Utilização do resíduo líquido de indústria de processamento de suco de laranja como meio de cultura de Penicillium citrinum: depuração biológica do resíduo e produção de enzima

Penicillium citrinum grown in orange juice processing wastes medium under continuous agitation was studied in order to establish optimal conditions (incubation period, incubation temperature, initial pH and nitrogen addition) for biomass and ribonuclease production, as well as, biological depuration of the wastes. Nitrogen addition to wastes medium increased the biomass and ribonuclease production and provides COD reduction. The soy meal shows to be the best nitrogen source. The conditions for a more favorable enzyme and biomass production and COD reduction were initial pH 6.0 and temperature of 27°C. The maximum value obtained for these parameters on optimal conditions of cultivation was 11 U/mL of enzyme, 4 mg/mL of biomass (dry matter) and 55% of COD reduction, in 96 hours of incubation.

Oxidações eletrocatalíticas de álcoois e dióis em meio bifásico utilizando metanossulfonato de CeIV como mediador

Some alcohols and diols were oxidized electrocatalytically in a biphasic system using ceriumIV methanesulphonate as mediator. A mixture of methanesulphonic acid solution and benzene was used and aldehydes, ketones and diacids were some of the principal products obtained with yield varying from 27 to 98%. In several cases selectivity was obtained.

Estudo ab-initio da a-alanina em meio aquoso

Ab initio Hartree-Fock (HF), Density Functional (B3LYP) and electron correlation (MP2) methods have been used to caracterize the aqueous medium intramolecular hydrogen bond in a-alanine. The 6-31G* and 6-31++G** were taken from Gaussian94 library. We were concerned on the structure of three conformers of a-alanine, in their neutral form plus on the structure of the zwitterionic form (Z). The Z structure is a stationary point at the HF/6-31G* level but it is not when diffuse functions and electron correlation are included. This results shows that the Z form does not exist in the gas phase. The inclusion of solvent effects changed significantly the results obtained in gas phase, therefore this inclusion make the Z form a stationary point within all level of theory, and the relative energy depends dramatically on the level of calculation.

Caracterização de polimorfismo em fármacos por ressonância magnética nuclear no estado sólido

This review aims to present some features about solid state NMR and its application in the field of pharmaceutical chemistry, for the characterization of polymorphism of pharmaceutical molecules.

Influência da acidez do meio sobre a síntese e o comportamento redox do polipirrol

The influence of acidity on the synthesis and redox behavior of polypyrrole films was studied using galvanostatic and potentiodynamic techniques employing aqueous solutions formed by H2SO4/Na2SO4 , HCl/NaCl and HCl/CsCl. The chemical structure of the films were investigated using the FTIR technique. The polymer behavior as a function of the pH used in the cyclic voltammetric measurements is explained in terms of the mechanism responsible for the charge compensation formed during the polymer chain oxidation. From the FTIR measurements, it is seen that the water nucleophilic attack during the synthesis, does not occur under the experimental conditions employed in this work.

Reações orgânicas em meio aquoso

The use of water as solvent in organic reactions has been uncommon for several reasons, among them the low solubility of the reactants, the incompatibility of the intermediates with water, and the competition between the desired reaction and hydrolysis. Breslow in 1980, demonstrated that the hydrophobic effect accelerates Diels-Alder reactions and gives a high endo/exo selectivity. Since then, many other reactions were studied in this medium, and below we show the principal results. Besides the academic interest, human and economic aspects are included in this study. Water as a solvent minimizes environmental impact, costs and increases operational safety.

Influência do meio reacional no comportamento fotoquímico do inseticida paration etílico

The photodegradation of parathion in natural and dezionised waters was studied under irradiation at two different wavelengths: 280 nm and 313 nm. The influence of humic acids was evaluated. The results demonstrated that the degradation occurred only due to photochemical processes. The chemical hydrolysis and biological processes can be neglected in this case. The addition of humic acids did not increase the photodegradation rate in either water samples (natural or dezionised). In alkaline solutions the photodegradation rate was higher in dezionised water when compared to natural waters. The kinetic degradation in all experiments obeyed a first order reaction pattern.

Fotoquímica de chalconas fluoradas no estado sólido

Chalcone and its fluorinated derivatives were synthesized and photolyzed in the solid state. UV irradiation of chalcone and its monosubstituted fluorine derivatives (3- and 4-fluorchalcone) resulted in a mixture of anti-head-head (gamma-truxinic), sin-head-tail (alpha-truxilic) and anti-head-tail (epsilon-truxilic) dimers. On the other hand, upon irradiation of 3,4- and 3,5-difluorchalcone a stereoselective formation of the alpha-truxilic photodimer was observed, whereas for 2-substituted chalcones (2,3difluorchalcone, 2,5-difluorchalcone, 2,6-difluorchalcone and 2,3,4-trifluorchalcone) the beta-truxilic dimer was stereoselectively obtained. 2',3',4',5',6'-pentafluorchalcone was the less reactive of all chalcones studied and at least one of the possible photodimers, i.e the anti-head-head isomer, was identified. Irradiation of polyfluorinated chalcones such as 2,3,5,6-tetrafluor-, 2,3,4,5,6-pentafluor-, and 2,2',3,3',4,4',5,5',6,6'-decafluorchalcone led only to polymerization and/or decomposition products.

Propelente sólido compósito polibutadiênico: I- influência do agente de ligação

In the Brazilian Complete Spacial Mission, the research of Vehicle Satellite Launcher is important. The solid propellant composite used in this vehicle is made with ammonium perchlorate, aluminiun powder and hydroxy terminated polibutadiene resin. In the propellant the bonding agent has a function to promote the interaction between solids and polimeric matrix, improving mechanical properties as stress, strain, aging characteristics and moisture embrittlement. Due its importance in propellant, bonding agent is consider as industrial secret and the literature about it is generic, without greater informations.

Estudo da degradação do herbicida ácido 2,4- diclorofenoxiacético (2,4-D) por meio da radiação gama do cobalto-60 em solução aquosa contendo ácido húmico

The use of pesticides in agriculture presents some problems to ecosytems as a consequence of their remaining in the environment. Conventional methods for environmental decontamination sometimes just transfer these residues from one place to another. The use of gamma radiation from cobalt-60 to induce 2,4-D degradation in aqueous solution containing humic acid was studied. Results show that the herbicide is completely degraded after treatment with a 30 kGy dose. There were decreases in the degradation of the 2,4-D when humic acid was added at all doses. Some radiolytic products are proposed. The 2,4-D radiolytic yields (G) from 2,4-D were calculated.

Estudos de proteção da célula de saccharomyces cerevisiae para utilização em reações de redução em meio orgânico

New methodologies for protection of Saccharomyces cerevisiae (FP) cells when supported in montmorillonite K10 (K10), recovered or not with gelatin (G) and in the presence or absence of sucrose (S) are presented. These systems were used for the enantioselective reduction of ethyl acetoacetate and a-chloroacetophenone in hexane, under FP/K10/G/S and FP/S at 20ºC during 24 hours, affording S-(+)-ethyl-3-hydroxybutanoate in 100% conversion and 99% ee, and R-(-)-2-chloro-1-phenylethanol 79% and 78% ee at 20 and 30 ºC, respectivelly.

Caracterização e classificação do resíduo sólido "pó do balão", gerado na indústria siderúrgica não integrada a carvão vegetal: estudo de um caso na região de Sete Lagoas/MG

This research was developed by considering that the solid waste produced in the process of pig iron production represents the loss of raw materials and the increase in environmental problem. The charcoal based mini blast-furnace off gases dust named CHARCOK was collected from SIDERPA ¾ Siderúrgica Paulino Ltda, located in Sete Lagoas, Minas Gerais. The Charcok was characterized and classified according to ABNT (Associação Brasileira de Normas Técnicas) standard. The results showed that the Charcok should be classified as Class I Wastes ¾ "Hazard Wastes" because of its high concentration of phenols (54.5mg C6H5OH/kg). The Charcok had high concentration of iron and charcoal which can be used as energy source.

Fármacos no meio ambiente

Pharmaceutical drugs have been detected in sewage treatment plants, surface waters, underground waters and potable waters. Some investigations have been conducted in several countries such as Germany, Brazil, Canada, United States, The Netherlands, England and Italy. Patients and animals excrete part of pharmaceuticals used for human and veterinary medicine after administration in domestic sewage or on the soil. Drugs residues which have not been completely removed during passage through a sewage treatment plant (STP) enter the aquatic environment. The effects of such residual drugs in terrestrial and aquatic organisms are scarcely known.

Determinação da 2,5-hexanodiona em amostras de urina submetidas à hidrólise ácida: importância da coluna cromatográfica e do pH do meio

Acidic hydrolysis of samples is frequent in urinary 2,5-hexanodione determination. This hydrolysis should be performed under proper conditions, in order to avoid interference, such as the presence of 2,5-dimethylfurane and 2-acetylfurane. The results of the present work, as well as data from the literature, show that the use of non-polar or slightly polar chromatographic columns of 30 m length is an essential condition for 2,5-HD determination in an acid hydrolysed urine sample. In the same way the pH should be kept between 0.3 and 0.5. The mean concentrations of 2,5-HD in samples submitted to hydrolysis (0.50 ± 0.28 mg/g of creatinine) was about 3 times higher than those found in the samples without acid hydrolysis (0.19 ± 0.3 mg/g of creatinine).

Efeito do polietilenoglicol e da albumina na imobilização de lipase microbiana e na catálise em meio orgânico

Poly (ethylene) glycol (PEG) and bovine serum albumin (BSA), as additive agents, were used to enhance the activity of immobilized microbial lipase in organic solvent. Controlled pore silica (CPS) was selected as matrix and different immobilization procedures were evaluated: directly lipase binding on CPS and simultaneous addition of lipase and additive agent on the same support. The highest coupling yield (59.6%) was attained when the immobilization procedure was performed at lipase loading of 150 U/g support in the presence of PEG-1.500. This immobilized system was used in esterification reactions under repeated batch cycles and the biocatalyst half-life was found to increase 2.7 times when compared with the control.