Engineering aspects of the selective acid leaching process for refining mixed nickel-cobalt hydroxide

The precipitation of mixed hydroxide is increasingly being considered as an intermediate step in the hydrometallurgical processing of nickel and cobalt. Producers currently receive roughly 75% of the value of the contained nickel and zero value for contained cobalt. In this paper, a new selective leach process for refining the mixed hydroxide is described that allows for recovery of the majority of the nickel as final metal product and realizes value for the cobalt. The features of the new process are compared with two other alternative routes (1) acid leaching followed by solvent extraction of the cobalt and (2) ammonia leaching followed by solvent extraction of the nickel. The outcomes of a process simulation for the selective acid leaching process are presented along with capital and operating cost estimates. The operating and capital costs of the process are estimated to ±50%. For the processing of 50,000 t-Ni/y in the form of MHP, the operating cost is estimated to be $93 million AUD ($0.87 per lb of Ni contained in MHP) and the capital cost as defined for this study is estimated to be $287 million AUD. A new 20 year plant processing MHP would have a payback period of less than 2 years, an IRR of over 60$1.5 billion AUD. Over 94% of the total value (nickel and cobalt) contained in the MHP is extracted by the new process

Bone marrow aspirate microscopy v. bone marrow trephine biopsy microscopy for detection of Mycobacterium tuberculosis infection

Background. Tuberculosis (TB) remains a global health problem. According to the 2013 Global Report on  Tuberculosis, 8.6 million people developed TB in 2012 and 1.3 million died from the disease. An  estimated 13% of people who developed TB in 2012 were HIV-positive, and 75% of these lived in Africa. While pulmonary TB is the commonest form of Mycobacterium tuberculosis infection, extrapulmonary TB is increasingly being detected in HIV-positive patients. Definitive diagnosis of disseminated TB is a challenge owing to atypical presentations and diagnostic difficulties (negative chest radiograph and sputum microscopy and culture). A rapid diagnosis of disseminated TB is desirable, as early initiation of treatment can reduce mortality. Although TB culture is the gold standard for diagnosis of TB, it has a longturnaround time (up to 6 weeks).Objectives. To identify a potentially faster and more effective diagnostic strategy for disseminated TB.Methods. A retrospective 18-month review, conducted at a tertiary hospital, comparing histological findings of an auramine O-stained bone marrow aspiration (BMA) smear and a bone marrow trephine (BMT) biopsy specimen with the gold standard of TB culture.Results. Microscopic examination of BMA smears and BMT biopsy specimens offers a rapid diagnostic strategy, with results available on the same day for the former and within 4 days for the latter. BMT histological examination had a significantly higher detection rate than BMA auramine O staining compared with TB culture.Conclusion. We recommend that BMT biopsies remain an essential part of the diagnostic work-up for disseminated TB

Thermophysical and chemical characterization of charring ablative materials Final report

Thermophysical and chemical properties of charring ablative material

Variable iron-line emission near the black hole of Markarian 766

We investigate the link between ionised Fe X-ray line emission and continuum emission in the bright nearby AGN, Mrk 766. A new long (433 ks) XMM-Newton observation is analysed, together with archival data from 2000 and 2001. The contribution from ionised line emission is measured and its time variations on short (5-20 ks) timescales are correlated with the continuum emission. The ionised line flux is found to be highly variable and to be strongly correlated with the continuum flux, demonstrating an origin for the ionised line emission that is co-located with the continuum emission. Most likely the emission is ionised reflection from the accretion disc within a few A.U. of the central black hole, and its detection marks the first time that such an origin has been identified other than by fitting to spectral line profiles. Future observations may be able to measure a time lag and hence achieve reverberation mapping of AGN at X-ray energies.Comment: Accepted for publication, Astronomy and Astrophysics letter

X-ray Spectral Variability and Rapid Variability of the Soft X-ray Spectrum Seyfert 1 Galaxies Ark 564 and Ton S180

The bright, soft X-ray spectrum Seyfert 1 galaxies Ark 564 and Ton S180 were monitored for 35 days and 12 days with ASCA and RXTE (and EUVE for Ton S180). The short time scale (hours-days) variability patterns were very similar across energy bands, with no evidence of lags between any of the energy bands studied. The fractional variability amplitude was almost independent of energy band. It is difficult to simultaneously explain soft Seyferts stronger variability, softer spectra, and weaker energy-dependence of the variability relative to hard Seyferts. The soft and hard band light curves diverged on the longest time scales probed, consistent with the fluctuation power density spectra that showed relatively greater power on long time scales in the softest bands. The simplest explanation is that a relatively hard, rapidly-variable component dominates the total X-ray spectrum and a slowly-variable soft excess is present in the lowest energy channels of ASCA. Although it would be natural to identify the latter with an accretion disk and the former with a corona surrounding it, a standard thin disk could not get hot enough to radiate significantly in the ASCA band, and the observed variability time scales are much too short. The hard component may have a more complex shape than a pure power-law. The most rapid factor of 2 flares and dips occurred within ~1000 sec in Ark 564 and a bit more slowly in Ton S180. The speed of the luminosity changes rules out viscous or thermal processes and limits the size of the individual emission regions to <~15 Schwarzschild radii (and probably much less), that is, to either the inner disk or small regions in a corona

Rapid X-ray Variability of Seyfert 1 Galaxies

The rapid and seemingly random fluctuations in X-ray luminosity of Seyfert galaxies provided early support for the standard model in which Seyferts are powered by a supermassive black hole fed from an accretion disc. However, since EXOSAT there has been little opportunity to advance our understanding of the most rapid X-ray variability. Observations with XMM-Newton have changed this. We discuss some recent results obtained from XMM-Newton observations of Seyfert 1 galaxies. Particular attention will be given to the remarkable similarity found between the timing properties of Seyferts and black hole X-ray binaries, including the power spectrum and the cross spectrum (time delays and coherence), and their implications for the physical processes at work in Seyferts.Comment: To appear in From X-ray Binaries to Quasars: Black Hole Accretion on All Mass Scales, ed. T. J. Maccarone, R. P. Fender, and L. C. Ho (Dordrecht: Kluwer

THE PSOCOPTERA OF THE KRAKATAU ISLANDS, INDONESIA

At least 80 species of Psocoptera are represented in recent collections from the Krakatau Islands, Sunda Strait. They represent 15 families, and 29 species are described tu new. Twenty four species are known only from the Krahataus but. others are widespread in nearby regions of Sumatra and Java and a few are known to be more broadly distributed. Numbers of species recorded from each of the Krahatau Islands are : Rakata 58, Panjang 48, Sertung 27, Anak Krakatau 27

U-Pb Ages of Lunar Apatites

Apatite is one of the minerals that is rarely utilized in U-Pb geochronology, compared to some other U-rich accessory phases. Relatively low U concentration, commonly high proportion of common Pb and low closure temperature of U-Pb system of apatite inhibit its application as geochronological tool when other minerals such as zircon are widely available. However, zircon appear to be restricted to certain type of lunar rocks, carrying so called KREEP signature, whereas apatite (and whitlockite) is a common accessory mineral in the lunar samples. Therefore, utilizing apatite for lunar chronology may increase the pool of rocks that are available for U-Pb dating. The low stability of U-Pb systematics of apatite may also result in the resetting of the system during meteoritic bombardment, in which case apatite may provide an additional tool for the study of the impact history of the Moon. In order to investigate these possibilities, we have analysed apatites and zircons from two breccia samples collected during the Apollo 14 mission. Both samples were collected within the Fra Mauro formation, which is interpreted as a material ejected during the impact that formed the Imbrium Basin

Impacts from ice-nucleating bacteria on deep convection: implications for the biosphere-atmosphere interaction in climate change

International audienceA cloud modeling framework is described to simulate ice nucleation by biogenic aerosol particles, as represented by airborne ice-nucleation active (INA) bacteria. It includes the empirical parameterization of heterogeneous ice nucleation. The formation of cloud liquid by soluble material coated on such insoluble aerosols is represented and determines their partial removal from deep convective clouds by accretion onto precipitation. Preliminary simulations are performed for a case of deep convection over Oklahoma. If present at high enough concentrations, as might occur in proximity to land sources, INA bacteria are found to influence significantly: – (1) the average numbers and sizes of crystals in the clouds; (2) the horizontal cloud coverage in the free troposphere; and (3) precipitation and incident solar insolation at the surface, which influence rates of bacterial growth. At lower concentrations, the corresponding responses of cloud fields appear much lower or are ambiguous. In nature, the growth rates of INA bacteria on leaves prior to emission into the atmosphere are known to be highly dependent on temperature, precipitation and plant species. Consequently, the open question emerges of whether emissions of such ice-nucleating biogenic particles can then be modified by their own effects on clouds and atmospheric conditions, forming a weak feedback in climate or microclimate systems