Influence of the Alkali-promoted phase transformation in monazite for selective recovery of rare-oxides using deep eutectic solvents

This is the final version. Available on open access from Elsevier via the DOI in this recordThe physico-chemical changes occurring during the high-temperature phase transformation of monazite in the presence of Na2CO3 at 1000 °C for 2 h duration at monazite: Na2CO3 ratios between 1.0 and 5.0, were investigated. The formation of sodium lanthanide phosphates was prevalent above a monazite:alkali ratio of 2, however, below this ratio, the dephosphorization of monazite as Na3PO4 and solid solutions occur offering unique selectivity for rare-earth oxide separation from the mineral matrix. Cyclic voltammetry of pure CeO2, La2O3, Nd2O3, and PrO2/Pr2O3 was carried out in the deep eutectic solvent Ethaline (1:2 mixture of choline chloride and ethylene glycol) proving the electrochemical activity of these oxides. Electrodissolution of pure oxides and water-leached monazite after high-temperature reaction with a ratio of 1:1 was carried out in a 0.1 mol/L glucose solution in Ethaline showing a preferential solubility of 23.85% for pure Nd2O3. In contrast, pure oxides of CeO2, La2O3 and PrO2/Pr2O3 were found to be insoluble. We also observed that electrodissolution of the water leached monazite was not possible because of the inert behaviour of solid solutions. Avoiding cerium oxidation during the high-temperature process will lead to a method for further selectivity for rare-earth oxide processing using staged electro-chemical winning of oxides.Natural Environment Research Council (NERC)Ministry of Science, Innovation and University of Spai

Properties of the ultraviolet flux of type Ia supernovae: an analysis with synthetic spectra of SN 2001ep and SN 2001eh

The spectral properties of type Ia supernovae in the ultraviolet (UV) are investigated using the early-time spectra of SN 2001ep and SN 2001eh obtained using the Hubble Space Telescope (HST). A series of spectral models is computed with a Monte Carlo spectral synthesis code, and the dependence of the UV flux on the elemental abundances and the density gradient in the outer layers of the ejecta is tested. A large fraction of the UV flux is formed by reverse fluorescence scattering of photons from red to blue wavelengths. This process, combined with ionization shifts due to enhanced line blocking, can lead to a stronger UV flux as the iron-group abundance in the outer layers is increased, contrary to previous claims.Comment: 14 pages, 13 figures. Replaced with revised version accepted for publication in MNRA

Dark Energy and Gravity

I review the problem of dark energy focusing on the cosmological constant as the candidate and discuss its implications for the nature of gravity. Part 1 briefly overviews the currently popular `concordance cosmology' and summarises the evidence for dark energy. It also provides the observational and theoretical arguments in favour of the cosmological constant as the candidate and emphasises why no other approach really solves the conceptual problems usually attributed to the cosmological constant. Part 2 describes some of the approaches to understand the nature of the cosmological constant and attempts to extract the key ingredients which must be present in any viable solution. I argue that (i)the cosmological constant problem cannot be satisfactorily solved until gravitational action is made invariant under the shift of the matter lagrangian by a constant and (ii) this cannot happen if the metric is the dynamical variable. Hence the cosmological constant problem essentially has to do with our (mis)understanding of the nature of gravity. Part 3 discusses an alternative perspective on gravity in which the action is explicitly invariant under the above transformation. Extremizing this action leads to an equation determining the background geometry which gives Einstein's theory at the lowest order with Lanczos-Lovelock type corrections. (Condensed abstract).Comment: Invited Review for a special Gen.Rel.Grav. issue on Dark Energy, edited by G.F.R.Ellis, R.Maartens and H.Nicolai; revtex; 22 pages; 2 figure

The Redshift Completeness of Local Galaxy Catalogs

There is considerable interest in understanding the demographics of galaxies within the local universe (defined, for our purposes, as the volume within a radius of 200 Mpc or z ≤ 0.05). In this pilot paper, using supernovae (SNe) as signposts to galaxies, we investigate the redshift completeness of catalogs of nearby galaxies. In particular, type Ia SNe are bright and are good tracers of the bulk of the galaxy population, as they arise in both old and young stellar populations. Our input sample consists of SNe with redshift ≤0.05, discovered by the flux-limited ASAS-SN survey. We define the redshift completeness fraction (RCF) as the number of SN host galaxies with known redshift prior to SN discovery, determined, in this case, via the NASA Extragalactic Database, divided by the total number of newly discovered SNe. Using SNe Ia, we find $\mathrm{RCF}=78{\pm }_{7}^{6}$% (90% confidence interval) for z < 0.03. We examine the distribution of host galaxies with and without cataloged redshifts as a function of absolute magnitude and redshift, and, unsurprisingly, find that higher-z and fainter hosts are less likely to have a known redshift prior to the detection of the SN. However, surprisingly, some ${L}_{* }$ galaxies are also missing. We conclude with thoughts on the future improvement of RCF measurements that will be made possible from large SN samples resulting from ongoing and especially upcoming time-domain surveys

Cold storage of ‘Palmer’ mangoes sorted based on dry matter content using portable near infrared (VIS-NIR) spectrometer

The objective of this study was to use dry matter (DM) calibration models to sort ‘Palmer’ mangoes prior cold storage and to evaluate the physiological and chemical changes during the storage period. PLS model developed with fruit from 2015/2016 season was not adequate to predict DM content in fruit from 2016/2017 (not adjusted R2). Therefore, VIS‐NIR spectra from 2016/2017 season were incorporated into data set and a new model was developed (RMSEcv of 10.5 g.kg−1, urn:x-wiley:01458892:media:jfpp13644:jfpp13644-math-0001 of 0.75). With the new model, ‘Palmer’ mangoes were sorted into two maturity stages (150 g.kg−1 and 110 g.kg−1) which resulted in quality differences mainly in relation to DM and SSC. Portable VIS‐NIR spectrometer can be used to sort fruit according to maturity stages based on DM content and this classification affect fruit quality during cold storage as fruit with higher DM (150 g.kg−1) presented better quality than fruit with lower DM (110 g.kg−1)

Search for the standard model Higgs boson decaying to a bbˉb\bar{b} pair in events with no charged leptons and large missing transverse energy using the full CDF data set

We report on a search for the standard model Higgs boson produced in association with a vector boson in the full data set of proton-antiproton collisions at $\sqrt{s} = 1.96$ TeV recorded by the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.45 fb$^{-1}$. We consider events having no identified charged lepton, a transverse energy imbalance, and two or three jets, of which at least one is consistent with originating from the decay of a $b$ quark. We place 95% credibility level upper limits on the production cross section times standard model branching fraction for several mass hypotheses between 90 and $150 \mathrm{GeV}/c^2$. For a Higgs boson mass of $125 \mathrm{GeV}/c^2$, the observed (expected) limit is 6.7 (3.6) times the standard model prediction.Comment: Accepted by Phys. Rev. Let

Search for the standard model Higgs boson decaying to a bb pair in events with one charged lepton and large missing transverse energy using the full CDF data set

We present a search for the standard model Higgs boson produced in association with a W boson in sqrt(s) = 1.96 TeV p-pbar collision data collected with the CDF II detector at the Tevatron corresponding to an integrated luminosity of 9.45 fb-1. In events consistent with the decay of the Higgs boson to a bottom-quark pair and the W boson to an electron or muon and a neutrino, we set 95% credibility level upper limits on the WH production cross section times the H->bb branching ratio as a function of Higgs boson mass. At a Higgs boson mass of 125 GeV/c2 we observe (expect) a limit of 4.9 (2.8) times the standard model value.Comment: Submitted to Phys. Rev. Lett (v2 contains clarifications suggested by PRL

Search for the standard model Higgs boson decaying to a bb pair in events with two oppositely-charged leptons using the full CDF data set

We present a search for the standard model Higgs boson produced in association with a Z boson in data collected with the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.45/fb. In events consistent with the decay of the Higgs boson to a bottom-quark pair and the Z boson to electron or muon pairs, we set 95% credibility level upper limits on the ZH production cross section times the H -> bb branching ratio as a function of Higgs boson mass. At a Higgs boson mass of 125 GeV/c^2 we observe (expect) a limit of 7.1 (3.9) times the standard model value.Comment: To be submitted to Phys. Rev. Let

Observation of associated near-side and away-side long-range correlations in √sNN=5.02 TeV proton-lead collisions with the ATLAS detector

Two-particle correlations in relative azimuthal angle (Δϕ) and pseudorapidity (Δη) are measured in √sNN=5.02  TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1  μb-1 of data as a function of transverse momentum (pT) and the transverse energy (ΣETPb) summed over 3.1<η<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|Δη|<5) “near-side” (Δϕ∼0) correlation that grows rapidly with increasing ΣETPb. A long-range “away-side” (Δϕ∼π) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ΣETPb, is found to match the near-side correlation in magnitude, shape (in Δη and Δϕ) and ΣETPb dependence. The resultant Δϕ correlation is approximately symmetric about π/2, and is consistent with a dominant cos⁡2Δϕ modulation for all ΣETPb ranges and particle pT