Antimicrobial Bacterial Cellulose-Silver Nanoparticles Composite Membranes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeito do tratamento de sementes com fungicidas e acibenzolar-S-methyl no controle da ferrugem asiática e crescimento de plântulas em cultivares de soja

A influência de acibenzolar-S-methyl (ASM), e fungicidas aplicados via tratamento de sementes sobre a ferrugem asiática bem como o crescimento de plântulas de soja foi avaliada em experimento conduzido em casa de vegetação em delineamento inteiramente casualizado com três repetições, utilizando as cultivares de soja 'Agiara', 'M-soy 8000' e 'M-soy 8080'. Os tratamentos foram três doses de ASM (0,05; 0,1 e 0,2 g de i.a. por kg de sementes), ASM (na dose de 0,1 g de i.a. por kg de sementes) combinado aos fungicidas flutriafol, pyraclostrobin e azoxystrobin, e a aplicação isolada destes, além de uma testemunha tratada com água. Os resultados mostraram redução da Área Abaixo da Curva de Progresso da Ferrugem (AACPF) com o aumento da dose de ASM nas três cultivares de soja. A utilização isolada do ASM em diferentes doses proporcionou uma redução da AACPF além de apresentar, na maioria dos casos, um efeito sinérgico com os fungicidas, aumentando a eficiência de controle quando comparada às aplicações isoladas. Com exceção do ASM na menor dosagem, todos os tratamentos apresentaram controle superior a 77 % comparados à testemunha. em geral, o tratamento de sementes com ASM e fungicidas resultou numa redução da massa seca (MS) em relação à testemunha. A utilização de ASM associado a fungicidas na tentativa de atrasar a infecção da ferrugem asiática da soja nos períodos iniciais da cultura constitui-se em uma alternativa viável para redução do inóculo inicial, entretanto possíveis efeitos fitotóxicos devem ser considerados.

Ação de acibenzolar-s-methyl (BTH) isolado e em combinação com fungicidas no controle do cancro da haste em melão rendilhado

Determinou-se as melhores épocas de aplicação e dosagens do BTH e seu efeito no controle do cancro da haste isoladamente ou em combinação com fungicidas. Foram testadas duas doses de BTH (2,5 e 5,0 g/100L) aplicadas aos 11; 18; 22 e 24 dias após transplantio das mudas. Utilizou-se o delineamento inteiramente casualizado, no esquema fatorial 2 x 4 (doses x épocas) com oito repetições. Posteriormente, utilizou-se a melhor época e dose de BTH associada aos fungicidas: difenoconazole (30 mL de p.c./100L), azoxystrobin (16 mL de p.c./100L) alternado com chlorothalonil (250 g de p.c./100L) e chlorothalonil (250 g de p.c./100L). Utilizou-se também BTH isoladamente e benomyl (70 g de p.c./100L) sem a adição de BTH. As aplicações foram realizadas em intervalos de sete dias até os 28 dias após o transplantio. Os seis tratamentos foram distribuídos inteiramente ao acaso em 15 repetições. Avaliou-se a severidade da doença por meio de escala de notas. Os resultados encontrados demonstraram que a associação de difenoconazole + BTH foi mais eficiente no controle do cancro da haste em melão rendilhado.

Experimental lamellar keratoplasty in rabbits using microfibrilar cellulose membrane: clinical, morphological and immunohistochemical findings

Avaliaram-se aspectos clínicos, histopatógicos e imunoistoquímicos da córnes de coelhos da raça Nova Zelândia adultos e machos em ceratoplastias lamelares com membrana de celulose microfibrilar. Trinta animais distribuídos em cinco grupos (n=6) foram estudados por até 60 dias de pós-operatório. A avaliação clínica revelou manifestações moderadas de edema, blefaroespasmo e fotofobia ao segundo dia, evoluindo para formas discretas ou ausentes a partir do sétimo dia, período em que se observou, clinicamente, reparo do defeito corneal. A histopatologia revelou uma fina camada de células escamosas, recobrindo a área lesada já aos sete dias, com discreto infiltrado de células polimorfonucleares. Observaram-se vasos no epitélio a partir do 15o dia, com regressão ao 48o dia. A marcação com o anticorpo Ki67 mostrou aumento de células em proliferação aos 15 dias no epitélio e aos 30 dias no estroma. Nesse período, ocorreram remodelamento e adesão epitealial. Considerando a boa integração do implante, admite-se a membrana de celulose como um bom material a ser utilizado em ceratoplastia lamellar.

Quercetagetin 7-methyl ether glycosides from Paepalanthus vellozioides and Paepalanthus latipes

Several new quercetagetin 7-methyl ether glycosides were characterized from the ethanolic extracts of scapes and leaves of Paepalanthus vellozioides and P. latipes. Their structures were determined mainly by 600 MHz NMR spectroscopy. (C) 1999 Elsevier B.V. Ltd. All rights reserved.

Xylanases from fungi: properties and industrial applications

Xylan is the principal type of hemicellulose. It is a linear polymer of beta-D-xylopyranosyl units linked by (1-4) glycosidic bonds. In nature, the polysaccharide backbone may be added to 4-O-methyl-alpha-D-glucuronopyranosyl units, acetyl groups, alpha-L-arabinofuranosyl, etc., in variable proportions. An enzymatic complex is responsible for the hydrolysis of xylan, but the main enzymes involved are endo-1,4-beta-xylanase and beta-xylosidase. These enzymes are produced by fungi, bacteria, yeast, marine algae, protozoans, snails, crustaceans, insect, seeds, etc., but the principal commercial source is filamentous fungi. Recently, there has been much industrial interest in xylan and its hydrolytic enzymatic complex, as a supplement in animal feed, for the manufacture of bread, food and drinks, textiles, bleaching of cellulose pulp, ethanol and xylitol production. This review describes some properties of xylan and its metabolism, as well as the biochemical properties of xylanases and their commercial applications.

Characterization and catalytic activity of iron(III) mono(4-N-methyl pyridyl)-tris(halophenyl) porphyrins in homogeneous and heterogeneous systems

The synthesis, characterization and catalytic activity of the cationic iron porphyrins Fe[M(4-N-MePy)TDCPP]Cl-2 and Fe[M(4-N-MePy)TFPP]Cl-2 in the epoxidation of (Z)-cyclooctene by PhIO in homogeneous solution and supported on silica gel (SG), imidazole propyl gel (IPG) or SG modified with 2-(4-sulfonatophenyl)ethyl groups (SiSO3) have been accomplished. When supported on IPG, both cationic FeP bind to the support via Fe-imidazole coordination. Fe[M(4-N-MePy)TDCPP]IPG contains a mixture of low-spin bis-coordinated (FeP)-P-III and high-spin mono-coordinated (FeP)-P-III species, whereas Fe[M(4-N-MePy)TFPP]IPG only contains high-spin mono-coordinated (FeP)-P-III. These FePIPG catalysts also contain (FeP)-P-II species, whose presence was confirmed by EPR spectroscopy using NO as a paramagnetic probe. Both cationic FePs coordinate to SG through Fe-O ligation and they are present as high-spin (FeP)-P-III species. The cationic FePs supported on SiSO3- are also high-spin (FeP)-P-III species and they bind to the support via electrostatic interaction between the 4-N-methylpyridyl groups and the SO3- groups present on the matrix. In homogeneous solution, both Fe[M(4-N-MePy)TDCPP]Cl-2 and Fe[M(4-N-MePy)TFPP]Cl-2 have similar catalytic activity to Fe(TDCPP)Cl and Fe(TFPP)Cl, leading to cis-epoxycyclooctane yields of 92%. When supported on inorganic matrices,both FePs lead to epoxide yields comparable to their homogeneous analogues and their anchoring enables catalyst recovery and re-use. Recycling of Fe[M(4-N-MePy)TDCPP]SiSO3- shows that this FeP maintains its activity in a second reaction. (C) 1999 Elsevier B.V. B.V. All rights reserved.

Characterization of methylcellulose produced from sugar cane bagasse cellulose: Crystallinity and thermal properties

In the present work, methylcellulose produced from sugar cane bagasse was characterized by FTIR, WAXD, DTA and TGA techniques. Two samples were synthesized: methylcellulose A and rnethylcellulose B. The only difference in the process was the addition of fresh reactants during the preparation of methylcellulose B. The ratio between the absorption intensities of the C-H stretching band at around 2900 cm(-1) and C-H stretching at around 3400 cm(-1) for methylcellulose B is higher than for methylcellulose A, indicating that methylcellulose B showed an increase in the degree of substitution (DS). Methylcellulose A presents a more heterogeneous structure, which is similar to the original cellulose as seen through FTIR and DTA. Methylcellulose B showed thermal properties similar to commercial methylcellulose. The modification of rnethylcellulose preparation method allows the production of a material with higher DS, crystallinity and thermal stability in relation to the original cellulose and to methylcellulose A. (c) 2006 Elsevier Ltd. All rights reserved.

Fluorescence study of the interaction between metal ions and methyl methacrylate methacrylic acid copolymers in aqueous solutions: thallium(I), calcium(II), and terbium(III)

The binding of the cations thallium(I), calcium(II) and terbium(III) to methyl methacrylate-methacrylic acid copolymers with different fractions of acid groups (x) has been studied in aqueous solution at, various pH values using the fluorescence of covalently bonded 9-vinyl anthracene as a probe. In all cases, the extent of binding increases as a function of the charge of the polymer with either increasing fraction of carboxylic acids or of pH. However, differences are observed in the behavior of the three cations, With Tl(I), quenching of the anthracene group fluorescence is observed. indicating that the thallium(I) approaches the probe and suggesting that the alkylanthracene is probably in a relatively polar region. Binding constants have been determined from anthracene quenching data and from studies with the fluorescent-probe sodium pyrenetetrasulfonate, Good agreement is obtained between the two methods, and values for the binding constants increase from 250 to 950 M-1 as x increases from 0.39 to 1. It is suggested that the cation is held in the polyelectrolyte domain, partly by Debye-Huckel effects and partly by more specific interactions. Stronger binding is found with calcium(II) and terbium(III), and in this case increases in fluorescence intensity are observed on complexation due to the anthracene group being in a more hydrophobic region, probably as a result of conformational changes in the polymer chain. In the former case the stoichiometry of the interaction was determined from the fluorescence data to involve two carboxylate groups bound per calcium. Association constants were found using murexide as an indicator of free calcium to vary from 8400 to 37 000 M-1 as x increases from 0.39 to 1. It is suggested that in this case specific calcium(II)-carboxylate interactions contribute to the binding. With terbium(III), a greater increase in the probe fluorescence intensity was observed than with calcium, and it is suggested that the interaction with the polymer is even stronger, leading to a more pronounced conformational change in the polymer. It is proposed that the terbium(III) interacts with sis carboxylic groups on the polymer chain, with three being coordinated and three attracted by electrostatic interactions.

Identification of polycyclic aromatic hydrocarbons and methoxylated phenols in wood smoke emitted during production of charcoal

More than 130 organic substances in dichloromethane-methanol (4: 1) extracts of particulate matter and the gaseous phase from wood burning for the production of charcoal have been identified by capillary gas chromatography coupled with low-resolution mass spectrometry (GC-MS), use of GC retention indices, and comparison with authentic standards. Many of the substances identified are methoxyphenols (derivatives of syringol and guaiacol), polycyclic aromatic hydrocarbons (PAH), oxidized PAH (oxy-PAH), and levoglucosan, the last being a monosoccharide derivative from the thermal breakdown of cellulose. The amount of unsubstituted PAH was greater than that of methyl- and dimethyl-substituted homologs.

Crystal structure of potassium trifluoro(2-methyl-1,3-dithiano)borate, K(C5H9BF3S2)

C5H9BF3KS2, triclinic, P (1) over bar (no. 2), a = 11.9238(5) angstrom, b = 13.6060(5) angstrom, c = 14.0280(3) angstrom, alpha = 114.995(2)degrees, beta = 92.035(2)degrees, gamma = 92.390(2)degrees, V = 2057.4 angstrom(3), Z = 8, R-gt(F) = 0.049, wR(ref)(F-2) = 0.117, T = 296 K.

Evidence of room temperature charge-density wave behavior and glass-like states in pressed pellets of lightly doped poly (3-methyl thiophene)

We show room temperature charge-density wave (CDW) characteristics in d.c. and a.c. electric data in pressed pellets of lightly doped poly(3-methylthiophene). The possibility of a Peierls glass is discussed and metastables states are observed. D.C. and A.C. data also show a state with negative differencial resistance.