The solid-liquid interfacial free energy of close-packed metals: hard spheres and the Turnbull coefficient

Largely due to its role in nucleation and crystal-growth, the free energy of the crystal-melt interfacial free energy is an object of considerable interest across a number of scientific disciplines, especially in the materials-, colloid- and atmospheric sciences. Over fifty years ago, Turnbull observed that the interfacial free energies (scaled by the mean interfacial area per particle) of a variety of metallic elements exhibit a linear correlation with the enthalpy of fusion. This correlation provides an important empirical "rule-of-thumb" for estimating interfacial free energies, but lacks a compelling physical explanation. In this work we show that the interfacial free energies for close-packed metals are linearly correlated with the melting temperature, and are therefore primarily entropic in origin. We also show that the slope of this linear relationship can be determined with quantitative accuracy using a hard-sphere model, and that the correlation with the enthalpy of fusion reported by Turnbull follows as a consequence of the fact that the entropy of fusion for close-packed metals is relatively constant.Comment: 3 pages, 1 figure, to appear in J. Chem. Phy

Current status of the international Halley Watch infrared net archive

The primary purposes of the Halley Watch have been to promote Halley observations, coordinate and standardize the observing where useful, and to archive the results in a database readily accessible to cometary scientists. The intention of IHW is to store the observations themselves, along with any information necessary to allow users to understand and use the data, but to exclude interpretations of these data. Each of the archives produced by the IHW will appear in two versions: a printed archive and a digital archive on CD-ROMs. The archive is expected to have a very long lifetime. The IHW has already produced an archive for P/Crommelin. This consists of one printed volume and two 1600 bpi tapes. The Halley archive will contain at least twenty gigabytes of information

Compressibility of rotating black holes

Interpreting the cosmological constant as a pressure, whose thermodynamically conjugate variable is a volume, modifies the first law of black hole thermodynamics. Properties of the resulting thermodynamic volume are investigated: the compressibility and the speed of sound of the black hole are derived in the case of non-positive cosmological constant. The adiabatic compressibility vanishes for a non-rotating black hole and is maximal in the extremal case --- comparable with, but still less than, that of a cold neutron star. A speed of sound $v_s$ is associated with the adiabatic compressibility, which is is equal to $c$ for a non-rotating black hole and decreases as the angular momentum is increased. An extremal black hole has $v_s^2=0.9 \,c^2$ when the cosmological constant vanishes, and more generally $v_s$ is bounded below by $c/ {\sqrt 2}$.Comment: 8 pages, 1 figure, uses revtex4, references added in v

Synthesis and Characterization of Coated Gold Nanoparticles with Embedded SERS Tags

Gold nanoparticles were prepared with the potential to operate as drug delivery vehicles. Surface-enhanced Raman spectroscopy (SERS) is of particular importance as an optical bioimaging technique due to its ability to allow deep and high-resolution volumetric imaging of biological tissues. Characterization of the gold nanoparticles with para-mercaptobenzoic acid (pMBA), a SERS active molecule, silver, and a phospholipid bilayer was done using Raman and UV-vis spectroscopy and particle size analysis. Our results indicate successful coating of the gold nanoparticles and show consistent pMBA Raman spectroscopy peaks that will allow for the nanoparticle use in-vivo to be monitored

Brief of Brian Wolfman, Aderson B. Francois, and Eric Schnapper as Amici Curiae in Support of Petitioner in Peterson v. Linear Controls Incorporated, No. 18-1401 (U.S. Supreme Court June 6, 2019)

In Title VII disparate-treatment, employment-discrimination cases, the term “adverse employment action” originally developed as judicial shorthand for the statute’s text, which broadly prohibits any discriminatory conduct by an employer against an employee based on the employee\u27s race, color, religion, sex, or national origin. See 42 U.S.C. 2000e-2(a)(1). But what started simply as shorthand has taken on a life of its own and now improperly limits the statute’s reach. The Fifth Circuit’s version of the adverse-employment-action rule stands out as especially improper: Only an “ultimate employment decision”—a refusal to hire, a firing, a demotion, or the like—constitutes impermissible discrimination.In this amicus brief, we urge the Supreme Court to grant review and overturn the Fifth Circuit\u27s standard. We argue, first, that the Fifth Circuit\u27s ultimate-employment-decision standard is inconsistent with Title VII’s text and the Supreme Court’s Title VII decisions. Next, we show that the Fifth Circuit’s rule excludes many discriminatory employment practices that are unlawful in its sister circuits. The stories of discrimination victims from these other jurisdictions demonstrate that the Fifth Circuit’s approach is wrong. These individuals suffered discrimination that Title VII prohibits, but the Fifth Circuit’s standard would enable their employers to discriminate without consequence. Finally, we propose a standard consistent with Title VII’s text and Supreme Court precedent: As long as the employer’s intentional, discriminatory conduct imposes meaningful harm on the employee, it is prohibited by, and may be remedied under, Title VII