37,203 research outputs found
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 is associated with the adiabatic compressibility,
which is is equal to for a non-rotating black hole and decreases as the
angular momentum is increased. An extremal black hole has
when the cosmological constant vanishes, and more generally is bounded
below by .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 âadverse employment actionâ originally developed as judicial shorthand for the statuteâs 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 statuteâs reach. The Fifth Circuitâs version of the adverse-employment-action rule stands out as especially improper: Only an âultimate employment decisionââa refusal to hire, a firing, a demotion, or the likeâconstitutes 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 VIIâs text and the Supreme Courtâs Title VII decisions. Next, we show that the Fifth Circuitâs 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 Circuitâs approach is wrong. These individuals suffered discrimination that Title VII prohibits, but the Fifth Circuitâs standard would enable their employers to discriminate without consequence. Finally, we propose a standard consistent with Title VIIâs text and Supreme Court precedent: As long as the employerâs intentional, discriminatory conduct imposes meaningful harm on the employee, it is prohibited by, and may be remedied under, Title VII
- âŠ