Diluted bitumen (dilbit) is an unconventional oil produced by the oil sands industry in Canada. Despite the knowledge available on hydrocarbon toxicity, the effects of diluted bitumen on benthic ...organisms are still largely unknown. Moreover, in Quebec there are only provisional threshold values of 164 mg/kg C10–C50 for chronic effects and 832 mg/kg for acute effects. The protectiveness of these values for benthic invertebrates has not been tested for heavy unconventional oils such as dilbit. Two benthic organisms, the larvae of Chironomus riparius and Hyalella azteca, were exposed to these two concentrations and to an intermediate concentration (416 mg/kg) of two dilbits (DB1 and DB2) and a heavy conventional oil (CO). The aim of the study was to assess the sublethal and lethal effects of spiked sediment by dilbit. The oil was rapidly degraded in the sediment, especially in the presence of C. riparius. Amphipods were much more sensitive to oil than chironomids. LC50-14d values for H. azteca were 199 mg/kg C10–C50 for DB1, 299 mg/kg for DB2 and 8.42 mg/kg for CO compared to LC50-7d values for C. riparius of 492 mg/kg for DB1, 563 mg/kg for DB2 and 514 mg/kg for CO. The size of the organisms was reduced compared to controls for both species. The defense enzymes (GST, GPx, SOD and CAT) were not good biomarkers in these two organisms for this type of contamination. The current provisional sediment quality criteria seem too permissive for heavy oils and should be lowered.
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•Oil disappeared from the sediment faster in the presence of chironomids than amphipods.•Amphipods were more sensitive than chironomid larvae.•Amphipods were much more sensitive to conventional heavy oils than to dilbits.•Chironomid larvae were more sensitive to dilbits.•Antioxidant and detoxification enzymes and genotoxicity markers were not adapted to our toxicity tests.
Open stoping has become a popular mining method in hard rock mines, not only due to the safety of the method as a non-entry approach, but also because of the high extraction rate and low costs. At ...mine sites, stope performance is evaluated by calculating stope overbreak using the stability chart. However, limitations of the stability chart regarding the precision of the predictions, non-consideration of factors such as the influence of blasting, and the exclusion of underbreak have led to non-optimal designs. The capabilities of today's computers have increased the amount of data being collected and the power of models being built. This article presents a step towards a new stope design approach where stope overbreak and underbreak are measured and georeferenced using octrees at an approximately cubic metre resolution and predicted using multivariate statistical models (partial least square, linear discriminant analysis, and random forest). Results show that overbreak and underbreak location along the design surface and their magnitude are predicted with good precision using a random forest model. These predictions are used to build the expected geometry of the open stope. The resolution of the data and the use of multivariate analysis has enabled the prediction of variation in stope performance along the design surface, going well beyond the simple qualitative per stope face prediction provided by a traditional stability chart approach. Keywords: stope design, stope reconciliation, overbreak, underbreak, multivariate, prediction, random forest.
Context. A sample of mostly old metal-rich dwarf and turn-off stars with high eccentricity and low maximum height above the Galactic plane has been identified. From their kinematics, it was suggested ...that the inner disk is their most probable birthplace. Their chemical imprints may therefore reveal important information about the formation and evolution of the still poorly understood inner disk. Aims. To probe the formation history of these stellar populations, a detailed analysis of a sample of very metal-rich stars is carried out. We derive the metallicities, abundances of α elements, ages, and Galactic orbits. Methods. The analysis of 71 metal-rich stars is based on optical high-resolution échelle spectra obtained with the FEROS spectrograph at the ESO 1.52-m Telescope at La Silla, Chile. The metallicities and abundances of C, O, Mg, Si, Ca, and Ti were derived based on LTE detailed analysis, employing the MARCS model atmospheres. Results. We confirm the high metallicity of these stars reaching up to Fe i/H = 0.58, and the sample of metal-rich dwarfs can be kinematically subclassified in samples of thick disk, thin disk, and intermediate stellar populations. All sample stars show solar α-Fe ratios, and most of them are old and still quite metal rich. The orbits suggest that the thin disk, thick disk and intermediate populations were formed at Galactocentric distances of ~8 kpc, ~6 kpc, and ~7 kpc, respectively. The mean maximum height of the thick disk subsample of Zmax ~ 380 pc, is lower than for typical thick disk stars. A comparison of α-element abundances of the sample stars with bulge stars shows that the oxygen is compatible with a bulge or inner thick disk origin. Our results suggest that models of radial mixing and dynamical effects of the bar and bar/spiral arms might explain the presence of these old metal-rich dwarf stars in the solar neighbourhood.
Abstract As mining activities are expected to develop at greater depths, seismic responses to the blasting of development drift segments are expected to increase and present a greater hazard. A ...database of 379 development blasts was created for a mining site, recording seismic responses related to these blasts and rock mass structural and geologic properties associated with the drift segment. A random forest, multivariate statistical predictive model was developed with 75% of the drift segments. The model's performance was validated by analyzing 100 drift segments that were not used to create the model. The improved understanding of the variation in the intensity of seismic responses to development blasting through the sum of the seismic moment of the events is a clear benefit of random forest model development for the case study. In addition, the development of the predictive random forest model provides a tool for decision-makers to select performance criteria thresholds that they deem acceptable. The threshold selected would depend on the risk appetite of the decision-makers. The proposed approach provides quantitative data on the distribution of seismic hazards associated with development blasting which managers can rely on. Combining the proposed approach with current seismic protocols used at different mine sites could improve our management of seismic risk associated with development blasting. Using the predictive model for the sector and period studied has shown a potential to increase the accuracy, sensitivity, and precision for anticipating a high-intensity seismic response to a development blast.
Summary
The Resonant inelastic X‐ray scattering or resonant Raman scattering is an inelastic process of second order that becomes important when the energy of the excitation radiation is below but ...close to an absorption edge. In this process, the emitted photons have a continuous energy distribution with a high energy cut‐off limit. In the last few years, experiments of resonant Raman scattering has become a very powerful technique to investigate excitations of electrons in solids. A qualitative study of the calcium local structure in the different layers of teeth was carried out. In order to perform the analysis, several measurements of tooth samples were achieved using monochromatic synchrotron radiation at the XRF station of the D09B‐XRF beamline at the Brazilian synchrotron facility (LNLS, Campinas), below and close to the K absorption edge of Ca to inspect the resonant Raman scattering spectra. First of all, the spectra were analyzed with specific software to fit the experimental data. After that, the residuals were determined and a fast Fourier transform smoothing procedure was applied, taking into account the instrument functions of the detecting system. These oscillations present patterns that depend of the tooth layer, i.e. of the calcium state.
This paper uses a case study from Brunswick Mine in Canada to determine a representative elementary volume (REV) of a jointed rock mass in the vicinity of important underground infrastructure. The ...equivalent geometrical and mechanical property REV sizes were determined based on fracture systems modeling and numerical experiments on a synthetic rock mass. Structural data collected in massive sulphides were used to generate a large fracture system model (FSM), 40
m×40
m×40
m. This FSM was validated and subsequently sampled to procure 40 cubic specimens with a height to width ratio of 2 based on sample width from 0.05 to 10
m. The specimens were introduced into a 3D particle flow code (PFC3D) model to create synthetic rock mass (SRM) samples. The geometrical REV of the rock mass was determined based on the number of fractures in each sampled volume (P
30) and the volumetric fracture intensity (P
32) of the samples. The mechanical REV was estimated based on the uniaxial compressive strength (UCS) and elastic modulus (
E) of the synthetic rock mass samples.
The REV size of the rock mass was determined based on a series of statistical tests. The
T-test was used to assess whether the means of the samples were statistically different from each other and the
F-test to compare the calculated variance. Finally, the coefficient of variation, for the synthetic rock mass geometrical and mechanical properties, was plotted against sample size. For this particular site the estimated geometrical REV size of the rock mass was 3.5
m×3.5
m×7
m, while the mechanical property REV size was 7
m×7
m×14
m. Consequently, for engineering purposes the largest volume (7
m×7
m×14
m) can be considered as the REV size for this rock mass.
Context. Although several attempts have been made to identify solar-type members on the main sequence of the nearby open cluster Coma Berenices (Mel 111), the population of the lower main sequence is ...still poorly known. Aims. We observed 46 new candidates to search for new members and monitored known spectroscopic-binary members to determine orbital parameters. Methods. We obtained a total of 903 radial-velocity measurements of 69 solar-type stars in the field of Mel 111 with the CORAVEL spectrovelocimeter over 20 years. Results. Among the 35 stars from Trumpler's list, 23 are members according to their radial velocities and photometry. We were able to confirm the membership of only 8 stars among the 46 candidates observed. Six double-lined and ten single-lined spectroscopic binaries were discovered. Six only are members and an orbit was determined for them and for 4 double-lined non-members. The binary frequency is 22% (7/32). The cluster mean radial velocity is +0.01 ± 0.08 km s-1 based on 28 members. Conclusions. The lower main sequence of the Coma Berenices open cluster is still rather poorly populated. The cluster size may be much larger that usually accepted. Accordingly extensive programmes to determine precise proper motions, radial velocities and photometry should be undertaken to identify faint cluster members outside the cluster central area. If a significant population of faint members cannot be identified, Coma Ber could be a prominent example of dynamical evolution leading to star evaporation.
ING3 (Inhibitor of Growth 3) is a candidate tumor suppressor gene whose expression is lost in tumors. Aims: We want to identify and characterize new tumor suppresor functions for ING3. Methods: We ...conduct experiments in yeast and human cells depleted or not for ING3 and exposed to genotoxic agents. Results: - ING3-depleted human cells and yeast cells deleted for its ortholog YNG2 are sensitive to DNA damage suggesting a conserved role in response to such stress. - In human cells, ING3 is recruited to DNA double strand breaks and is required for ATM activation. - In response to doxorubicin, ATM activation is dependent on ING3 but not on TIP60, whose recruitment to DNA breaks also depends on ING3. - These events lead to ATM-mediated phosphorylation of NBS1 and of major mediators of the DNA damage response. - Upon genotoxic stress, DNA repair by Non Homologous End Joining (NHEJ) or Homologous Recombination (HR) were impaired in absence of ING3. - Immunoglobulin Class Switch Recombination (CSR), a physiological mechanism requiring NHEJ repair, was impaired in the absence of ING3. Conclusions: Since deregulation of DNA double strand break repair is associated with genomic instability, we propose a novel function of ING3 as a caretaker tumor suppressor involved in the DNA damage signaling and repair. Funding: A.M. was a recipient of a doctoral fellowship from La Ligue Contre le Cancer and Region Bretagne. R.P. & M.G. were recipients of from Ulysses “The France – Ireland Exchange Scheme”. N. Bigot was a recipient of ANR program (SAFE 2012) (ANR-11-RPIB-0012). C. References: Cell Death Differ. 2019 Feb 25. doi: 10.1038/s41418-019-0305-x. Epub ahead of print
In this paper we report a study of an important property of biomineralized phases, crystallinity, on the basis of previous results for synthetic apatite. Crystallinity is not only important for ...understanding biomineralization, it is also related to the maturation and mechanisms of growth of calcium phosphates in biological surroundings. We studied two kinds of sample, teeth as an example of biomineralized tissues and dental calculi (adhering) as an example of mineralization without participation of biological agents, except possibly bacteria. The investigation focused on study of ν ₁-ν ₃ infrared absorption bands of PO ₄ ³⁻ phosphates. We used ATR (attenuated total reflection) analysis to examine human dental tissues and tartar on several samples. The results confirm for the first time previous assumptions about the growth and maturation of dental calculi, i.e., crystallinity progresses from regions of high crystallinity to regions of lower crystallinity, and, in addition, its quantification with spatial resolution in the sample. A gradual pattern was observed in dental calculus. Another result from this study was that cementum and dentine had similar crystallinity, despite their different biological and mechanical functions.
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