Total and acid-soluble fluoride content of infant cereals, beverages and biscuits from Brazil

Total fluoride (TF) and HCl 0.01 M ('gastric juice')-soluble fluoride (SF) were analysed in infant foods, beverages and calcium-rich biscuits. Samples were divided into seven categories: children cereals (A), chocolate-flavoured milk (B), soy beverages (C), filled biscuits (D), non-filled biscuits (E), wafer biscuits (F) and corn starch biscuits (G). Mean TF concentrations ± SD (amplitude, unit µg F ml^-1 or µg F g^-1) were: (A) 4.25 ± 3.04 (0.20 - 7.84, n = 6); (B) 0.34 ± 0.47 (0.05-1.27, n = 6); (C) 0.15 ± 0.07 (0.09-0.29, n = 8); (D) 8.44 ± 1.76 (7.65-10.47, n = 4); (E) 12.41 ± 1.15 (10.69-13.68, n = 4); (F) 0.35 ± 0 (0.34-0.36, n = 4) and (G) 7.77 ± 1.12 (6.86-8.68, n = 2). Five samples of cereals, one sample of chocolate-flavoured milk and 10 samples of biscuits were analysed for SF. In cereals analysed for SF, all fluoride was soluble, while for the chocolate-flavoured milk, approximately 50% of TF was soluble. Regarding the biscuits analysed for SF approximately 20% of TF was soluble. It was observed that some of the cereals and beverages, and most of the biscuits analysed, might be important contributors to total daily fluoride intake. When consumed just once per day, cereals and beverages might supply up to 25% of the maximum recommended daily fluoride intake (0.07 mg F kg^-1 body weight) for a 2-year-old child (12 kg). For the filled, non-filled and corn starch biscuits, when 3, 32 or 20 units of them, respectively, are consumed just once per day, they may supply up to 16% of the maximum recommended daily fluoride intake. However, only approximately 25% of fluoride absorption occurs from the stomach and 75% from the small intestine. Therefore, a higher fluoride bioavailability is possible.     

Predicting the dynamic behavior of axial-field actuators

A method is presented for predicting the dynamic behavior of axial-field actuators. This method entails the numerical solution of a system of nonlinear differential equations that govern the dynamics. The theory is applied to a specific actuator geometry, and the predicted results are compared with empirical data     

Electronic Structure and Free-Energy Relationships for Some 4′-Substituted 4-Dimethylamino trans-Stilbenes by U.V. Photoelectron Spectroscopy

A Series of 4′-subsituted 4-dimethylamino trans-stilbenes 1-5 was investigated by UPS, in connection with conjugated donor-acceptor substituted double bond photochemistry. The measured and assigned spectra indicate a high sensitivity, depending on the changed electronic structure by 4′-substituents of compounds 1-5 . Correlation of ionization energies in LFE-relationship with Hammett's σ_p-values and other ground state data was proved, demonstrating UPS a powerful tool for substituent effect studies in conjugated double bond systems.     

Synthesis and characterization of geopolymers containing blends of unprocessed steel slag and metakaolin: The role of slag particle size

The present research deals with the production and characterization of geopolymers prepared by mixing metakaolin with a steel slag from the production of chromium-manganese steel, a commercial sodium silicate solution and a sodium hydroxide solution. Different specimens were prepared by mixing metakaolin with different proportions of steel slag (20, 40, 60, 80 wt%) characterized by different maximum particle size. Specimens containing just metakaolin and steel slag alone were also prepared for comparison. All specimens have been characterized regarding their compressive strength, specific surface area, water absorption and microstructure. It has been observed that the use of fine steel slag powders leads to increases the performances and that the specimens containing 40 wt% steel slag and 60 wt% metakaolin revealed the best overall behaviour.     

Polarography of tetrahedral halogeno-complexes of transition metals in dimethylformamide

The polarographic behaviour of tetrahedral MX₄²⁻ complexes (M = Mn, Fe, Co, Ni, Zn; X = Cl, Br, I) has been investigated in dimethylformamide, where such complex anions are reduced at much more negative potentials than the corresponding octahedral solvates, the only exception being Ni. Polarographic data afford evidence for increasing stability of the tetrahalogeno complexes in the order I < Br < Cl. Co-ordination number of the investigated metals ions towards halides is never observed to exceed 4. Easier reducibility of Ni²⁺ in chloride media allows sharp Ni/Co and Ni/Fe separations.     

Studies on the effects of phosphine on Salmonella enterica serotype Enteritidis in culture medium and in black pepper (Piper nigrum)

The effect of phosphine on Salmonella enterica serotype Enteritidis inoculated in culture medium and in black pepper grains (Piper nigrum), as well as on the reduction of the microbial load of the dried and moisturized product, was verified. The postfumigation effect was verified in inoculated samples with 0.92 and 0.97 water activity (a(w)) exposed to 6 g/m(3) phosphine for 72 h, dried to 0.67 a(w), and stored for 24, 48, and 72 h. No decreases were observed in Salmonella Enteritidis populations in culture medium when fumigant concentrations up to 6 g/m(3) were applied for 48 h at 35°C. However, the colonies showed reductions in size and atypical coloration as the phosphine concentration increased. No reduction in Salmonella counts occurred on the inoculated dried samples after fumigation. On the other hand, when phosphine at concentrations of 6 g/m(3) was applied on moisturized black pepper for 72 h, decreases in Salmonella counts of around 80% were observed. The counts of total aerobic mesophilic bacterium populations of the dried and moisturized black pepper were not affected by the fumigant treatment. The results of the postfumigation studies indicated that Salmonella Enteritidis was absent in the fumigated grains after drying and storage for 72 h, indicating a promising application for this technique. It was concluded that for Salmonella Enteritidis control, phosphine fumigation could be applied to black pepper grains before drying and the producers should rigidly follow good agricultural practices, mainly during the drying process, in order to avoid product recontamination. Additional work is needed to confirm the findings with more Salmonella serotypes and strains.     

A three-dimensional field solution for permanent-magnet axial-fieldmotors

A formula is presented for computing the field in axial-field permanent-magnet motors. The formula is based on a three-dimensional (3-D) analytical analysis and is expressed in terms of a finite sum of elementary functions. It is readily programmed and ideal for parametric studies of field strength. It is also well suited for parallel processing and could be developed into a motor model for real-time performance simulations. It is applied here to a practical motor geometry and verified by the use of 3-D finite element analysis (FEA)     

Formulas for the force and torque of axial couplings

Closed-form expressions are presented for computing the force and torque that is transmitted by synchronous axial couplings. These expressions enable rapid parametric studies of coupling performance relative to the selection of magnet material, dimensions, and spacings. They are also useful for testing three-dimensional numerically based field algorithms. The derived expressions are tested here using data taken from a ceramic coupling     

Polycyclic aromatic hydrocarbons (PAHs) in sugarcane juice

Sugarcane juice is a common beverage in many Brazilian cities. At harvesting season most sugarcane plantation is burnt and this procedure has been shown as an important source of PAHs emission. In the present study 80 samples of sugarcane juice collected from two Brazilian cities, in two different periods, were analysed for the presence of four PAHs: benz(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene and benzo(a)pyrene. PAHs were detected in 50% of the samples. The samples collected between harvests presented mean sums of PAHs of 0.013 μg/kg and 0.012 μg/kg, while the samples collected during harvest presented mean sums of 0.053 μg/kg and 0.055 μg/kg. A higher concentration and incidence of PAHs in the juices collected in the harvest period was verified, corroborating the burning of the crops as a source of sugarcane juice contamination.