The impact of cleaner processing on nutrient availability in the bleached kraft industry.

The pulp and paper industry has invested heavily over recent years in cleaner processing, to reduce losses and minimise its impact on the environment. Over the past fifteen years, a New Zealand integrated bleached kraft mill has undergone a comprehensive programme of upgrades to increase production, reduce water consumption and streamline its biological treatment process. Whilst the overall discharge of contaminants from the site decreased, the treatment system performance did not show a concurrent improvement as may have been expected. Reduced BOD removal, low dissolved oxygen levels, and poor solids settlability were symptomatic of phosphorus limitation in the aerated lagoon treatment system. The wastewater entering the system was found to be phosphorus limited at a BOD:P ratio of 100:0.2. Mono-ammonium-phosphate was supplemented, at approximately 30 kg P/d, to raise the phosphorus levels to a BOD:P ratio of 100:0.3. Treatment efficiencies improved very quickly after phosphorus dosage, with a 50% reduction in BOD and TSS discharge, a significant increase in dissolved oxygen levels, and improved BOD removal (85% to 93%). This case study demonstrates that whilst more closed operation can result in reduced discharge of organic loads, there may be negative impacts on the availability of nutrients for balanced biological growth.     

Simulation of contact stresses and forces during hot rolling of thin wide strips with allowance for a stick zone and elastic regions in the deformation zone

A new procedure for the calculation of contact stresses and hot-rolling forces for wide strips 0.8–1.5 mm thick has been developed and tested. This procedure takes into account the presence of a stick zone in the deformation zone and stress distributions in both elastic and plastic regions in the deformation zone. The average error in the force calculation according to the new procedure is 5%, which is more than two times smaller than the calculation error of well-known force calculation procedures. The developed procedure is used to simulate the contact stresses in the deformation zones of working stands in a six-stand 1700 mill during rolling of strips thinner than 1.0 mm. A number of new relations for the state of stress in a strip have been revealed upon simulation. Some of these relations are as follows: in the last stands, the length of elastic regions accounts for 10–17% of the total deformation-zone length; the maximum normal contact stresses are 1300–1400 MPa, which corresponds to the stresses in the deformation zones of cold-rolling mills; the stick-zone length accounts for 85–99% of the deformation-zone length; and the contact stresses in the stick zone are virtually independent of the friction coefficient. The developed calculation procedure can be used to optimize the technological regimes of wide-strip mills.     

Life history of Teretriosoma nigrescens Lewis (Coleoptera: Histeridae) and its ability to suppress populations of Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae)

The life history and behaviour of Teretriosoma nigrescens Lewis are typical of a histerid predator, but only 2, instead of the expected 3, larval instars were recorded. At 27°C, 70% r.h. development from oviposition to adult emergence took about 8 weeks. In 24 h at 27°C, 70% r.h., T. nigrescens adults and larvae, respectively, consumed on average up to 1.7 and 3.5 Prostephanus truncatus (Horn) larvae. After 7 weeks, 10 T. nigrescens adults prevented populations of 25, 50, 75 and 100 P. truncatus from increasing, while controls increased at least 10-fold. Grain moisture contents of between 8.5–14% had little effect on predatory efficiency.     

Oxydation catalytique des phenols par le peroxyde d'hydrogene: Etude structurale des catalyseurs Fe/Al2O3 et Fe-Cu/Al2O3 par spectroscopie Mossbauer

This study recalls the results obtained on the oxidation by hydrogen peroxide of a number of hydroxyl aromatic compounds with alumina supported catalysts and more particularly the structural study of these catalysts. The catalysts were prepared under different conditions: without thermic treatment, by oxidation in air at 450°C and by thermic reduction at 500 and 700°C, under hydrogen flow. The structural study by Mössbauer spectroscopy of the catalysts Fe/Al₂O₃ and Fe-Cu/Al₂O₃ made it possible to specify in what form was found the iron, as a function of the conditions under which the catalysts were prepared. For the catalyst prepared by impregnation without thermic treatment the iron on the support was in hematite form (α-Fe₂O₃) well crystallized in small particles with 10–20% iron which could be ferric ions (Fe³⁺) chemically adsorbed on alumina or iron within the structure of the alumina (Figs 7 and 8). Thermic oxidation in air brought about the appearance of hematite in the form of large particles (Fig. 9) whereas the thermic reduction under hydrogen flow led to the formation of crystallized metallic iron (α-Fe) (Fig. 12). The reducibility of iron on the support increased with the increase in temperature of reduction and with the presence of copper (Figs 11 and 13). As for the activity of the different catalysts in oxidation reactions of phenols by hydrogen peroxide, we notice that whatever the form of the catalyst, the activity was more important for pyrocatechol than for phenol (Fig. 3). As far as stability of the metals on the support was concerned, during the oxidation reaction we noticed that it was greater with an oxidized catalyst than with a reduced one (Figs 4 and 5). The comparison between the results obtained in a batch and in a continuous reactor made it possible to show that the first phase of the reaction was probably due to the superposition of the phenomena of homogeneous (by the Fe ions passed into solution) and heterogeneous catalysts (Fig. 6). The comparative structural study reduced before and after use was quite in agreement with the solubilization of iron that we observed during oxidation (Figs 15 and 13). However on the oxidized catalyst hematite was not modified after use and the most significant change on the spectrum was a slight decrease of E_Q (0.1 mm s^?1) in the central doublet (Figs 14 and 9).     

Use of laser interferometers for measuring displacements of the surfaces of tested objects

A mathematical model and the results of the numerically simulated procedures of measuring displacements of tested objects’ surfaces with the use of laser interferometers are presented. Promising measurement techniques are substantiated, and recommendations for their use are given.     

Transition From Perturbed to Coupled-Cavity Behavior With Asymmetric Spectral Emission in Ridge Lasers Emitting at 1.55 μm

We have investigated a series of ridge waveguide lasers with deeply etched slots in the ridges. The slots do not penetrate the active region, but are deep enough to strongly perturb the longitudinal modes. By the addition of slots, a transition between perturbed-mode and coupled-cavity behavior is crossed. With a group of four or more slots, the below-threshold amplified spontaneous emission spectrum from each end of the laser has different periods and the facet-facet oscillations are suppressed indicating that the different sections have become quasi-independent. A model using a distributed emitter in the cavity reproduces this behavior. Above threshold, the single contact coupled cavity lasers are single mode with greater than 30-dB sidemode suppression ratio over a wide range of currents     

Formation of cube texture in nickel-palladium alloys for epitaxial substrates for deposition of high-temperature superconductors

The texture, structure, and magnetic and mechanical properties of thin ribbons of nickel-palladium alloys have been studied. It has been demonstrated that in Ni₉₄Pd₆ and Ni_92.5Pd₅W_2.5 alloys, a sharp cube texture can be formed that is stable up to rather high annealing temperatures. Segregation of palladium atoms to surface layers of ribbons has been found, which gives additional advantages for using these ribbons as substrates for epitaxial deposition of high-temperature superconductors.