). This research is a study of S/S of urban storm water runoff solid residuals in Portland cement with quicklime and sodium bentonite additives. The solidified residuals were analyzed after 28 days of hydration time using X-ray powder diffraction (XRD) and solid-state Si-29 nuclear magnetic resonance (NMR) spectroscopy. X-ray diffraction (XRD) results indicate that the main cement hydration products are ettringite, calcium hydroxide and hydrated calcium silicates. Zinc hydroxide and lead and zinc silicates are also present due to the reactions of the waste compounds with the cement and its hydration products. Si-29 NMR analysis shows that the coarse fraction of the waste apparently does not interfere with cement hydration, but the fine fraction retards silica polymerization.

Montmorillonite as a component of polysulfone nanocomposite membranes

Nanocomposite membranes containing polysulfone (PSI) and sodium montmorillonite from Wyoming (MMT) were prepared by a combination of solution dispersion and the immersion step of the wet-phase inversion method. The purpose was to study the MMT addition with contents of 0.5 and 3.0 mass% MMT in the preparation of nanocomposite membranes by means of morphology, thermal, mechanical and hydrophilic properties of nanocomposite membranes and to compare these properties to the pure PSf membrane ones. Small-angle X-ray diffraction patterns revealed the formation of intercalated clay mineral layers in the PSf matrix and TEM images also presented an exfoliated structure. A good dispersion of the clay mineral particles was detected by SEM images. Tensile tests showed that both elongation at break and tensile strength of the nanocomposites were improved in comparison to the pristine PSf. The thermal stability of the nanocomposite membranes, evaluated by onset and final temperatures of degradation, was also enhanced. The hydrophilicity of the nanocomposite membranes, determined by water contact angle measurements, was higher; therefore, the MMT addition was useful to produce more hydrophilic membranes. (C) 2009 Elsevier B.V. All rights reserved.

Direct drinking water treatment by spiral-wound ultrafiltration membranes

This paper presents the results of a research on direct drinking water treatment through an ultrafiltration pilot plant unit using spiral-wound membranes (3500 MWCO). The source of water is the Guarapiranga Reservoir, an eutrophicated water body located in the metropolitan region of Sao Paulo, Brazil. The data were collected during a period of almost 3400 h, from August 2005 to January 2006. The main objective of the study was to evaluate the membrane production capacity and contaminant removal efficiency. It was verified that the system was able to produce a high quality permeate with a flow close to the specified by the membrane manufacturer. The average permeate flow was 19.7 L.h(-1).m(-2), at 467 kPa and 25 degrees C, with a global water recovery of almost 85%. The removal efficiencies for TOC, UV light absorption, and turbidity were 85%, 56%, and 95%, respectively. The results provide substantial evidence of the technical feasibility of spiral-wound UF membranes for direct drinking water treatment from euthrophicated sources, as an alternative for conventional drinking water treatment systems.

Differential ultrastructural changes in tomato hormonal mutants exposed to cadmium

Cadmium (Cd) is a toxic heavy metal, which can cause severe damage to plant development. The aim of this work was to characterize ultrastructural changes induced by Cd in miniature tomato cultivar Micro-Tom (MT) mutants and their wild-type counterpart. Leaves of diageotropica (dgt) and Never ripe (Nr) tomato hormonal mutants and wild-type MT were analysed by light, scanning and transmission electron microscopy in order to characterize the structural changes caused by the exposure to 1 mM CdCl(2). The effect of Cd on leaf ultrastructure was observed most noticeably in the chloroplasts, which exhibited changes in organelle shape and internal organization, of the thylakoid membranes and stroma. Cd caused an increase in the intercellular spaces in Nr leaves, but a decrease in the intercellular spaces in dgt leaves, as well as a decrease in the size of mesophyll cells in the mutants. Roots of the tomato hormonal mutants, when analysed by light microscopy, exhibited alterations in root diameter and disintegration of the epidermis and the external layers of the cortex. A comparative analysis has allowed the identification of specific Cd-induced ultrastructural changes in wild-type tomato, the pattern of which was not always exhibited by the mutants. (C) 2009 Elsevier B.V. All rights reserved.

Influence of Urea, Isopropanol, and Propylene Glycol on Rutin In Vitro Release from Cosmetic Semisolid Systems Estimated by Factorial Design

Rutin, one of the major flavonoids found in an assortment of plants, was reported to act as a sun protection factor booster with high anti-UVA defense, antioxidant, antiaging, and anticellulite, by improvement of the cutaneous microcirculation. This research work aimed at evaluating the rutin in vitro release from semisolid systems, in vertical diffusion cells, containing urea, isopropanol and propylene glycol, associated or not, according to the factorial design with two levels with center point. Urea (alone and in association with isopropanol and propylene glycol) and isopropanol (alone and in association with propylene glycol) influenced significant and negatively rutin liberation in diverse parameters: flux (g/cm2.h); apparent permeability coefficient (cm/h); rutin amount released (g/cm2); and liberation enhancement factor. In accordance with the results, the presence of propylene glycol 5.0% (wt/wt) presented statistically favorable to promote rutin release from this semisolid system with flux = 105.12 8.59 g/cm2.h; apparent permeability coefficient = 7.01 0.572 cm/h; rutin amount released = 648.80 53.01 g/cm2; and liberation enhancement factor = 1.21 0.07.

Preparation and characterization of ethanol-treated silk fibroin dense membranes for biomaterials application using waste silk fibers as raw material

The possibility of producing valued devices from low cost natural resources is a subject of broad interest. The present study explores the preparation and characterization of silk fibroin dense membranes using waste silk fibers from textile processing. Morphology, crystallinity, thermal resistance and cytotoxicity of membranes as well as the changes on the secondary structure of silk fibroin were analyzed after undergoing treatment with ethanol. Membranes presented amorphous patterns as determined via X-ray diffraction. The secondary structure of silk fibroin on dense membranes was either random coil (silk I) or p-sheet (silk II), before and after ethanol treatment, respectively. The sterilized membranes presented no cytotoxicity to endothelial cells during in vitro assays. This fact stresses the material potential to be used in the fabrication of biomaterials, as coatings of cardiovascular devices and as membranes for wound dressing or drug delivery systems. (C) 2010 Elsevier Ltd. All rights reserved.

A New Method to Prepare Porous Silk Fibroin Membranes Suitable for Tissue Scaffolding Applications

A new method to prepare porous silk fibroin (SF) membranes without dialysis proposed. Silk fibers were degummed to remove sericin and the resultant fibroin was dissolved in a CaCl(2)-CH(3)CH(2)OH-H(2)O ternary solvent. Rather than undergoing dialysis, a fibroin salty solution was diluted in water and then submitted to a mechanical agitation that led to a phase separation through foam formation on the solution surface. This foam was continually collected and then compacted between plates to remove the excess of water. The membranes presented large pores with diameters of greater than 100 pm (as shown by scanning electron microscopy - SEM), porosity of 68% and water content of 91% w/w. X-ray diffraction (XRD) and infrared spectroscopy (FTIR-ATR) indicated that the membranes present SF in a beta-sheet structure even before the ethanol treatment. A typical elastic deformation profile and degradation under temperature were observed using calorimetric analysis (DSC), thermal gravimetric analysis (TGA) and mechanical tests. As indicated by the in vitro cytotoxicity tests, these membranes present potential for use as scaffolds. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 617-623, 2009

Heterologous expression of an Aspergillus niveus xylanase GH11 in Aspergillus nidulans and its characterization and application

A xylanase was cloned from Aspergillus niveus and successfully expressed in Aspergillus nidulans (XAN). The full-length gene consisted of 890 bp and encoded 275 mature amino acids with a calculated mass of 31.3 kDa. The deduced amino acid sequence was highly homologous with the xylanase belonging to family 11 of the glycoside hydrolases. The recombinant protein was purified to electrophoretic homogeneity by anion-exchange chromatography and gel filtration. The optima of pH and temperature for the recombinant enzyme were 5.0 and 65 degrees C, respectively. The thermal stability of the recombinant xylanase was extremely improved by covalent immobilization on glyoxyl agarose with 91.4% of residual activity after 180 min at 60 degrees C, on the other hand, the free xylanase showed a half-life of 9.9 min at the same temperature. Affinity chromatography on Concanavalin A- and Jacalin-agarose columns followed by SDS-PAGE analyses showed that the XAN has O- and N-glycans. XAN promotes hydrolysis of xylan resulting in xylobiose, xylotriose and xylotetraose. Intermediate degradation of xylan resulting in xylo-oligomers is appealing for functional foods as the beneficial effect of oligosaccharides on gastrointestinal micro flora includes preventing proliferation of pathogenic intestinal bacteria and facilitates digestion and absorption of nutrients. (C) 2011 Elsevier Ltd. All rights reserved.

Calcium Carbonate Particle Growth Depending on Coupling among Adjacent Layers in Hybrid LB/LbL Films

There are practical and academic situations that justify the study of calcium carbonate crystallization and especially of systems that are associated with organic matrices and a confined medium. Despite the fact that many different matrices have been studied, the use of well-behaved, thin organic films may provide new knowledge about this system. In this work, we have studied the growth of calcium carbonate particles on well-defined organic matrices that were formed by layer-by-layer (LbL) polyelectrolyte films deposited on phospholipid Langmuir-Blodgett films (LB). We were able to change the surface electrical charge density of the LB films by changing the proportions of a negatively charged lipid, the sodium salt of dimyristoyl-sn-glycero-phosphatidyl acid (DMPA), and a zwitterionic lipid. dimyristoyl-sn-glycero-phosphatidylethanolamine (DMPE). This affects the subsequent polyelectrolyte LbL film deposition, which also changes the the nature of the bonding (electrostatic interaction or hydrogen bonding). This approach allowed for the formation of calcium carbonate particles of different final shapes, roughnesses, and sizes. The masses of deposited lipids, polyelectrolytes, and calcium cabonate were quantified by the quartz crystal microbalance technique. The structures of obtained particles were analyzed by scanning electron microscopy.

Mitochondria, endoplasmic reticulum and actin filament behavior after PDT with chloroaluminum phthalocyanine liposomal in HeLa cells

Photodynamic therapy (PDT) for cancer is a therapeutic modality in the treatment of tumors in which visible light is used to activate a photosensitizer. Cell membranes have been identified as an important intracellular target for singlet oxygen produced during the photochemical pathway. This study analyzed the cytotoxicity in specific cellular targets of a photosensitizer used in PDT in vitro. The photosensitizing effects of chloroaluminum phthalocyanine liposomal were studied on the mitochondria, cytoskeleton and endoplasmic reticulum of HeLa cells. Cells were irradiated with a diode laser working at 670 nm, energy density of 4.5 J/cm(2) and power density of 45 mW/cm(2). Fluorescence microscopic analysis of the mitochondria showed changes in membrane potential. After PDT treatment, the cytoskeleton and endoplasmic reticulum presented basic alterations in distribution. The combined effect of AlPHCl liposomal and red light in the HeLa cell line induced photodamage to the mitochondria, endoplasmic reticulum and actin filaments in the cytoskeleton. (c) 2008 International Federation for Cell Biology. Published by Elsevier Ltd. All rights reserved.

Surface miscibility of EPC/DOTAP/DOPE in binary and ternary mixed monolayers

Surface pressure (pi)-molecular area (A) curves were used to characterize the packing of pseudo-ternary mixed Langmuir monolayers of egg phosphatidylcholine (EPC), 1,2-dioleoyl-3-trimethylammonium propane (DOTAP) and L-alpha-dioleoyl phosphatidylethanolamine (DOPE). This pseudo-ternary mixture EPC/DOPE/DOTAP has been successfully employed in liposome formulations designed for DNA non-viral vectors. Pseudo-binary mixtures were also studied as a control. Miscibility behavior was inferred from pi-A curves applying the additivity rule by calculating the excess free energy of mixture (Delta G(Exc)). The interaction between the lipids was also deduced from the surface compressional modulus (C(s)(-1)). The deviation from ideality shows dependence on the lipid polar head type and monolayer composition. For lower DOPE concentrations, the forces are predominantly attractive. However, if the monolayer is DOPE rich, the DOTAP presence disturbs the PE-PE intermolecular interaction and the net interaction is then repulsive. The ternary monolayer EPC/DOPE/DOTAP presented itself in two configurations, modulated by the DOPE content, in a similar behavior to the DOPE/DOTAP monolayers. These results contribute to the understanding of the lipid interactions and packing in self-assembled systems associated with the in vitro and in vivo stability of liposomes. (C) 2010 Elsevier B.V. All rights reserved.

Permeabilization of E-coli K12 inner and outer membranes by bothropstoxin-I, A LYS49 phospholipase A2 from Bothrops jararacussu

Although lacking catalytic activity, the Lys49-PLA(2)s damage artificial membranes by a Ca2+-independent mechanism, and demonstrate a potent bactericidal effect. The relationship between the membrane-damaging activity and bactericidal effect of bothropstoxin-I (BthTx-1), a Lys49-PLA(2) from the venom of Bothrops jararacussu, was evaluated for the wildtype protein and a series of site-directed mutants in the active site and C-terminal regions of the protein. The membrane permeabilization effect against the inner and outer membranes of Escherichia coli K12 was evaluated by fluorescence changes of Sytox Green and N-phenyl-N-naphthylamine, respectively. With the exception of H48Q, all mutants reduced the bactericidal activity, which correlated with a reduction of the permeabilization effect both against the inner bacterial membrane. No significant differences in the permeabilization of the bacterial outer membrane were observed between the native, wild-type recombinant and mutant proteins. These results suggest different permeabilization mechanisms against the inner and outer bacterial membranes. Furthermore, the structural determinants of bacterial inner membrane damage identified in this study correlate with those previously observed for artificial membrane permeabilization, suggesting that a common mechanism of membrane damage underlies the two effects. (C) 2007 Elsevier Ltd. All rights reserved.

Rare Earth Doped SnO(2) Nanoscaled Powders and Coatings: Enhanced Photoluminescence in Water and Waveguiding Properties

Luminescent Eu(3+) and Er(3+) doped SnO(2) powders have been prepared by Sn(4+) hydrolysis followed by a controlled growth reaction using a particle`s surface modifier in order to avoid particles aggregation. The powders so obtained doped with up to 2 mol% rare earth ions are fully redispersable in water at pH > 8 and present the cassiterite structure. Particles size range from 3 to 10 nm as determined by Photon Correlation Spectroscopy. Rare earth ions were found to be essentially incorporated into the cassiterite structure, substituting for Sn(4+), for doping concentration smaller than 0.05 mol%. For higher concentration they are also located at the particles surface. The presence of Eu(3+) ions at the surface of the particles hinder their growth and has therefore allowed the preparation of new materials consisting of water redispersable powders coated with Eu(3+)-beta dike-tonate complexes. Enhanced UV excited photoluminescence was observed in water. SnO(2) single layers with thickness up to 200 nm and multilayer coatings were spin coated on borosilicate glass substrates from the colloidal suspensions. Waveguiding properties were evaluated by the prism coupling technique. For a 0.3 mu m planar waveguide single propagating mode was observed with attenuation coefficient of 3.5 dB/cm at 632.8 nm.