Mercury and selenium concentrations in hair samples of women in fertile age from Amazon riverside communities

The aim of the present study was to evaluate mercury and selenium concentrations in hair samples of reproductive age women from riverside communities of the Tapajós River basin. We studied 19 pregnant and 21 non-pregnant women, 13 to 45 years old, living in the region for at least 2 years, and having a diet rich in fish. The analysis of Se and total Hg were performed in the Instituto de Pesquisas Energéticas e Nucleares (IPEN, S?o Paulo, Brazil) by using a Varian AA220-FS atomic absorption spectrometer with a flow injection system. There were no differences between the two groups - pregnant and non-pregnant -- concerning age (23.80 +/- 6.92 and 26.60 +/- 9.60 years old, respectively) and residential time (20.21 +/- 8.30 and 22.20 +/- 10.90 years, respectively). The geometric means and ranges for total Hg concentration were similar (p > 0.05): 8.25 microg/g (1.51-19.43) in pregnant and 9.39 microg/g (5.25-21.00) in non-pregnant women, respectively. Total Hg concentrations were also similar in different gestational stages. However, there was a significant difference between the two groups (p < 0.05, Student t test) in relation to Se concentration: 0.61 microg/g (0.40-2.33) in pregnant and 2.46 microg/g (0.92-5.74) in non-pregnant women, respectively. We concluded that Hg exposure levels in reproductive age women were only slightly higher than a provisional tolerable weekly intake of MeHg would provide, that Hg concentration in maternal hair samples was independent of gestational age, and that low Se concentration in pregnant women indicates high mineral consumption by fetal organism to satisfy their metabolic requirements raised during pregnancy, including as a protective mechanism for Hg cytotoxic effects.     

Generation and Progress Behavior of Strain-Induced Abnormally Large Grains in Superalloy 718

Metallurgical and Materials Transactions A - Herein, the behavior associated with strain-induced abnormally large grains in superalloy 718 was investigated using compression testing and subsequent...     

Randomized Controlled Trial of Darbepoetin α Versus Continuous Erythropoietin Receptor Activator Injected Subcutaneously Once Every Four Weeks in Patients with Chronic Kidney Disease at the Pre-Dialysis Stage

Continuous erythropoietin receptor activator (CERA) seems to maintain a stable hemoglobin (Hb) level because its half-life is longer than darbepoetin α (DA). Twenty chronic kidney disease (CKD) patients at the pre-dialysis stage who had been administered DA for over 24 weeks were randomly assigned to receive subcutaneous CERA or DA once every four weeks during 48 weeks. In both groups, the rate of achievement of target Hb level changed from 70% to 100% in weeks 0 to 48, with no significant difference between the groups. Compared with week 0, the Hb level was significantly increased from week 24 in the DA group and from week 8 in the CERA group. In addition, the reticulocyte count was significantly increased from week 4 in the CERA group compared with the DA group. There was no significant difference in the levels of estimated glomerular filtration rate and iron status between both groups. Because of the small number of patients in this study, only limited conclusions can be drawn. However, the results suggest that subcutaneous administration of DA or CERA once every four weeks to predialysis patients has similar effects on achievement of target Hb levels.     

Reversible polycolour change of viologens from violet through transparent to white

The electrochromic properties of 1,1′-dibenzyl-4,4′-bipyridinium and 1,1′-diheptyl-4,4′-bipyridinium were investigated in the presence of MBr (M = Li⁺, Na⁺, and K⁺). The cyclic voltammograms of these viologens showed a white-coloured state in addition to the usual violet one-electron reduction state and the colourless divalent state. Chemical analyses (FT-IR and XPS spectra) of the white film and some control experiments with different supporting electrolytes, MX (X = Cl⁻ and I⁻), revealed that the viologens formed water-insoluble ion pairs with tribromide generated by the electrooxidation of monobromide to produce a white film. The film was reversibly decolourized electrochemically to the initial transparent state, providing the polyelectrochromism using the simple viologen/MBr systems. The colouration efficiencies for the violet and the white-coloured states were 170 cm²/C and 104 cm²/C, respectively.     

Novel preparation method of highly active Co/SiO2 catalyst for Fischer-Tropsch synthesis with chelating agents

Co/SiO₂ catalysts were prepared by the incipient wetness method using the aqueous Co nitrate solution modified with various organic acids and/or chelating agents followed by drying and calcination. After H₂ reduction at 773 K, the catalyst prepared with nitrilotriacetic acid (NTA) showed Fischer-Tropsch synthesis (FTS) activity ca. 3 times higher than the catalyst without additives under mild reaction conditions (503 K, 1.1 MPa).     

Electrolysis of LiOH for hydrogen supply

The hydrolysis of lithium hydride (LiH) is a promising technique for the supply of hydrogen. LiH can be stored in sealed tanks or cartridges of ∼6% mass effective hydrogen capacity. However, the lack of an efficient recycling method for the byproduct lithium hydroxide (LiOH) has been a limitation to its use. Here, we propose and demonstrate a recycling process based on the hot melt electrolysis of a LiOH–LiCl eutectic mixture at 380 °C. The electrolysis activation potential was measured at 3.08 V. Lithium production was observed around the cathode using differential scanning calorimetry (DSC) and cyclic voltametry. Current efficiency was estimated 37.9%, and the absence of LiCl decomposition was confirmed.     

Development of Co-Cr-based longitudinal magnetic recording media:Thermodynamic consideration

This paper reviews our recent work on development of Co-Cr-based longitudinal magnetic recording media through the point of view of thermodynamics. It focuses on our experimental finding on the miscibility gap in the fcc α-Co phase region of the Co-Cr binary system, and on the predictions on the improvements of magnetic properties of many Co-Cr-Z ternary systems by thermodynamic computing on the basis of the newly-assessed Co-Cr binary thermodynamic parameters. Good agreement in the phase separation behavior of many Co-Cr-Z (Z=Pt, Ta, Ge)alloy systems between the calculation and the experiments has been achieved, as discussed in detail in the full paper.By the same token, many other elements, such as Ir, P, B, Mo, Zr, Nb, have been predicted to improve the magnetic grain isolation of the potential Co-Cr-Z multicomponent magnetic recording media in the future.     

New designs and simulations of a 10-kW average-power longitudinally pumped dye laser amplifier

New designs of a 10-kW average-power longitudinally pumped dye laser amplifier pumped by a copper laser and its operating simulations are presented. The new designs, which use a center-hole mirror, make it possible to pump longitudinally without dichroic mirrors. The simulations take into consideration the time-dependent excited-state absorption of both the laser and the pump beam. Dye laser amplifiers, with an input dye laser average power of 10 kW, are simulated. The simulation results suggest that a better than 50% extraction efficiency can be obtained with two pump beams of more than 1 kW. The results also suggest that an amplified gain of 10 with an extraction efficiency of approximately 50% can be obtained with the double-pass amplifier.