Preparation and characterization of crosslinked resins containing ferrite particles

Micrometer-sized magnetic particles hosted on network material were successfully prepared by a simple chemical process (ion exchange followed by co-precipitation) from commercial styrene-divinylbenzene copolymers. Energy dispersive X-ray spectroscopy (EDS) coupled to scanning electron microscopy (SEM) allowed the observation of submicron particles. All the produced spherical beads have presented metallic particles (NiFe2O4, CuFe2O4, CoFe2O4, or MnFe2O4), either as isolated particles or agglomerates, located on their external and internal (within pores) The thermal stability of the composites, evaluated by thermogravimetric techniques, were found to be dependent on the amount of ferrite particles incorporated into them.

Prediction of Crude Oil Properties and Chemical Composition by Means of Steady-State and Time-Resolved Fluorescence

Steady-state and time-resolved fluorescence measurements are reported for several crude oils and their saturates, aromatics, resins, and asphaltenes (SARA) fractions (saturates, aromatics and resins), isolated from maltene after pentane precipitation of the asphaltenes. There is a clear relationship between the American Petroleum Institute (API) grade of the crude oils and their fluorescence emission intensity and maxima. Dilution of the crude oil samples with cyclohexane results in a significant increase of emission intensity and a blue shift, which is a clear indication of the presence of energy-transfer processes between the emissive chromophores present in the crude oil. Both the fluorescence spectra and the mean fluorescence lifetimes of the three SARA fractions and their mixtures indicate that the aromatics and resins are the major contributors to the emission of crude oils. Total synchronous fluorescence scan (TSFS) spectral maps are preferable to steady-state fluorescence spectra for discriminating between the fractions, making TSFS maps a particularly interesting choice for the development of fluorescence-based methods for the characterization and classification of crude oils. More detailed studies, using a much wider range of excitation and emission wavelengths, are necessary to determine the utility of time-resolved fluorescence (TRF) data for this purpose. Preliminary models constructed using TSFS spectra from 21 crude oil samples show a very good correlation (R(2) > 0.88) between the calculated and measured values of API and the SARA fraction concentrations. The use of models based on a fast fluorescence measurement may thus be an alternative to tedious and time-consuming chemical analysis in refineries.

Nanostructured diamond-like carbon films characterization

In this work, we have studied the influence of the substrate surface condition on the roughness and the structure of the nanostructured DLC films deposited by high-density plasma chemical vapor deposition Four methods were used to modify the silicon wafers surface before starting the deposition processes of the nanostructured DLC films. micro-diamond powder dispersion, micro-graphite powder dispersion, and roughness generation by wet chemical etching and roughness generation by plasma etching. The reference wafer was only submitted to a chemical cleaning. It was possible to see that the final roughness and the sp(3) hybridization degree (that is related with the structure and chemical composition) strongly depend on the substrate surface conditions The surface roughness was observed by AFM and SEM and the hybridization degree of the DLC films was analyzed by Raman Spectroscopy Thus, the effects of the substrate surface on the DLC film structure were confirmed. These phenomena can be explained by the fact that the locally higher surface energy and the sharp edges may induce local defects promoting the nanostructured characteristics in the DLC films. (C) 2009 Elsevier B.V. All rights reserved.

Carbide lime and industrial hydrated lime characterization

This paper focuses on the characterization of carbide lime (CL) - a by-product of acetylene production, composed mainly of calcium hydroxide with minor parts of carbonate - and compares its features to those of ""dry"" hydrated lime (HL) commonly used as a building material. Chemical, thermogravimetric and X-ray diffraction analyses indicated that the limes are similar in chemical and mineralogical compositions. except for the presence of carbon in the waste. Morphological and elemental chemical analyses by SEM and EDS revealed that CL particles differ from HL ones in their morphology and by the presence of carbon formations, Physical characterization included density and BET surface area of the materials. as well as, their particle size distributions in deionized water at diverse time periods. CL underwent agglomeration after approximately 60 min in water, whereas HL progressively became finer with time as determined by laser diffraction. In addition, water retention and squeeze flow tests were used to assess the pastes` fresh properties. (c) 2009 Elsevier B.V. All rights reserved.

Palynological and physicochemical characterization of Apis mellifera L. bee pollen in the Southern region of Brazil

Bee pollen has been used for many years in both traditional medicine and supplementary nutrition, as well as in alternative diets, mainly due to its nutritional properties and health benefits. Bee pollen production is a recent activity in Brazil, having begun in the late 1980s. However, the country has the potential of being a large world producer of high quality pollen, particularly because of the great diversity of tropical flora and the resistance of the Brazilian Apis mellifera bee races. Thirty-six samples of bee pollen from the Southern region of Brazil were analyzed regarding pollen types and physicochemical and nutritional composition. Only one sample was considered monofloral, which was exclusively composed by pollen from the Asteraceae family). The State of Parana showed a greater variety of pollen types, 18 in total, representing 82% of the total number identified in this study. The bee pollen in the States of Rio Grande do Sul and Parana showed a higher number of samples with humidity content above the standard permitted by the Brazilian legislation, i.e. over 4%. The bee pollen was characterized by its high protein content with average values of 20.47%. The analysis regarding humidity, lipids and sugar showed no statistical differences among the samples (p<0.05). The pollen samples had a high concentration of reducible sugars (48%). The predominant minerals in the samples PR, SC and RS were phosphorus (7102.29, 6873.40, 6661.73 mg/kg of pollen), followed by potassium (5383.73, 4997.77, 4773.26 mg/kg of pollen), calcium (1179.05, 961.93, 848.36 mg/kg of pollen) and magnesium (818.02, 679.01, 725.89 mg/kg of pollen). Statistical analysis (Tukey test) demonstrated no significant difference between the contents of calcium, copper, iron, phosphorus and sodium in the pollen samples of the South of Brazil. However, the samples from the State of Parana contained the highest contents of potassium and differed statistically from the samples of the State of Rio Grande do Sul.

Purification and Characterization of a Trypsin Inhibitor from Plathymenia foliolosa Seeds

A novel trypsin inhibitor (PFTI) was isolated from Plathymenia foliolosa (Benth.) seeds by gel filtration chromatography on a Sephadex G-100, DEAE-Sepharose, and trypsin-Sepharose columns. By SDS-PAGE, PFTI yielded a single band with a M(r) of 19 kDa. PFTI inhibited bovine trypsin and bovine chymotrypsin with equilibrium dissociation constants (K(i)) of 4 x 10(-8) and 1.4 x 10(-6) M, respectively. PFTI retained more than 50% of activity at up to 50 degrees C for 30 min, but there were 80 and 100% losses of activity at 60 and 70 degrees C, respectively. DTT affected the activity or stability of PFTI. The N-terminal amino acid sequence of PFTI showed a high degree of homology with various members of the Kunitz family of inhibitors. Anagasta kuehniella is found worldwide; this insect attacks stored grains and products of rice, oat, rye, corn, and wheat. The velvet bean caterpillar (Anticarsia gemmatalis) is considered the main defoliator pest of soybean in Brazil. Diatraea saccharalis, the sugar cane borer, is the major pest of sugar cane crops, and its caterpillar-feeding behavior, inside the stems, hampers control. PFTI showed significant inhibitory activity against trypsin-like proteases present in the larval midguts on A. kuehniella and D. saccharalis and could suppress the growth of larvae.

Characterization of fungal soil communities by F-RISA and arbuscular mycorrhizal fungi from Araucaria angustifolia forest soils after replanting and wildfire disturbances

The Fungal Ribosomal Intergenic Spacer Analysis (F-RISA) was used to characterize soil fungal communities from three ecosystems of Araucaria angustifolia from Brazil: a native forest and two replanted forest ecosystems, one of them with a past history of wildfire. The arbuscular mycorrhizal fungi (AMF) infection was evaluated in Araucaria roots of 18-month-old axenic plants previously inoculated with soils collected from those areas in a greenhouse experiment. The principal component analysis of F-RISA profiles showed different soil fungal community between the three studied areas. Sixty three percent of F-RISA fragments amplified in the soil and the substrate samples presented lengths between 500 and 700 bp. The number of Operational Taxonomic Units (OTUs) was 34 for soil and 38 for substrate, however, more fragments were detected in soil (214) than in substrate (163). An in silico F-RISA analysis to compare our data with ITS1-5.8S-ITS2 sequences from NCBI database showed the presence of Ascomycota, Basidiomycota and Glomeromycota among the soil and substrate fungal communities. AMF infection was higher in plants inoculated with soil from the native forest and the replanted forest with wildfire, both presenting similar chemical characteristics but with different disturbance levels. These results indicate that soil chemical composition may influence the soil fungal community structures rather than the anthropogenic or fire disturbances.

Characterization of nicosulfuron availability in aged soils

Sorption-desorption interactions of pesticides with soil determine their availability for transport, plant uptake, and microbial degradation. These interactions are affected by the physical-chemical properties of the pesticide and soil, and for some pesticides, their residence time in the soil. This research evaluated changes in sorption/availability of nicosulfuron (2-[[[[(4,6-dimethoxy-2-pyrimidinyl]aminolcarbonyl]amino]sulfonyl]-N,N-dimethyl-3-pyridinecarboxamide) herbicide with aging in different soils, using a radiolabeled (C-14) tracer. Aging significantly increased sorption. For instance, after the 41-day incubation, calculated K-d,K-app increased by a factor of 2 to 3 in Mollisols from the Midwestern United States and by a factor of 5 to 9 in Oxisols from Brazil and Hawaii, as compared to freshly treated soils. In view of this outcome, potential transport of nicosulfuron would be overpredicted if freshly treated soil Kd values were used to predict transport. The fact that the nicosulfuron solution concentration decreased faster than the soil concentration with time suggested that the increase in sorption was because the rate of degradation in solution and on labile sites was faster than the rate of desorption of the neutral species from the soil particles. It may have also been due to nicosulfuron anion diffusion to less accessible sites with time, leaving the more strongly bound neutral molecules for the sorption characterization. Regardless of the mechanism, these results are further evidence that increases in sorption during pesticide aging should be taken into account during the characterization of the sorption process for mathematical models of pesticide degradation and transport.

Physical and sensory characterization of coffee produced in the topoclimatic conditions at Jesuitas, Parana State (Brazil)

Climatic variations influence formation and maturation of coffee grains by altering their intrinsic characteristics, which call allow for several types of coffee qualities, including the potential for production of special coffee. This study was carried out to verify the effect of environmental conditions and crop cultivation on chemical composition and their consequences in cup quality of coffees from region of Jesuitas, Parana State. During the same crop season this study was accomplished (2002-2003), cup quality was evaluated among the producers in several coffee-growing municipalities in Parana State. It was observed that 86% of samples were classified simply as ""soft"" (smooth flavor) or ""hard"" (bolder flavor), and 14% were classified as rioysh/rio (strong unpleasant taste). The results concluded that the practices adopted by producers, who have collaborated with the study, reflected positively oil the final cup quality, when compared to the overall quality results in the State. The climatic conditions and practices of crop management and harvest ill the Jesuitas region made for bolder coffee with low acidity, comparable to high quality coffees produced in Brazil and abroad.

Cloning and characterization of transcripts differentially expressed in the pulp of ripening papaya

Papaya (Carica papaya) is a relevant tropical crop and physico-chemical changes take place very quickly, as a consequence of activation of biochemical pathways by de nova synthesis of several proteins. Thus, in order to have information on the changes in gene expression in ripening papaya, transcripts from the pulp of unripe and ripe fruit were profiled by differential-display RT-PCR (DDRT-PCR). Seventy transcript derived fragments (TDFs) isolated from gels were re-amplified by PCR and differential expression of 40 papaya genes was confirmed by reverse northern blotting. Twenty-nine positively cloned TDFs were sequenced, and 17 were putatively identified by homology search. Ten of these genes were downregulated during ripening and UDP-glucose glucosyltransferase, alpha-2 importin, RNase L inhibitor-like protein, and a syntaxin protein were identified. Among the up-regulated genes there was a carboxylesterase, an integral membrane Yip1 family protein, a glycosyl hydrolase family-like protein and an endopolygalacturonase. Considering their relatedness to papaya quality, the fragments of genes potentially implicated in carbohydrate metabolism and pulp softening may be considered of interest for further studies. According to the results, differential display was a feasible approach to investigate differences in gene expression during fruit ripening, and can provide interesting information about those fruits whose genomic data is scarce, as is the case of papayas. (c) 2009 Elsevier B.V. All rights reserved.

Prospective ultramorphological characterization of human hair by optical coherence tomography

Background/purpose The continuous advancement in cosmetic science has led to an increasing demand for the development of non-invasive, reliable scientific techniques directed toward claim substantiation, which is of utmost relevance, to obtain data regarding the efficacy and safety of cosmetic products. Methods In this work, we used the optical coherence tomography (OCT) technique to produce in vitro transversal section-images of human hair. We also compared the OCT signal before and after chemical treatment with an 18% w/w ammonium thioglycolate solution. Results The mean diameter of the medulla was 29 +/- 7 mu m and the hair diameter was 122 +/- 16 mu m in our samples of standard Afro-ethnic hair. A three-dimensional (3D) image was constructed starting from 601 cross-sectional images (slices). Each slice was taken in steps of 6.0 mu m at eight frames per second, and the entire 3D image was constructed in 60 s. Conclusion It was possible to identify, using the A-scan protocol, the principal structures: the cuticle, cortex and medulla. After chemical treatment, it was not possible to identify the main structures of hair fiber due to index matching promoted by deleterious action of the chemical agent.

Biochemical and biophysical characterization of lysozyme modified by PEGylation

PEGylation is a strategy that has been used to improve the biochemical properties of proteins and their physical and thermal stabilities. In this study, hen egg-white lysozyme (EC 3.2.1.17; LZ) was modified with methoxypolyethylene glycol-p-nitrophenyl carbonate (mPEG-pNP, MW 5000). This PEGylation of LZ produced conjugates that retained full enzyme activity with glycol chitosan, independent of degree of enzyme modification; its biological activity with the substrate Micrococcus lysodeikticus was altered according to its degree of modification. The conjugate obtained with a low degree of mPEG-pNP/NH(2) modification was studied by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF), demonstrating a spectral peak at m/z 19,988 Da with 77% of its original enzymatic activity. Spectroscopic studies of Fourier transform infrared (FIR) and circular dichroism (CD) did not show any relevant differences in protein structure between the native and conjugate LZ. Studies of the effects of pH and temperature on PEGylated LZ indicated that the conjugate was active over a broad pH range, stable at 50 degrees C, and demonstrated resistance to proteolytic degradation. (C) 2010 Elsevier B.V. All rights reserved.

Characterization of Brazilian lager and brown ale beers based on color, phenolic compounds, and antioxidant activity using chemometrics

BACKGROUND: Epidemiological studies have shown that beer has positive effects on inhibiting atherosclerosis, decreasing the content of serum low-density lipoprotein cholesterol and triglycerides, by acting as in vivo free radical scavenger. In this research, the antioxidant activity of commercial Brazilian beers (n = 29) was determined by the oxygen radical absorbance capacity (ORAC) and 1,1 -diphenyl-2-picrylhydrazyl (DPPH(center dot)) assays and results were analyzed by chemometrics. RESULTS: The brown ale samples (n = 11) presented higher (P < 0.05) flavonoids (124.01 mg L(-1)), total phenolics (362.22 mg L(-1)), non-flavonoid phenolics (238.21 mg L(-1)), lightness (69.48), redness (35.75), yellowness (55.71), color intensity (66.86), hue angle (59.14), color saturation (0.9620), DPPH(center dot) values (30.96% inhibition), and ORAC values (3,659.36 mu mol Trolox equivalents L(-1)), compared to lager samples (n = 18). Brown ale beers presented higher antioxidant properties (P < 0.05) measured by ORAC (1.93 times higher) and DPPH (1.65 times higher) compared to lager beer. ORAC values correlated well with the content of flavonoids (r = 0.47; P = 0.01), total phenolic compounds (r = 0.44; P < 0.01) and DPPH (r = 0.67; P < 0.01). DPPH values also correlated well to the content of flavonoids (r = 0.69; P < 0.01), total phenolic compounds (r = 0.60; P < 0.01), and non-flavonoid compounds (r = 0.46; P = 0.01). CONCLUSION: The results suggest that brown ale beers, and less significantly lager beers, could be sources of bioactive compounds with suitable free radical scavenging properties. (C) 2010 Society of Chemical Industry

Characterization of interactions between polyphenolic compounds and human serum proteins by capillary electrophoresis

The interaction of ten natural polyphenolic compounds (chlorogenic acid, apigenin, catechin, epicatechin, flavanone, flavone, quercetin, rutin, vicenin-2 and vitexin) with human serum albumin and mixtures of human serum albumin and alpha(1)-acid glycoprotein under near physiological conditions is studied by capillary electrophoresis-frontal analysis. Furthermore, the binding of these polyphenolic compounds to total plasmatic proteins is evaluated using ultrafiltration and capillary electrophoresis. In spite of the relatively small differences in the chemical structures of the compounds studied, large differences were observed in their binding behaviours to plasmatic proteins. The hydrophobicity, the presence/absence of some functional groups, steric hindrance and spatial arrangement seem to be key factors in the affinity of natural polyphenols towards plasmatic proteins.

Structural characterization of exopolysaccharides from biofilm of a cariogenic streptococci

Soluble (EPS-SOL), as well as insoluble extracellular polysaccharide (EPS-INSOL), extracted from biofilm of Streptococcus mutans, were analyzed by nuclear magnetic resonance spectroscopy, methylation analysis, and a controlled Smith degradation. EPS-SOL was a branched alpha-glucan containing a (1 -> 6)-and (1 -> 3)-linkages. EPS-INSOL was a branched alpha-glucan with similar linkages, but with a (1 -> 3)-linked main-chain partially substituted at O-6 with Glcp-(1 -> 6)-Glcp-side chains. Biofilm EPS had a distinct chemical structure compared with those synthesized by plankton cells or by purified enzymes from S. mutans, which could indicate different mechanisms for its degradation. (C) 2011 Published by Elsevier Ltd.