Using molecular-dynamics simulation, we have calculated the interfacial free energy γ between a hard-sphere fluid and hard spherical and cylindrical colloidal particles, as functions of the particle radius R and the fluid packing fraction η = ρσ 3 /6, where ρ and σ are the number density and hard-sphere diameter, respectively. These results verify that Hadwiger's theorem from integral geometry, which predicts that γ for a fluid at a surface, with certain restrictions, should be a linear combination of the average mean and Gaussian surface curvatures, is valid within the precision of the calculation for spherical and cylindrical surfaces up to η ≈ 0.42. In addition, earlier results for γ for this system [Bryk et al., Phys. Rev. E 68, 031602 (2003)] using a geometrically based classical density functional theory are in excellent agreement with the current simulation results for packing fractions in the range where Hadwiger's theorem is valid. However, above η ≈ 0.42, γ (R) shows significant deviations from the Hadwiger form indicating limitations to its use for high-density hard-sphere fluids. Using the results of this study together with Hadwiger's theorem allows one, in principle, to determine γ for any sufficiently smooth surface immersed in a hard-sphere fluid. The solid-liquid interfacial free energy γ is a central property governing a wide variety of technologically important phenomena from crystal nucleation and growth to wetting. Because accurate and reliable experimental measurements of γ are rare, much effort has been devoted in recent years to the development of atomistic simulation methods to determine this quantity for interfaces between coexisting solid and fluid phases [1][2][3][4][5] and for systems in which the solid is modeled by a static wall [6][7][8][9][10][11]. These efforts have thus far been primarily restricted to planar interfaces; however, there are many physically relevant systems in which interfacial curvature is relevant, for example, in the formation of critical nuclei in nucleation [12][13][14] or the solvation or wetting of hydrophobic nanoscale particles [15][16][17]. There have been a number of previous simulation studies that examine the effect of curvature in liquid-vapor interfaces [18][19][20][21], but direct simulation studies on solid-liquid interfaces are lacking. In this Rapid Communication, we examine the dependence of γ on the surface curvature for a hard-sphere fluid in contact with curved hard surfaces, specifically at spherical and cylindrical colloidal particles.König et al. [22] have recently shown that Hadwiger's theorem [23] from integral geometry puts severe restrictions on the shape (curvature) dependence of the interfacial free energy. In their analysis, the interfacial free energy of an object with a surface S is given bywhere h and κ are constants depending upon the thermodynamic state, but independent of the specific surface S. HereH andK are the averaged mean and Gaussian curvatures of S, * Author to whom correspondence should be addressed: blaird@ku.edu d...

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Use of fentanyl test strips (FTS) to test illicit drugs has been shown to be an effective harm-reduction tool for raising awareness of fentanyl risks, increased self-efficacy to prevent overdose, and safer use behavior changes. From March to June 2020, a total of 6 Massachusetts municipal police departments piloted FTS kit distribution during post-overdose outreach visits, community outreach, and related programming. The Police Assisted Addiction and Recovery Initiative developed the kits, trained departments, and oversaw implementation. The pilot evaluation involved site observations, process measures, and interviews with staff and kit recipients. For every kit distributed, there was approximately 1 health or support service or referral provided; 320 kits were distributed. Key themes from interviews were conceptualizing FTS as a tool, collaborations, and adaptations. Police departments that partnered with community programs amplified project reach. FTS distribution is a simple yet powerful tool that community providers and police can offer alongside linkage to care services and engagement with people who use drugs and their family and friends.