Study of the oxidation kinetics of finely-divided magnetites. II - Influence of chromium substitution

The oxidation kinetics of magnetites substituted by chromium (Fe²⁺Fe³⁺_2?xCr³⁺_x)O^2?₄ (0 < x < 2) into γ(Fe³⁺_1?yCr³⁺_y)₂O^2?₃, (x = 3y), which is a metastable phase, was found out to be ruled by the law of diffusion, under variable working conditions, of vacancies generated at the surface. The chemical diffusion coefficient is a function of the substitution ratio, crystallite size and the number of vacancies in the spinel lattice. Contrary to magnetites substituted by aluminum, the activation energy varies irregularly with the substitution ratio.     

The Beck Depression Inventory and Research Diagnostic Criteria: Congruence in an Older Population.

This study examined the congruence between conventional cutoff scores on the Beck Depression Inventory (BDI) and selected diagnostic classifications of the Research Diagnostic Criteria in a sample of 102 elders seeking psychological treatment. Only 16.67% were misclassified by customary BDI cutoff scores. Minor Depressive Disorders were less clearly identified than Major Depressive Disorders or nondepressed status. Similar results were obtained in a second sample of elders not seeking treatment. Findings support the utility of the BDI as a screening instrument for identification of clinically depressed elders. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Efficiency in water quality control for the Wilamette River

The Federal Water Pollution Control Act of 1972, P.L. 92-500, requires tertiary treatment of all effluent by 1983; Oregon State policy focuses on maintaining future effluent discharges at a level no greater than current levels. The Federal and State policies are combined in planning for the future management of the quality of the Willamette River. As a consequence, the Willamette will be clean-too clean- and the economic inefficiency inherent in the water quality control plan will cause misallocation of public resources. This misallocation could be avoided by incorporating economic principles, especially cost comparisons and the consideration of alternative procedures, into the water quality plan.     

Solid-solution partitioning of Cd, Cu, Ni, Pb, and Zn in the organic horizons of a forest soil

We report the solid-liquid partitioning of Cd, Cu, Ni, Pb, and Zn in 60 organic horizon samples of forest soils from the Hermine Watershed (St-Hippolyte, PQ, Canada). The mean Kd values are respectively 1132, 966, 802, 3337 and 561. Comparison of those Kd coefficients to published compilation values show that the Kd values are lower in acidic organic soil horizons relative to the overall mean Kd values compiled for mineral soils. But, once normalized to a mean pH of 4.4, the Kd values in organic soil horizons demonstrate the high sorption affinity of organic matter, which is either as good as or up to 30 times higher than mineral soil materials for sorbing trace metals. Regression analysis shows that, within our data set, pH and total metal contents are not consistent predictors of metal partitioning. Indeed, metal sorption by the solid phase must be studied in relation to complexation by dissolved organic ligands, and both processes may sometime counteract one another.     

Electron-beam treatment of aromatic hydrocarbons that can be air-stripped from contaminated groundwater. 2. Gas-phase studies

The electron-beam (EB) degradation of volatile aromatics (benzene, toluene, ethylbenzene, xylenes: BTEX) in groundwater strip gas, which in the present work has been modeled by the introduction of the desired aromatic(s) to a stream of air or another gas, such as oxygen, is initiated essentially by the addition of *OH radicals to the aromatic ring, giving rise to hydroxycyclohexadienyl radicals, which form the corresponding peroxyl radicals upon addition of oxygen. As studied in some detail with benzene as a BTEX representative, various reactions of these lead to numerous oxidation products in a cascade of reactions, including the decomposition of products under the prevailing conditions of high turnover of the initial aromatic. Importantly, hydroxycyclohexadienylperoxyl radical formation is partly reversible, and the reactions of the hydroxycyclohexadienyl radicals, which thus have a significant presence in these systems, must therefore also be taken into consideration. In the gas phase, in contrast to the aqueous phase (see Part 1), the reactions of the hydroxycyclohexadienyl radicals lead to oligomeric products that appear to contribute, in addition to ionic clusters, to nucleation for the aerosols observed. Various nitrated products, among them nitrophenols, are observed when air is used for the stripping. However, these studies did not clear the pilot plant stage, since BTEX degradation using a bioreactor carried out in parallel was so successful that the EB technology was judged to be noncompetitive. As for the latter, expensive equipment consisting of a stripper, the EB machine, and an aerosol precipitator would be required. The condensed aerosols are biorefractory and would require further treatment for detoxification.     

Packet Reservation Window Multiple Access for Microcellular Voice/Data Transmission

We propose a new packet reservation multiple access (PRMA) scheme for the joint transmission of voice and data traffics in a microcellular medium. The collision resolution protocol within the system is based on a modification of the window random access algorithm, which has superior properties compared to the conventional slotted Aloha. The proposed algorithm, which we call packet reservation window multiple access (PRWMA), works in distinct modes for voice and data without prioritization, and the user performs slightly different operations depending on the information type. Simulation results show that PRWMA outperforms PRMA by a significant margin in terms of voice user capacity.     

Design of FLC for high-angle-of-attack flight using adaptive evolutionary algorithm

In this paper, a new methodology of evolutionary computations - An Adaptive Evolutionary Algorithm (AEA) is proposed. AEA uses a genetic algorithm (GA) and an evolution strategy (ES) in an adaptive manner in order to take merits of two different evolutionary computations : global search capability of GA and local search capability of ES. In the reproduction procedure, the proportions of the population by GA and ES are udaptively modulated according to the fitness. AEA is used for designing fuzzy logic controller (FLC) for a high-angle-of-attack flight system for a super-maneuverable version of F-18 aircraft. AEA is used to determine the membership functions and scaling factors of an FLC. The computer simulation results show that the FLC has met both robustness and performance requirements.     

Convective-diffusion-based fluorescence correlation spectroscopy for detection of a trace amount of E. coli in water

Fluorescence correlation spectroscopy (FCS) is adapted for a new procedure to detect trace amounts of Escherichia coli in water. The present concept is based on convective diffusion rather than Brownian diffusion and employs confocal microscopy as in traditional FCS. With this system it is possible to detect concentrations as small as 1.5 x 10(5) E. coli per milliliter (2.5 x 10(-16) M). This concentration corresponds to an approximately 1.0-nM level of Rhodamine 6G dyes. A detailed analysis of the optical system is presented, and further improvements for the procedure are discussed.     

In vivo measurement of the brain and skull resistivities using an EIT-based method and realistic models for the head

In vivo measurements of equivalent resistivities of skull (rho(skull)) and brain (rho(brain)) are performed for six subjects using an electric impedance tomography (EIT)-based method and realistic models for the head. The classical boundary element method (BEM) formulation for EIT is very time consuming. However, the application of the Sherman-Morrison formula reduces the computation time by a factor of 5. Using an optimal point distribution in the BEM model to optimize its accuracy, decreasing systematic errors of numerical origin, is important because cost functions are shallow. Results demonstrate that rho(skull)/rho(brain) is more likely to be within 20 and 50 rather than equal to the commonly accepted value of 80. The variation in rho(brain)(average = 301 omega x cm, SD = 13%) and rho(skull)(average = 12230 omega x cm, SD = 18%) is decreased by half, when compared with the results using the sphere model, showing that the correction for geometry errors is essential to obtain realistic estimations. However, a factor of 2.4 may still exist between values of rho(skull)/rho(brain) corresponding to different subjects. Earlier results show the necessity of calibrating rho(brain) and rho(skull) by measuring them in vivo for each subject, in order to decrease errors associated with the electroencephalogram inverse problem. We show that the proposed method is suited to this goal.     

Contribution of epididymal secretory proteins for spermatozoa maturation

The final stages of sperm differentiation occur outside the gonad and are not under the genomic control of germ cells. Only sequential interactions with the medium surrounding the sperm are believed to induce the final steps of spermatogenesis. The epididymis, a long tubule with very active secretory and reabsorption functions, is able to create sequential changes in the composition of luminal fluid throughout its length. The chronologies of the changes, which occur on/in the sperm with those in their surrounding environment, are described. Correlations between the highly regionalized epididymal activities and sperm characteristics linked to their survival and fertility potential are presented in this review.