Rheology and flow of phosphate slurries (mine tailings) in pipes

An experimental study of the flow of phosphate mine tailings was carried out in order to characterize these suspensions of fine particles for pipeline transport. Rheological measurements with a rotating cylinder viscometer indicate a viscoplastic behaviour which can be represented by a Herschell-Bulkley or by a Casson model. The variation of the parameters of these models with solids concentration reveals a change in the behaviour at a concentration of 10 to 15%. The pressure drops were measured during flow in capillary tubes, in both laminar and turbulent regimes. The variation of the pressure drop coefficient (Fanning friction factor) as a function of the generalized Reynolds number confirms the validity of the employed rheological models. The results are in good agreement with measurements made in pipes of industrial size. The velocity profiles measured with a novel ultrasonic velocimeter demonstrate the influence of the rheological behaviour on the yield and wall stresses.     

Oxidation of organosulfur compounds by hydrogen peroxide in the presence of niobium and vanadium peroxo complexes

New niobium(V) peroxo complexes containing aspargine and Schiff base ligands were synthesized, and their structures were solved by IR, NMR, and mass spectrometric methods. They were found to be catalytically active for the peroxidation of methyl phenyl sulfide and benzothiophene to the corresponding sulfoxide and sulfones. It was shown that vanadium(V) peroxo complexes with the same ligands are less active in the oxidation of methyl phenyl sulfide than the niobium complexes.     

Long-Term Biological Effects of Very Intense 60 Hz Electric Field on Mice

This paper presents the results of long-term exposure of mice to a 240 kV/m, 60 Hz electric field. Both males and females were subjected to this very intense field for over 4500 h before they were sacrificed for tests. The progenies resulting from breeding the various couples were also exposed to the same field. Studies were made to determine the effects of the electric field on drinkdng water consumption, rate of growth, body weight, number of progenies bom and survived, blood count and blood chemistry, protein analysis, and organs histology. In each study, the results were compared with those obtained from the corresponding control group.     

Repair of damaged aluminum truss joints of highway overhead sign structures using FRP

An innovative repair technique is introduced for aluminum truss-type highway overhead sign structures, using fibre-reinforced polymer (FRP) sheets. The welded k-joints are typically subjected to excessive fatigue-induced cracking under the effects of wind and moving traffic. The repair technique proposed in this paper utilizes longitudinal FRP layers bonded to the diagonals and wrapped around the main chord to form alternating v-patterns, followed by additional circumferential layers for anchorage. Eight tests were conducted on four full-scale specimens. Weld lines at the junction between diagonals and main chord were ground to simulate a 90% loss of joint strength. After repair, diagonals were loaded to failure in tension. The study showed that full strength of the welded joints was restored using carbon-FRP sheets. Only 70% of joint strength was restored when using glass-FRP. The strengthening technique is particularly sensitive to quality control during installation. A field application using the proposed technique was successfully completed by the New York State Department of Transportation for a cracked aluminum truss over Route 88 in NY State.     

Fabrication of single- and multilayer MoS2 film-based field-effect transistors for sensing NO at room temperature

Single- and multilayer MoS(2) films are deposited onto Si/SiO(2) using the mechanical exfoliation technique. The films were then used for the fabrication of field-effect transistors (FETs). These FET devices can be used as gas sensors to detect nitrous oxide (NO). Although the single-layer MoS(2) device shows a rapid response after exposure to NO, the current was found to be unstable. The two-, three-, and four-layer MoS(2) devices show both stable and sensitive responses to NO down to a concentration of 0.8 ppm.     

Gout in the elderly. Clinical presentation and treatment

Types and distribution patterns of glycoconjugates in antral ovarian follicles were investigated in the buffalo, using periodic-acid Schiff (PAS), high iron diamine (HID), low ion diamine (LID) and lectin histochemical staining methods. HID and LID staining procedures were preceded in some cases by digestion with testicular hyaluronidase, Streptomyces hyaluronidase, chondroitinase ABC and heparitinase (heparinase III). Lectin staining was performed with the use of 12 horseradish peroxidase (HRP) lectin conjugates. Some lectin staining procedures were preceded by neuraminidase digestion and saponification. Large amounts of isomeric chondroitin sulphates and a minor quantity of heparan sulphate and hyaluronic acid and/or chondroitin were found in follicular fluid. Lectin staining of buffalo follicular fluid revealed glycoconjugates with different glucidic determinants such as beta-N-acetylgalactosamine, beta-galactose-(1-3)-N-acetylgalactosamine, beta-galactose-(1-4)-N-acetylglucosamine, N-acetylglucosamine, alpha-fucose and alpha-glucose/alpha-mannose, and sialic acid residues. Glycosaminoglycans were absent in the zona pellucida of oocytes in small antral follicles. Acidic glycoconjugates in the zona pellucida were caused by sulphated groups and sialic acid residues. Our data show few internal glucidic residues, such as N-acetylglucosamine in the buffalo zona pellucida but many subterminal beta-N-acetylgalactosamine, alpha- and beta-galactose determinants masked by sialic acids. These findings demonstrate that buffalo follicular fluid has a very heterogeneous composition that is similar to that found in small and large bovine follicles. No differences in composition of the follicular fluid were observed in the follicles examined.     

Automatic classification of multiple signals using 2D matching of magnitude–frequency density features

Signal classification is an important function of modern communication systems in software defined radio applications. The ability to quickly recognize the type of received signals allows a system to automatically adapt the processor to properly decode the signals. Many classification techniques assume that the received signal space is occupied by only one signal, and that the frequency of operation is known. However, in some systems, the receiver may be completely blind to the number and characteristics of signals within the bandwidth of interest. The technique introduced in this study proposes the collapsing of localized magnitude peaks from consecutive short time discrete fourier transform bins into magnitude histograms to create a two dimensional image of the frequency?Cmagnitude density of the received signal space. This image can be a useful visualization tool in the characterization of the signal space in user assisted modes of classification. Alternatively, the process could be automated by utilizing pattern recognition and image processing algorithms. Automatic signal classification is explored in this study.     

Relationship Between Grain Hardness and Malting Quality of Barley (Hordeum vulgare L.)

In a three‐year period, protein content, polysaccharides and values of the selected malting parameters were determined in 12 varieties of barley. Hardness was assessed using the particle size index (PSI) and a Do‐Corder apparatus (BRA). Significant differences in the levels of hardness between the varieties were detected. Hardness was affected by variety from 37% (PSI) and 71% (BRA). Significant correlations were determined between the PSI and extract content (0.64^***), Kolbach index (0.66^***), friability (0.57^***), β‐glucans in wort (?0.51^***) and colour of malt (0.57^***). Significant correlations were found between BRA and content of non‐starch polysaccharides in caryopses (0.64^***), extract (?0.62^***), Kolbach index (?0.70^***), friability (?0.70^***), β‐glucans in wort (0.79^***) and wort colour (?0.56^***). Correlation was determined between hardness and malting quality index (PSI 0.51^***, BRA ?0.71^***).     

Drilling in mudrocks: rock behavior issues

Borehole stability analyses use different analytical models to evaluate stresses, pressures, and temperatures around boreholes. Mudrocks do not possess spatio-temporally constant material properties: mechanical properties are time-dependent because of the continuous change in pore pressure, moisture content, and temperature near the borehole. Mudrocks with high specific surface areas also exhibit high sensitivity to changes in physical and chemical properties of their pore fluids. Pressure and concentration diffusion during drilling continuously change the ionic composition of pore fluids and, accordingly, the engineering properties of those fine-grained argillaceous materials. Such fine-grained materials are considered “reactive”; it is shown that a “reactivity coefficient” can be used to assess the physico-chemical sensitivity of mudrocks. Coupling between chemical and mechanical properties may develop in reactive mudrocks, leading to further changes in their mechanical parameters. Experimental data from triaxial and oedometer tests are presented for several materials to illustrate their time-dependent mechano-chemical properties in borehole environments. A discussion of coupled diffusivity processes in mudrocks is included, and the concept of large micro-scale strains that can lead to deterioration of properties is introduced.Finally, we speculate on the degree of complexity required for constitutive modeling of borehole stability analysis of shales in practical situations.