On-line analysis of froth surface in coal and mineral flotation using JKFrothCam

The personal computer revolution has resulted in the widespread availability of low-cost image analysis hardware. At the same time, new graphic file formats have made it possible to handle and display images at resolutions beyond the capability of the human eye. Consequently, there has been a significant research effort in recent years aimed at making use of these hardware and software technologies for flotation plant monitoring. Computer-based vision technology is now moving out of the research laboratory and into the plant to become a useful means of monitoring and controlling flotation performance at the cell level. This paper discusses the metallurgical parameters that influence surface froth appearance and examines the progress that has been made in image analysis of flotation froths. The texture spectrum and pixel tracing techniques developed at the Julius Kruttschnitt Mineral Research Centre are described in detail. The commercial implementation, JKFrothCam, is one of a number of froth image analysis systems now reaching maturity. In plants where it is installed, JKFrothCam has shown a number of performance benefits. Flotation runs more consistently, meeting product specifications while maintaining high recoveries. The system has also shown secondary benefits in that reagent costs have been significantly reduced as a result of improved flotation control. (C) 2002 Elsevier Science B.V. All rights reserved.

The ethics of germ line gene manipulation - A five dimensional debate

Contributors to the debate surrounding the ethics of germ line gene manipulation have by and large concentrated their efforts on discussions of the potential risks that are associated with the use of this technology. Many international advisory committees have ruled out the acceptability of germ line gene manipulation at least for the time being. The purpose of this work is to generate much needed discussion on the many other ethical issues concerning the implementation of not only germ line gene manipulation but also other related biotechnologies. In this paper I systematically investigate and analyse the most salient issues put forward by proponents and opponents alike. I argue that if germ line manipulation proves to be a safe and effective procedure, then the principle of beneficence imposes on the medical profession a moral duty to pursue the technology.

Shoot control of hypernodulation and aberrant root formation in the har1-1 mutant of Lotus japonicus

The har1-1 mutant of Lotus japonicus B-129-S9 Gifu is characterized by two phenotypes: greater than normal nodulation (hypernodulation) and significantly inhibited root growth in the presence of its microsymbiont Mesorhizobium loti strain NZP2235. We demonstrate that the two traits co-segregate, suggesting a single genetic alteration involving developmental pleiotropy. A cross between the mutant and genotype Funakura (with wild-type root and nodule morphology) demonstrated Mendelian recessive segregation of both phenotypes (root and nodule) in 216 F2 individuals. Using DNA-amplification fingerprinting polymorphisms in Gifu har1-1 and Funakura, the mutant locus was positioned between two markers at about 7 and 13 cM distance. Reciprocal hypocotyl grafting of shoots and roots showed that the hypernodulation and reduced root phenotypes are both predominantly controlled by the shoot.

Development of a novel titration and off-gas analysis (TOGA) sensor for study of biological processes in wastewater treatment systems

The development of the new TOGA (titration and off-gas analysis) sensor for the detailed study of biological processes in wastewater treatment systems is outlined. The main innovation of the sensor is the amalgamation of titrimetric and off-gas measurement techniques. The resulting measured signals are: hydrogen ion production rate (HPR), oxygen transfer rate (OTR), nitrogen transfer rate (NTR), and carbon dioxide transfer rate (CTR). While OTR and NTR are applicable to aerobic and anoxic conditions, respectively, HPR and CTR are useful signals under all of the conditions found in biological wastewater treatment systems, namely, aerobic, anoxic and anaerobic. The sensor is therefore a powerful tool for studying the key biological processes under all these conditions. A major benefit from the integration of the titrimetric and off-gas analysis methods is that the acid/base buffering systems, in particular the bicarbonate system, are properly accounted for. Experimental data resulting from the TOGA sensor in aerobic, anoxic, and anaerobic conditions demonstrates the strength of the new sensor. In the aerobic environment, carbon oxidation (using acetate as an example carbon source) and nitrification are studied. Both the carbon and ammonia removal rates measured by the sensor compare very well with those obtained from off-line chemical analysis. Further, the aerobic acetate removal process is examined at a fundamental level using the metabolic pathway and stoichiometry established in the literature, whereby the rate of formation of storage products is identified. Under anoxic conditions, the denitrification process is monitored and, again, the measured rate of nitrogen gas transfer (NTR) matches well with the removal of the oxidised nitrogen compounds (measured chemically). In the anaerobic environment, the enhanced biological phosphorus process was investigated. In this case, the measured sensor signals (HPR and CTR) resulting from acetate uptake were used to determine the ratio of the rates of carbon dioxide production by competing groups of microorganisms, which consequently is a measure of the activity of these organisms. The sensor involves the use of expensive equipment such as a mass spectrometer and requires special gases to operate, thus incurring significant capital and operational costs. This makes the sensor more an advanced laboratory tool than an on-line sensor. (C) 2003 Wiley Periodicals, Inc.

Differential requirements for COPI coats in formation of replication complexes among three genera of Picornaviridae

Picornavirus RNA replication requires the formation of replication complexes (RCs). consisting of virus-induced vesicles associated with viral nonstructural proteins and RNA. Brefeldin A (BFA) has been shown to strongly inhibit RNA replication of poliovirus but not of encephalomyocarditis virus (EMCV). Here, we demonstrate that the replication of parechovirus 1 (ParV1) is partly resistant to BFA, whereas echovirus 11 (EV11) replication is strongly inhibited. Since BFA inhibits COPI-dependent steps in endoplasmic reticulum (ER)-Golgi transport, we tested a hypothesis that different picornaviruses may have differential requirements for COPI in the formation of their RCs. Using immunofluorescence and cryo-immunoelectron microscopy we examined the association of a COPI component, beta-COP, with the RCs of EMCV, ParV1, and EV11 EMCV RCs did not contain beta-COP. In contrast, beta-COP appeared to be specifically distributed to the RCs of EV11 In ParV1-infected cells beta-COP was largely dispersed throughout the cytoplasm, with some being present in the RCs. These results suggest that there are differences in the involvement of COPI in the formation of the RCs of various picornaviruses, corresponding to their differential sensitivity to BFA. EMCV RCs are likely to be formed immediately after vesicle budding from the ER, prior to COPI association with membranes. ParV1 RCs are formed from COPI-containing membranes but COPI is unlikely to be directly involved in their formation, whereas formation of EV11 RCs appears to be dependent on COPI association with membranes.

The radiation chemistry of ultem at 77 K as revealed by ESR spectroscopy

Radical formation in ultem following gamma-radiolysis has been reassessed, and the G(R*) values at different temperatures have been determined by ESR spectroscopy. The radical assignment and radical reactivity have been re-examined by photobleaching and thermal annealing studies. Photobleachable radical anions were found to comprise approximate to40% of the total number of radicals formed on radiolysis at 77 K. Spectral subtraction methods, ESR spectral simulations, measurement of g-values and the hyperfine splitting constants were used to identify the other radical intermediates. The principal chain scission radicals are formed due to scission of the main-chain at (i) the ether linkage, (ii) the isopropylidene group and (iii) the imide ring in the main chain. The side chain methyl groups of the isopropylidine units also lose hydrogen to form methylene radicals. The five-line spectrum observed to decay in the temperature range 370-430 K, which has not been assigned previously, has been identified as being characteristic of a di-substituted benzyl radical. (C) 2002 Elsevier Science Ltd. All rights reserved.

Petrology and geochemistry of the Bandas del Sur Formation, Las Canadas Edifice, Tenerife (Canary Islands)

The Bandas del Sur Formation preserves a Quaternary extra-caldera record of central phonolitic explosive volcanism of the Las Canadas volcano at Tenerife. Volcanic rocks are bimodal in composition, being predominantly phonolitic pyroclastic deposits, several eruptions of which resulted in summit caldera collapse, alkali basaltic lavas erupted from many fissures around the flanks. For the pyroclastic deposits, there is a broad range of pumice glass compositions from phonotephrite to phonolite. The phonolite pyroclastic deposits are also characterized by a diverse, 7-8-phase phenocryst assemblage (alkali feldspar + biotite + sodian diopside + titanomagnetite + ilmenite + nosean-hauyne + titanite + apatite) with alkali feldspar dominant, in contrast to interbedded phonolite lavas that typically have lower phenocryst contents and lack hydrous phases. Petrological and geochemical data are consistent with fractional crystallization (involving the observed phenocryst assemblages) as the dominant process in the development of phonolite magmas. New stratigraphically constrained data indicate that petrological and geochemical differences exist between pyroclastic deposits of the last two explosive cycles of phonolitic volcanism. Cycle 2 (0.85-0.57 Ma) pyroclastic fall deposits commonly show a cryptic compositional zonation indicating that several eruptions tapped chemically, and probably thermally stratified magma systems. Evidence for magma mixing is most widespread in the pyroclastic deposits of Cycle 3 (0.37-0.17 Ma), which includes the presence of reversely and normally zoned phenocrysts, quenched mafic glass blebs in pumice, banded pumice, and bimodal to polymodal phenocryst compositional populations. Syn-eruptive mixing events involved mostly phonolite and tephriphonolite magmas, whereas a pre-eruptive mixing event involving basaltic magma is recorded in several banded pumice-bearing ignimbrites of Cycle 3. The periodic addition and mixing of basaltic magma ultimately may have triggered several eruptions. Recharge and underplating by basaltic magma is interpreted to have elevated sulphur contents (occurring as an exsolved gas phase) in the capping phonolitic magma reservoir. This promoted nosean-hauyne crystallization over nepheline, elevated SO3 contents in apatite, and possibly resulted in large, climatologically important SO2 emissions.

Multiple shoot formation in lentil (Lens culinaris) seeds

A protocol based on seed culture was developed for efficient in vitro propagation of lentil (Lens culinaris Medik). Benzyladenine (BA), thidiazuron (TDZ), and kinetin all induced multiple shoot formation. In terms of the number of long shoots (>2.0 cm) produced per seed, BA and TDZ at optimum concentrations (0.2-0.4 and 0.1 mg/litre, respectively) had similar efficiency, whereas kinetin produced less shoots. Murashige and Skoog (MS) salt composition was better than that of Gamborge (B5) for shoot induction. Increasing calcium (Ca) concentration was necessary to overcome shoot-tip necrosis. For shoot elongation, fresh medium of the same composition of shoot induction medium could be used for stumps from medium with low BA (

Hepatic covalent adduct formation with zomepirac in the CD26-deficient mouse

Background and Aims: Zomepirac (ZP), a non-steroidal anti-inflammatory drug (NSAID), has been reported to cause immune-mediated liver injury. In vivo, ZP is metabolized to a chemically reactive acyl glucuronide conjugate (ZAG) which can undergo covalent adduct formation with proteins. Such acyl glucuronide-derived drug-protein adducts may be important in the development of immune and toxic responses caused by NSAID. We have shown using immunoabsorptions that the 110 kDa CD26 (dipeptidyl peptidase IV) is one of the hepatic target proteins for covalent modification by ZAG. In the present study, a CD26-deficient mouse strain was used to examine protein targets for covalent modification by ZP/metabolites in the liver. Methods and Results: The CD26-deficient phenotype was confirmed by immunohistochemistry, flow cytometry analysis, RT-PCR, enzyme assay and immunoblotting. Moreover, by using monoclonal antibody immunoblots, CD26 was not detected in the livers of ZP-treated CD26-deficient mice. Immunoblots using a polyclonal antiserum to ZP on liver from ZP-treated mice showed three major sizes of protein bands, in the 70, 110 and 140 kDa regions. Most, but not all, of the anti-ZP immunoreactivity in the 110 kDa region was absent from ZP-treated CD26-deficient mice. Conclusion: These data definitively showed that CD26 was a component of ZP-modified proteins in vivo. In addition, the data suggested that at least one other protein of approximately 110 kDa was modified by covalent adduct formation with ZAG. (C) 2002 Blackwell Science Asia Pty Ltd.

Modelling of microstructure formation and evolution during solidification

A comprehensive probabilistic model for simulating microstructure formation and evolution during solidification has been developed, based on coupling a Finite Differential Method (FDM) for macroscopic modelling of heat diffusion to a modified Cellular Automaton (mCA) for microscopic modelling of nucleation, growth of microstructures and solute diffusion. The mCA model is similar to Nastac's model for handling solute redistribution in the liquid and solid phases, curvature and growth anisotropy, but differs in the treatment of nucleation and growth. The aim is to improve understanding of the relationship between the solidification conditions and microstructure formation and evolution. A numerical algorithm used for FDM and mCA was developed. At each coarse scale, temperatures at FDM nodes were calculated while nucleation-growth simulation was done at a finer scale, with the temperature at the cell locations being interpolated from those at the coarser volumes. This model takes account of thermal, curvature and solute diffusion effects. Therefore, it can not only simulate microstructures of alloys both on the scale of grain size (macroscopic level) and the dendrite tip length (mesoscopic level), but also investigate nucleation mechanisms and growth kinetics of alloys solidified with various solute concentrations and solidification morphologies. The calculated results are compared with values of grain sizes and solidification morphologies of microstructures obtained from a set of casting experiments of Al-Si alloys in graphite crucibles.

New W-isotope evidence for rapid terrestrial accretion and very early core formation

The short-lived Hf-182-W-182-isotope system is an ideal clock to trace core formation and accretion processes of planets. Planetary accretion and metal/silicate fractionation chronologies are calculated relative to the chondritic Hf-182-W-182-isotope evolution. Here, we report new high-precision W-isotope data for the carbonaceous chondrite Allende that are much less radiogenic than previously reported and are in good agreement with published internal Hf-W chronometry of enstatite chondrites. If the W-isotope composition of terrestrial rocks, representing the bulk silicate Earth, is homogeneous and 2.24 epsilon(182W) units more radiogenic than that of the bulk Earth, metal/silicate differentiation of the Earth occurred very early. The new W-isotope data constrain the mean time of terrestrial core formation to 34 million years after the start of solar system accretion. Early terrestrial core formation implies rapid terrestrial accretion, thus permitting formation of the Moon by giant impact while Hf-182 was still alive. This could explain why lunar W-isotopes are more radiogenic than the terrestrial value. Copyright (C) 2002 Elsevier Science Ltd.

Instabilities and drop formation in cylindrical liquid jets in reduced gravity

The effects of convective and absolute instabilities on the formation of drops formed from cylindrical liquid jets of glycerol/water issuing into still air were investigated. Medium-duration reduced gravity tests were conducted aboard NASA's KC-135 and compared to similar tests performed under normal gravity conditions to aid in understanding the drop formation process. In reduced gravity, the Rayleigh-Chandrasekhar Equation was found to accurately predict the transition between a region of absolute and convective instability as defined by a critical Weber number. Observations of the physics of the jet, its breakup, and subsequent drop dynamics under both gravity conditions and the effects of the two instabilities on these processes are presented. All the normal gravity liquid jets investigated, in regions of convective or absolute instability, were subject to significant stretching effects, which affected the subsequent drop and associated geometry and dynamics. These effects were not displayed in reduced gravity and, therefore, the liquid jets would form drops which took longer to form (reduction in drop frequency), larger in size, and more spherical (surface tension effects). Most observed changes, in regions of either absolute or convective instabilities, were due to a reduction in the buoyancy force and an increased importance of the surface tension force acting on the liquid contained in the jet or formed drop. Reduced gravity environments allow better investigations to be performed into the physics of liquid jets, subsequently formed drops, and the effects of instabilities on these systems. In reduced gravity, drops form up to three times more slowly and as a consequence are up to three times larger in volume in the theoretical absolute instability region than in the theoretical convective instability region. This difference was not seen in the corresponding normal gravity tests due to the masking effects of gravity. A drop is shown to be able to form and detach in a region of absolute instability, and spanning the critical Weber number (from a region of convective to absolute instability) resulted in a marked change in dynamics and geometry of the liquid jet and detaching drops. (C) 2002 American Institute of Physics.

Structural changes in mixed Langmuir-Blodgett films upon nanoparticle formation

The formation of CdS nanoparticles by reacting mixed Langmuir-Blodgett films of arachidic acid and either octadecylamine or dimethyldioctadecylammonium nitrate on a cadmium-containing subphase with hydrogen sulfide gas has resulted in the identification of a number of structural changes, observed using grazing incidence X-ray diffraction. In the case of octadecylamine, the structure after reaction is a hexagonal close-packed array of surfactant-stabilized nanoclusters, with a lattice constant of a = 17.65 Angstrom. In both octadecylamine and dimethyldioctadecylammonium nitrate films, the presence of a unit cell tilted at 38degrees to the plane of the substrate was found. Despite these changes, the average nanoparticle size was unaffected by the addition of either second component to the film.