Microwave treatment of human milk to prevent transmission of Chagas disease

It is recognized that breast feeding is an alternative means of transmission of Chagas disease. However, thermal treatment of milk can prevent this occurrence. As domestic microwave ovens are becoming commonplace, the efficacy of microwave thermal treatment in inactivating Trypanosoma cruzi trypomastigotes in human milk was tested. Human milk samples infected with T. cruzi trypomastigotes (Y strain) from laboratory-infected mice, were heated to 63 °C in a domestic microwave oven (2 450 MHz, 700 W). Microscopical and serological examinations demonstrated that none of the animals inoculated orally or intraperitoneally with infected milk which had been treated, got the infection, while those inoculated with untreated, infected milk, became infected. It was concluded that the simple treatment prescribed, which can easily be done at home, was effective in inactivating T. cruzi trypomastigotes contained in human milk.

The ceramic artifacts in archaeological black earth (terra preta) from lower Amazon region, Brazil: mineralogy

Several archaeological black earth (ABE) sites occur in the Amazon region. They contain fragments of ceramic artifacts, which are very important for the archaeological purpose. In order to improve the archaeological study in the region we carried out a detailed mineralogical and chemical study of the fragments of ceramic artifacts found in the two ABE sites of Cachoeira-Porteira, in the Lower Amazon Region. Their ceramics comprise the following tempers: cauixi, cariapé, sand, sand +feldspars, crushed ceramic and so on and are composed of quartz, clay equivalent material (mainly burned kaolinite), feldspars, hematite, goethite, maghemite, phosphates, anatase, and minerals of Mn and Ba. Cauixi and cariapé, siliceous organic compounds, were found too. The mineralogical composition and the morphology of their grains indicate a saprolite (clayey material rich on quartz) derived from fine-grained felsic igneous rocks or sedimentary rocks as source material for ceramic artifacts, where silica-rich components such cauixi, cariapé and/or sand (feldspar and rock fragments) were intentionally added to them. The high content of (Al,Fe)-phosphates, amorphous to low crystalline, must be product of the contact between the clayey matrix of pottery wall and the hot aqueous solution formed during the daily cooking of animal foods (main source of phosphor). The phosphate crystallization took place during the discharge of the potteries put together with waste of organic material from animal and vegetal origin, and leaving to the formation of the ABE-soil profile.

The ceramic artifacts in archaeological black earth (terra preta) from Lower Amazon Region, Brazil: chemistry and geochemical evolution

This paper carried out a chemical investigation of archaeological ceramic artifacts found in archaeological sites with Black Earth (ABE) in the Lower Amazon Region at Cachoeira-Porteira, State of Pará, Brazil. The ceramic artifacts, mostly of daily use, belong to Konduri culture (from 900 to 400 years BP). They are constituted of SiO2, Al2O3, Fe2O3, Na2O and P2O5; SiO2 and Al2O3 together add up to 80 % and indicate influence of acid rocks, transformed into clay minerals basically kaolinite. The relative high contents of P2O5 (2.37 % in average) come out as (Al,Fe)-phosphate, an uncommon fact in primitive red ceramics, but found in some roman and egyptian archaeological sites. The contents of the trace elements are similar or below the Earth's crust average. This chemical composition (except P2O5) detaches saprolite material derived acid igneous rocks or sedimentary ones as the main raw material of the ceramics. The contents of K, Na and Ca represent the feldspars and rock fragments possibly introduced into saprolitic groundmass, indicated by mineralogical studies. The presence of cauixi and cariapé as well as quartz sand was confirmed by optical microscope, SEM analyses and by the high silica contents of ceramic fragments. Phosphorus was possibly incorporated into groundmass during cooking of foods, and ABE soil profile formation developed on yellow Latosols. The raw materials and its tempers (cauixi, or cariapé, feldspar, crushed rocks, old ceramic artifacts and quartz fragments) are found close to the sites and therefore and certainly came from them.

Molecular and morphological characterization of hydrochar produced by microwave-assisted hydrothermal carbonization of cellulose

The objective of this work was to characterize the morphology and molecular composition of the hydrochar produced by microwave-assisted hydrothermal carbonization of cellulose. The produced hydrochar consists mainly of aggregate microspheres with about 2.0 µm in diameter, with aliphatic and aromatic structures and the presence of carbonyl functional groups. The aromatic groups are formed mainly by benzofuran-like structures, being chemically different from common cellulose char. Microwave-assisted hydrothermal carbonization yields a functionalized carbon-rich material similar to that produced by the conventional hydrothermal process.

Determination of nitrate in lettuce by ion chromatography after microwave water extraction

Lettuce is worldwide known as the most important vegetable. In this context, most farmers are searching new techniques for best quality products including hydropony. However, nitrate is of great concern, since it has a negative impact on human metabolism. The main objective of the present work was to evaluate the nitrate content of lettuce produced by conventional and hydroponic systems. The determination was conducted by ion chromatography and a new method of extraction was tested using microwave oven digestion. The results indicated that nitrate level produced in the conventional system was lower than in the hydroponic system.

Efficient synthesis of sulfonamide derivatives on solid supports catalyzed using solvent-free and microwave-assisted methods

In this work we report the synthesis of sulfonamide derivatives using a conventional procedure and with solid supports, such as silica gel, florisil, alumina, 4Å molecular sieves, montmorillonite KSF, and montmorillonite K10 using solvent-free and microwave-assisted methods. Our results show that solid supports have a catalytic activity in the formation of sulfonamide derivatives. We found that florisil, montmorillonite KSF, and K10 could be used as inexpensive alternative catalysts that are easily separated from the reaction media. Additionally, solvent-free and microwave-assisted methods were more efficient in reducing reaction time and in increasing yield.

Synthesis of quinoxaline 1,4-di-N-oxide derivatives on solid support using room temperature and microwave-assisted solvent-free procedures

We describe the synthesis of 12 new ethyl and methyl quinoxaline-7-carboxylate 1,4-di-N-oxide derivatives on solid supports with room temperature and microwave-assisted solvent-free procedures. Results show that solid supports have good catalytic activity in the formation of quinoxaline 1,4-di-N-oxide derivatives. We found that florisil and montmorillonite KSF and K10 could be used as new, easily available, inexpensive alternatives of catalysts. Additionally, room temperature and microwave-irradiation solvent-free synthesis was more efficient than a conventional procedure (Beirut reaction), reducing reaction time and increasing yield.

Use of heterogeneous catalysts in methylic biodiesel production induced by microwave irradiation

The effect of different heterogeneous catalysts on the microwave-assisted transesterification of sunflower oil for the production of methylic biodiesel in a monomode microwave reactor is described. The experiments were carried out at 70 ºC with a 16:1 methanolsunflower oil molar ratio and different heterogeneous basic and acidic catalysts. The results showed that the microwave-heated reactions occur up to four times faster than those carried out with conventional heating. The reactions were performed with 24 catalysts; pure calcium oxide (CaO) and potassium carbonate, either pure or supported by alumina (K2CO3/Al2O3), were the most efficient catalysts.

MICROWAVE ACTIVATION OF IMMOBILIZED LIPASE FOR TRANSESTERIFICATION OF VEGETABLE OILS

This work investigated the effect of microwave irradiation (MW) on the ethanolysis rate of soybean and sunflower oils catalyzed by supported Novozyme 435 (Candida antarctica). The effects of tert-butanol, water addition and oil:ethanol molar ratio on transesterification were evaluated under conventional heating (CH), and under optimum reaction conditions (with no added water in the system, 10% tert-butanol and 3:1 ethanol-to-oil molar ratio). The reactions were monitored up to 24 h to determine the conditions of initial reaction velocity. The investigated variables under MW (50 W) were: reaction time (5.0-180 min) and mode of reactor operation (fixed power, dynamic and cycles) in the absence and presence of tert-butanol (10% (w/w). The measured response was the reaction conversion in ethyl esters, which was linked to the enzyme catalytic activity. The results indicated that the use of microwave improved the activity at fixed power mode. A positive effect of the association of tert-butanol and MW irradiation on the catalytic activity was observed. The reaction rate improved in the order of approximately 1.5 fold compared to that under CH with soybean oil. Using soybean oil, the enzymatic transesterification under MW for conversion to FAEE (fatty acid ethyl esters) reached >99% in 3h, while with the use of CH the conversions were about 57% under similar conditions.

Spectrophotometric determination of diclofenac in pharmaceutical preparations assisted by microwave oven

In this work, an effective and low-cost method for the determination of sodium or potassium diclofenac is proposed in its pure form and in their pharmaceutical preparations. The method is based on the reaction between diclofenac and tetrachloro-p-benzoquinone (p-chloranil), in methanol medium. This reaction was accelerated by irradiating of reactional mixture with microwave energy (1100 W) during 27 seconds, producing a charge transfer complex with a maximum absorption at 535 nm. The optimal reaction conditions values such as reagent concentration, heating time and stability of the reaction product were determined. Beer's law is obeyed in a concentration range from of 1.25x10-4 to 2.00x10-3 mol l-1 with a correlation coefficient of 0.9993 and molar absorptivity of 0.49 x10³ l mol-1 cm-1. The limit of detection (LOD) was 1.35x10-5 mol l-1 and the limit of quantification (LOQ) was 4.49x10-5 mol l-1. In the presence of the common excipients, such as glucose, lactose, talc, starch, magnesium stearate, sodium sulphite, titanium dioxide, polyethyleneglycol, polyvinylpirrolidone, mannitol and benzilic alcohol no interferences were observed. The analytical results obtained by applying the proposed method compare very favorably with those given by the United States Pharmacopeia standard procedure. Recoveries of diclofenac from various pharmaceutical preparations were within 95.9% to 103.3%, with standard deviations ranging from 0.2% to 1.8%.

Synthesis and characterization of Fe(III)-doped ceramic membranes of titanium dioxide and its application in photoelectrocatalysis of a textile dye

Pure and Fe(III)-doped TiO2 suspensions were prepared by the sol gel method with the use of titanium isopropoxide (Ti(OPri)4) as precursor material. The properties of doped materials were compared to TiO2 properties based on the characterization by thermal analysis (TG-DTA and DSC), X-ray powder diffractometry and spectroscopy measurements (FTIR). Both undoped and doped TiO2 suspensions were used to coat metallic substrate as a mean to make thin-film electrodes. Thermal treatment of the precursors at 400ºC for 2 h in air resulted in the formation of nanocrystalline anatase TiO2. The thin-film electrodes were tested with respect to their photocatalytic performance for degradation of a textile dye in aqueous solution. The plain TiO2 remains as the best catalyst at the conditions used in this report.

Microwave-assisted solvent extraction and analysis of shikimic acid from plant tissues

A better method for determination of shikimate in plant tissues is needed to monitor exposure of plants to the herbicide glyphosate [N-(phosphonomethyl)glycine] and to screen the plant kingdom for high levels of this valuable phytochemical precursor to the pharmaceutical oseltamivir. A simple, rapid, and efficient method using microwave-assisted extraction (MWAE) with water as the extraction solvent was developed for the determination of shikimic acid in plant tissues. High performance liquid chromatography was used for the separation of shikimic acid, and chromatographic data were acquired using photodiode array detection. This MWAE technique was successful in recovering shikimic acid from a series of fortified plant tissues at more than 90% efficiency with an interference-free chromatogram. This allowed the use of lower amounts of reagents and organic solvents, reducing the use of toxic and/or hazardous chemicals, as compared to currently used methodologies. The method was used to determine the level of endogenous shikimic acid in several species of Brachiaria and sugarcane (Saccharum officinarum) and on B. decumbens and soybean (Glycine max) after treatment with glyphosate. The method was sensitive, rapid and reliable in all cases.

Optimized Fast-FISH with a-satellite probes: acceleration by microwave activation

It has been shown for several DNA probes that the recently introduced Fast-FISH (fluorescence in situ hybridization) technique is well suited for quantitative microscopy. For highly repetitive DNA probes the hybridization (renaturation) time and the number of subsequent washing steps were reduced considerably by omitting denaturing chemical agents (e.g., formamide). The appropriate hybridization temperature and time allow a clear discrimination between major and minor binding sites by quantitative fluorescence microscopy. The well-defined physical conditions for hybridization permit automatization of the procedure, e.g., by a programmable thermal cycler. Here, we present optimized conditions for a commercially available X-specific a-satellite probe. Highly fluorescent major binding sites were obtained for 74oC hybridization temperature and 60 min hybridization time. They were clearly discriminated from some low fluorescent minor binding sites on metaphase chromosomes as well as in interphase cell nuclei. On average, a total of 3.43 ± 1.59 binding sites were measured in metaphase spreads, and 2.69 ± 1.00 in interphase nuclei. Microwave activation for denaturation and hybridization was tested to accelerate the procedure. The slides with the target material and the hybridization buffer were placed in a standard microwave oven. After denaturation for 20 s at 900 W, hybridization was performed for 4 min at 90 W. The suitability of a microwave oven for Fast-FISH was confirmed by the application to a chromosome 1-specific a-satellite probe. In this case, denaturation was performed at 630 W for 60 s and hybridization at 90 W for 5 min. In all cases, the results were analyzed quantitatively and compared to the results obtained by Fast-FISH. The major binding sites were clearly discriminated by their brightness

STABILITY OF OILS HEATED BY MICROWAVE: UV - SPECTROPHOTOMETRIC EVALUATION

The effects of microwave heating on the oxidative stability of refined canola, corn and soybean oils were determined by absorptivity in the UV spectrum and by chemical analysis (peroxide and acid values). Samples were heated in a microwave oven (800 W, 2,450 MHz) for 0 to 36 min. Microwave heating produced oxidative degradation in the three oils. Absorptivity at 232 and 270 nm increased gradually with an increase in microwave exposure time (0-36 min) for canola, corn and soybean oils. Values of absorptivity at 232 nm increased from 4.812, 3.568 and 4.183 to 10.579, 12.874 and 15.950 after 36 min of heating canola, corn and soybean oil, respectively. The absorptivity at 232nm, due to the formation of conjugated dienes, was a good index for measuring the degradation of microwaved samples. UV scanning (220 - 320 nm) detected alterations in the spectrum of microwaved samples. Acid value also increased within 36 min of heating for all oils. Peroxide value showed a significant difference (P<0.05) in the initial stage of heating (0-6 min) for all oils. After this period it could not be correlated with absorptivity at 232 nm, due to the instability of hydroperoxides at high temperatures.

Physicochemical and sensory profile of rice bran roasted in microwave

The purpose of this study was to evaluate the physical, chemical, and sensory changes in bran from three rice cultivars according to microwave roasting time. This study analyzed three rice cultivars, BRS Sertaneja (S), BRS Primavera (P), and IRGA 417 (I) determining the color parameters (L*, a*, and b *) at 6, 9, 12, 15, and 18 minutes of roasting time. After applying the difference from control test, the rice brans with different characteristics aroma and flavor were selected: S and P roasted for 9 and 15 minutes and IRGA 417 roasted for 9, 12, and 15 minutes. These samples were characterized by Free-Choice Profile descriptive sensory analysis, and their chemical composition was also determined. The longer the roasting process, the higher the roasted flavor intensity and aroma. The IRG 417 cultivar roasted for 12 minutes showed a sweeter flavor and aroma. After roasting, the brans remained rich in protein and lipid and presented higher fiber content and lower reducing sugar and phytic acid content. Microwave roasting for 12 minutes can be a viable option for improving the sensory functional and nutritional characteristics of the rice bran considering its use in food products.