Fluoride-ion solvation in non-aqueous electrolyte solutions

Understanding the factors that influence ion-solvent properties for the fluoride ion in organic solvents is key to the development of useful liquid electrolytes for fluoride-ion batteries. Using both experimental and computational methods, we examined a range of chemical and electrochemical properties for a set of organic solvents in combination with dry N,N,N-trimethylneopentylammonium fluoride (Np₁F) salt. Results showed that solvent electronic structure strongly influences Np₁F dissolution, and the pK_a of solvent protons provides a good guide to potential F⁻ reactivity. We found a number of organic solvents capable of dissolving Np₁F while providing chemically-stable F⁻ in solution and characterized three of them in detail: propionitrile (PN), 2,6-difluoropyridine (2,6-DFP), and bis(2,2,2-trifluoroethyl) ether (BTFE). Arrhenius analysis for Np₁F/PN, Np₁F/DFP, and Np₁F/BTFE electrolytes suggests that DFP facilitates the highest F⁻ ion mobility of the three neat solvents. Electrolyte mixtures of BTFE and amide co-solvents exhibit higher ionic conductivity than the neat solvents. This improved ionic conductivity is attributed to the ability of BTFE:co-solvent mixtures to partition between Np₁⁺ and F⁻ ion-aggregates, promoting better ion dissociation

Fluoride-ion solvation in non-aqueous electrolyte solutions

Understanding the factors that influence ion-solvent properties for the fluoride ion in organic solvents is key to the development of useful liquid electrolytes for fluoride-ion batteries. Using both experimental and computational methods, we examined a range of chemical and electrochemical properties for a set of organic solvents in combination with dry N,N,N-trimethylneopentylammonium fluoride (Np₁F) salt. Results showed that solvent electronic structure strongly influences Np₁F dissolution, and the pK_a of solvent protons provides a good guide to potential F⁻ reactivity. We found a number of organic solvents capable of dissolving Np₁F while providing chemically-stable F⁻ in solution and characterized three of them in detail: propionitrile (PN), 2,6-difluoropyridine (2,6-DFP), and bis(2,2,2-trifluoroethyl) ether (BTFE). Arrhenius analysis for Np₁F/PN, Np₁F/DFP, and Np₁F/BTFE electrolytes suggests that DFP facilitates the highest F⁻ ion mobility of the three neat solvents. Electrolyte mixtures of BTFE and amide co-solvents exhibit higher ionic conductivity than the neat solvents. This improved ionic conductivity is attributed to the ability of BTFE:co-solvent mixtures to partition between Np₁⁺ and F⁻ ion-aggregates, promoting better ion dissociation

Crummer SunTrust Portfolio Recommendations: Crummer Investment Management [2018]

The Crummer SunTrust Portfolio’s Investment Policy Statement requires that the management team determine portfolio allocations based on a consensus estimate of the market’s behavior throughout the coming year. This team has conducted thorough economic research using a variety of respected sources, developed a comprehensive market analysis, and heard from a well-rounded selection of industry experts (including economists, portfolio managers, and financial advisors) to inform this year’s investment decision. The team analyzed and discussed a range of likely economic possibilities for the upcoming year to shape a consensus that would serve to inform portfolio decisions. The team also evaluated the potential upsides and downsides relative to each economic factor to guide appropriate responses regarding individual stock selections and portfolio design. Finally, the team’s investment strategy has been to select securities trading at a significant discount to market value. We believe this strategy will mitigate any market volatility while providing a larger total return

Fluoride-ion solvation in non-aqueous electrolyte solutions

Understanding the factors that influence ion-solvent properties for the fluoride ion in organic solvents is key to the development of useful liquid electrolytes for fluoride-ion batteries. Using both experimental and computational methods, we examined a range of chemical and electrochemical properties for a set of organic solvents in combination with dry N,N,N-trimethylneopentylammonium fluoride (Np₁F) salt. Results showed that solvent electronic structure strongly influences Np₁F dissolution, and the pK_a of solvent protons provides a good guide to potential F⁻ reactivity. We found a number of organic solvents capable of dissolving Np₁F while providing chemically-stable F⁻ in solution and characterized three of them in detail: propionitrile (PN), 2,6-difluoropyridine (2,6-DFP), and bis(2,2,2-trifluoroethyl) ether (BTFE). Arrhenius analysis for Np₁F/PN, Np₁F/DFP, and Np₁F/BTFE electrolytes suggests that DFP facilitates the highest F⁻ ion mobility of the three neat solvents. Electrolyte mixtures of BTFE and amide co-solvents exhibit higher ionic conductivity than the neat solvents. This improved ionic conductivity is attributed to the ability of BTFE:co-solvent mixtures to partition between Np₁⁺ and F⁻ ion-aggregates, promoting better ion dissociation

Examining the Auroral Ionosphere in Three Dimensions Using Reconstructed 2D Maps of Auroral Data to Drive the 3D GEMINI Model

We use the Geospace Environment Model of Ion-Neutral Interactions (GEMINI) to create three-dimensional, time-dependent simulations of auroral ionospheric parameters in the localized, several 100 km region surrounding auroral arcs observed during a winter 2017 sounding rocket campaign, resolving three-dimensional features of fine-scale (km) flow structures in the vicinity of an auroral arc. The three-dimensional calculations of GEMINI allow (with sufficient driving data) auroral current closure to be investigated without idealizing assumptions of sheet-like structures or height integrated ionospheres. Datamaps for two nearly sheet-like arcs are reconstructed from replications of the Isinglass sounding rocket campaign data, and combined with camera-based particle inversions into a set of driving inputs to run the 3D time-dependent model. Comparisons of model results to radar density profiles and to in situ magnetometry observations are presented. Slices of volumetric current, flow, and conductance structures from model outputs are used to interpret closure currents in an auroral arc region, and are compared to original in situ measurements for verification. The predominant source of return current region field aligned current closure for these slow time variation events is seen to be from the conductance gradients, including the Hall. The importance of the versus terms in the determination of the current structure provides a more complicated picture than a previous GEMINI study, which relied predominantly on the divergence of the electric field to determine current structure. Sensitivity of data-driven model results to details of replication and reconstruction processes are discussed, with improvements outlined for future work

Origins of the Greenland shark (Somniosus microcephalus): Impacts of ice-olation and introgression

Herein, we use genetic data from 277 sleeper sharks to perform coalescent-based modeling to test the hypothesis of early Quaternary emergence of the Greenland shark (Somniosus microcephalus) from ancestral sleeper sharks in the Canadian Arctic-Subarctic region. Our results show that morphologically cryptic somniosids S. microcephalus and Somniosus pacificus can be genetically distinguished using combined mitochondrial and nuclear DNA markers. Our data confirm the presence of genetically admixed individuals in the Canadian Arctic and sub-Arctic, and temperate Eastern Atlantic regions, suggesting introgressive hybridization upon secondary contact following the initial species divergence. Conservative substitution rates fitted to an Isolation with Migration (IM) model indicate a likely species divergence time of 2.34 Ma, using the mitochondrial sequence DNA, which in conjunction with the geographic distribution of admixtures and Pacific signatures likely indicates speciation associated with processes other than the closing of the Isthmus of Panama. This time span coincides with further planetary cooling in the early Quaternary period followed by the onset of oscillating glacial-interglacial cycles. We propose that the initial S. microcephalus–S. pacificus split, and subsequent hybridization events, were likely associated with the onset of Pleistocene glacial oscillations, whereby fluctuating sea levels constrained connectivity among Arctic oceanic basins, Arctic marginal seas, and the North Atlantic Ocean. Our data demonstrates support for the evolutionary consequences of oscillatory vicariance via transient oceanic isolation with subsequent secondary contact associated with fluctuating sea levels throughout the Quaternary period—which may serve as a model for the origins of Arctic marine fauna on a broad taxonomic scale

Ethical Considerations for the Clinical Oncologist in an Era of Oncology Drug Shortages

Shortages of injectable drugs affect many cancer patients and providers in the U.S. today. Scholars and policymakers have recently begun to devote increased attention to these issues, but only a few tangible resources exist to guide clinical oncologists in developing strategies for dealing with drug shortages on a recurring basis. This article discusses existing information from the scholarly literature, policy analyses, and other relevant sources and seeks to provide practical ethical guidance to the broad audience of oncology professionals who are increasingly confronted with such cases in their practice. We begin by providing a brief overview of the history, causes, and regulatory context of oncology drug shortages in the U.S., followed by a discussion of ethical frameworks that have been proposed in this setting. We conclude with practical recommendations for ethical professional behavior in these increasingly common and challenging situations

Structure and Barrier to Methyl Group Internal Rotation for (CF₃)₂CFCF₂OCH₃ and Its Isomer n-C₄F₉OCH₃ (HFE-7100)

The hydrofluoroether C 4F 9OCH 3 (methoxynonafluorobutane, HFE-7100) has been studied by chirped pulse Fourier transform microwave spectroscopy as vapor from the liquid participates in a supersonic expansion of argon. Two isomers are present, (CF 3) 2CFCF 2OCH 3 and n-C 4F 9OCH 3, and in each case the rotational spectra of only one, dominating, conformer has been assigned. Rotational constants, centrifugal distortion constants, and barriers to methyl group internal rotation for the observed species have been experimentally determined for the first time. We note that Rays asymmetry parameter for the (CF 3) 2CFCF 2OCH 3 isomer is 0.007 083(1), indicating almost perfect asymmetry. Also, electronic structure calculations show an extremely short C(frame)-O ether bond length of 1.337