Morphological analysis of poly(o-methoxyaniline) thin-films deposited by spin coating technique

Morphological study of conducting polymer thin films obtained by spin coating is reported. Poly(o-methoxyaniline) films were deposited onto glass substrates and analyzed by profilometry and atomic force microscopy (AFM). It is shown that final thickness is correlated by a power law with spin speed with a solution concentration varying coefficient and that surface roughness decreases with increasing spin speed.     

Substance use as a robust correlate of school outcome measures for ethnically diverse adolescents of Asian/Pacific Islander ancestry.

School psychologists are generally not provided with the knowledge and skills to address both educational and psychosocial issues of Asian American and Pacific Islander students. The present study is the first of its kind in examining 36 independent (i.e., demographic, social, cultural, psychological) variables in association with four school outcomes (i.e., grade point average, absences, suspensions, and school infractions) with a large sample of Caucasian, Filipino, Native Hawaiian, Japanese, mixed/non-Hawaiian, and "other" Hawai'i high school students (N = 2,833). Given the relatively unique sample in question and the sheer number of variables, an exploratory approach was utilized with the goal of determining the most robust independent variables, with the unique inclusion of Hawaiian cultural identification. A cross-validation technique was used, whereby stepwise regressions were performed for each of two cross-validation samples; only common variables were retained in a final stepwise model for each of the four school outcomes. The results indicated that, remarkably, substance use accounted for the most variance (i.e., 8.4% -16.1 %) in the four school measures. Further analyses detailed the relationship, including the finding that smoking cigarettes regularly, accounted for the most variance compared to the other five substance use items. Further research and implications of the findings are discussed, including the need for prevention and intervention programs that incorporate substance use as a component, both within and outside of school environments. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

UPGRADING OF SUGAR CANE BAGASSE BY THERMAL PROCESSES. 5. CHARACTERIZATION OF THE OILS OBTAINED FROM COAL CO-PROCESSING WITH SUGARCANE BAGASSE OIL

In the present work, the chemical characterization of the oils obtained from liquefaction of different coals with sugar cane bagasse oil and also from the liquefaction of coal with monoethanolamine are presented. Characterization of the oil samples was done with the add of spectroscopic and chromatographic techniques, including UV-vis, FTIR, NMR, preparative liquid chromatography (PLC) and high resolution gas chromatography (HRGC).     

Simultaneous HPLC quantification of total cholesterol,tocopherols and β-carotene in Barrosã-PDO veal

A simple, rapid and sensitive procedure for the simultaneous determination of total cholesterol, tocopherols and β-carotene in meat is described. The method involves a direct saponification of the meat, a single n-hexane extraction and the analysis of the extracted compounds by normal-phase HPLC, using fluorescence (tocopherols) and UV–Vis photodiode array (cholesterol and β-carotene) detections in tandem. Rates of recovery of spiked meat samples were 93% for cholesterol, 83–86% for (α-, β- and -γ) tocopherols and 89% for β-carotene. Repeatabilities were high (CV < 6%) for all determined compounds, except for δ-tocopherol. This tocopherol, which is not usually present in meat, showed a much lower recovery percentage (73%) and repeatability (12.8%). This methodology was applied for the quantification of total cholesterol, tocopherols and β-carotene in three muscles (longissimus thoracis, longissimus lumborum and semitendinosus) of the Portuguese traditional Barrosã-PDO veal, obtained from autochthonous calves fed extensively during summer (with the least abundant green pastures) and slaughtered in early autumn (October). Barrosã-PDO veal showed median contents of total cholesterol (0.50–0.56 mg/g) and, depending on the analysed muscle, moderate to high contents of α-tocopherol (3.3–3.9 μg/g) and β-carotene (0.07–0.09 μg/g), suggesting an high sensorial and hygienic quality.     

Influence of pencil lead hardness on voltammetric response of graphite reinforcement carbon electrodes

This work studied the voltammetric response of graphite reinforcement electrodes made of different pencil lead hardness. The studies showed that harder graphite leads, regardless of their manufacturer, are more appropriate as electrode material for voltammetric purposes due to their higher peak currents, increasing sensitivity and reproducibility, with ΔEp closer to the theoretical value for a reversible system.     

Genotoxic effect of Physalis angulata L. (Solanaceae) extract on human lymphocytes treated in vitro

Physalis angulata L (Solanaceae) is a medicinal plant from North of Brazil, whose different extracts and infusions are commonly used in the popular medicine for the treatment of malaria, asthma, hepatitis, dermatitis and rheumatism. However, the genotoxic effects of P. angulata on human cells is not well known. The main purpose of the present study was to evaluate the in vitro genotoxic effects of aqueous extract of P. angulata using the comet assay and the micronucleus assay in human lymphocytes provided from 6 healthy donors. Treatments with P. angulata extracts were performed in vitro in order to access the extent of DNA damage. The comet assay has shown that treatments with P. angulata at 0.5, 1.0, 2.0, 3.0 and 6.0 microg/mL in culture medium were genotoxic. Lymphocytes treated with P. angulata at the concentrations of 3.0 and 6.0 microg/mL in culture medium showed a statistically significant increase in the frequency of micronucleus (p<0.05), however, the cytokinesis blocked proliferation index (CBPI) was not decreased after P. angulata treatment. In conclusion, the present work demonstrated the genotoxic effects of P. angulata extract on human lymphocytes in vitro.     

Biology and pathology of Schistosoma mansoni and Schistosoma japonicum infections in several strains of nude mice

Schistosoma mansoni and S. japonicum infections in nude mice (nu/nu) were compared with infections in nu/+ heterozygotes or intact mice. Seven to 12 weeks after exposure to S. mansoni, the responses of Swiss NCR, C3H, BALB/c and C57B1/6 nude mice did not differ substantially. Nude mice of all these strains showed minute granulomas around eggs in the liver and minimal hepatic fibrosis. Microvesicular and necrotizing changes in hepatocytes were similar in all mouse strains, and S. mansoni infections were frequently lethal to nude, but not to intact mice between the seventh and ninth weeks of infection. Nude mice that survived the ninth week of infection generally lived until the 12th week. The number of eggs per mature worm pair in the tissues of S. mansoni-infected nude mice was similar to the number in intact mice, but nude mice passed fewer eggs in the feces. Nude mice that received serum from infected intact mice excreted eggs in the stool in numbers equivalent to intact mice, but continued to form minute granulomas around S. mansoni eggs. Reconstitution with fetal thymus or with splenocytes from normal or S. mansoni-infected mice partially or completely restored hepatic granuloma size, granuloma eosinophils, hepatic fibrosis, and excretion of eggs in the feces. In contrast to S. mansoni infection, S. japonicum infections in nude mice did not cause necrosis of hepatocytes or excessive mortality, and S. japonicum eggs were passed in the feces in numbers equivalent to those passed by infected intact mice.     

Viscometric and transmitted light investigation of agarose and agarose-guar water systems

Summary Agarose water solutions of different concentrations and agarose-guar water solutions of 1% (w/w) total concentration and varied compositions were submitted to viscometric and turbidimetric measurements as function of the temperature. Phase diagrams for both systems are compared. For agarose solutions, phase separation occurs prior to gelation within a certain concentration range, and network formation seems to take place by the connectivity of the polymer-rich domains. For the mixed agarose-guar system, the homogeneous solutions gel directly.     

Production of single and multi-walled carbon nanotubes using natural gas as a precursor compound

In this work, the Catalytic Chemical Vapor Deposition (CCVD) technique was used to synthesize carbon nanotubes (CNT). Natural gas (NG) was employed as a carbon source for the growing of CNT, while magnesium oxide was used as a catalyst support for the nanotubes synthesis. Two systems were utilized. The Fe–Mo/MgO system was obtained by the impregnation technique through the dispersion of iron oxide, which is the catalyst, over magnesia (with molybdenum additions). This system was tested intending to optimize the parameters for the production of single-walled carbon nanotubes (SWCNT). Moreover, Mg_1−x Fe _x MoO₄, which was prepared by the combustion synthesis method, was tested to produce multi-walled carbon nanotubes (MWCNT). The Fe-Mo/MgO tests were carried out under H₂/GN and Ar/GN atmospheres at 950 °C, whereas the Mg_1−x Fe _x MoO₄ was submitted to 1,000 °C under H₂/GN atmosphere. The Fe–Mo/MgO catalyst produced better results regarding number of CNT and their diameters under Ar/NG atmospheres than under H₂/NG atmospheres. The system Mg_1−x Fe _x MoO₄ produced MWCNT according to the expectations.     

Factors controlling cracking of concrete affected by reinforcement corrosion

The present paper tries to contribute to quantifying the relationship between the amount of corrosion and cover cracking. The variables studied were: cover/diameter (c/ø), proportions of cement, w/c, cast position of the bar, transverse reinforcement and corrosion rate. The corrosion is accelerated by applying constant currents causing the rebar to act as an anode. The results indicate that the cracking process develops in two steps: generation and propagation. Radius losses of about 15–50 μm are necessary to generate the first visible crack (<0.1 mm width). The propagation follows a behaviour of the type: w (crack width in mm)=a+bx (radius loss in μm).