Effect of Glycerol and Sisal Nanofiber Content on the Tensile Properties of Corn Starch/Sisal Nanofiber Films.

Currently, petroleum-derived plastics are widely used despite the disadvantage of their long degradation time. Natural polymers, however, can be used as alternatives to overcome this obstacle, particularly cornstarch. The tensile properties of cornstarch films can be improved by adding plant-derived nanofibers. Sisal (Agave sisalana), a very common low-cost species in Brazil, can be used to obtain plant nanofibers. The goal of this study was to obtain sisal nanofibers using low concentrations of sulfuric acid to produce thermoplastic starch nanocomposite films. The films were produced by a casting technique using commercial corn starch, glycerol, and sisal nanofibers, accomplished by acid hydrolysis. The effects of glycerol and sisal nanofiber content on the tensile mechanical properties of the nanocomposites were investigated. Transmission electron microscopy findings demonstrated that the lowest concentration of sulfuric acid produced fibers with nanometric dimensions related to the concentrations used. X-ray diffraction revealed that the untreated fibers and fibers subjected to acid hydrolysis exhibited a crystallinity index of 61.06 and 84.44%, respectively. When the glycerol and nanofiber contents were 28 and 1%, respectively, the tensile stress and elongation were 8.02 MPa and 3.4%. In general, nanocomposites reinforced with sisal nanofibers showed lower tensile stress and higher elongation than matrices without nanofibers did. These results were attributed to the inefficient dispersion of the nanofibers in the polymer matrix. Our findings demonstrate the potential of corn starch nanocomposite films in the packaging industry.

Dry extrusion pretreatment of cassava starch aided by sugarcane bagasse for improved starch saccharification.

The enzymatic hydrolysis of native starch lacks efficiency because starch is mostly confined in semi-crystalline granules. To address the challenges associated with gelatinization and render native cassava starch (CS) amenable to enzymatic hydrolysis (enzyme cocktail from Aspergillus awamori and Trichoderma reesei), dry-extrusion pretreatment of CS mixed with sugarcane bagasse (SB) was studied. Results showed that among the CS:SB mass ratios studied (1:1; 1:0.5 and 1:0.25), extruded CS:SB (1:0.25) gave the highest 3-hour glucose yield (71.5%) after enzymatic hydrolysis. Extrusion reduced CS:SB (1:0.25) crystallinity by 78% and increased the intensity of all major FTIR absorption bands by 67-202%. The optimum 3-hour glucose yield from extruded CS:SB (1:0.25) hydrolysis was 74.1%, which was 330% higher than from untreated CS. The water absorption and solubility indices of the treated biomass increased by 145% and 12,640%, respectively under the optimum conditions, aiding the hydrolysis process. The dry extrudates were easy to manipulate and store.

Effect of the interleukin-1B gene on serum oxidized low-density lipoprotein levels.

OBJECTIVES: To investigate the association of the +3953 IL-1B gene polymorphism in healthy subjects with serum oxidized LDL (oxLDL) levels. DESIGN AND METHODS: We selected 255 subjects who were non-smokers and who had no cardiovascular or other chronic degenerative diseases, and we measured the oxLDL and other glucose levels, lipid biomarkers and biological variables that are related to cardiovascular metabolism. The +3953 IL-1B gene polymorphism was determined using molecular genetics techniques (PCR-RFLP). RESULTS: A significant association among the +3953 IL-1B genotypes and the oxLDL level was observed. The TT genotype presented lower oxLDL levels than the other genotypes. A multivariate analysis showed that this result was independent of the sex, age, obesity and hypertension status of the subjects. CONCLUSIONS: Our results suggest that the IL-1B gene polymorphism affects the modulation of serum oxLDL levels.

The relationship between the levels of stress and the age and years of service of military firefighters from the fire rescue corps of the metropolitan area of the state of São Paulo.

PURPOSE: To verify the relationship between stress indicators and the age and years of service of military firefighters from the fire rescue corps of the metropolitan area of the state of São Paulo. METHODS: Forty military firefighters with the mean age of 37.9 ± 5.4 years, from the 1st, 2nd and 8th fire brigades of the metropolitan area of São Paulo participated in this study. All underwent clinical, physical and psychological evaluations to verify the relationship between the age and years of service with the variables of levels of stress (tension, depression, anger, vigor, fatigue, confusion and total stress) on workdays and on days off. RESULTS: On workdays, the mean scores for tension, depression, fatigue and stress were overall higher compared to those on days off. The older the firefighter, the higher the levels of stress, depression, anger and total stress. The more years of service, the greater the depression and anger. CONCLUSIONS: The levels of stress were high on workdays. Chronological age and years of service influenced the increase in the scores of stress.