Time filter

Source Type

Washington, PA, United States

Lombardi T.,Washington & Jefferson College
Leonardo | Year: 2014

This paper analyzes the co-occurrence network of saints in the corpus of images of St. Francis from 1230 to 1320 AD. The network of saints grows by preferential attachment reflecting the intercessory function of the artwork. The network, therefore, highlights important connections between intellectual and physical culture. © 2014 ISAST. Source

Dey B.,Carnegie Mellon University | McCracken M.E.,Carnegie Mellon University | McCracken M.E.,Washington & Jefferson College | Ireland D.G.,University of Glasgow | Meyer C.A.,Carnegie Mellon University
Physical Review C - Nuclear Physics | Year: 2011

The complete expression for the intensity in pseudo-scalar meson photoproduction with a polarized beam, target, and recoil baryon is derived using a density matrix approach that offers great economy of notation. A Cartesian basis with spins for all particles quantized along a single direction, the longitudinal beam direction, is used for consistency and clarity in interpretation. A single spin-quantization axis for all particles enables the amplitudes to be written in a manifestly covariant fashion with simple relations to those of the well-known Chew-Goldberger-Low-Nambu formalism. Possible sign discrepancies between theoretical amplitude-level expressions and experimentally measurable intensity profiles are dealt with carefully. Our motivation is to provide a coherent framework for coupled-channel partial-wave analysis of several meson photoproduction reactions, incorporating recently published and forthcoming polarization data from Jefferson Lab. © 2011 American Physical Society. Source

Sunderland D.P.,Washington & Jefferson College
Journal of Chemical Education | Year: 2014

A solid-state crystal structure laboratory exercise for undergraduates in either a general chemistry course or a more advanced inorganic chemistry course is described. Students explore the lattice arrangement of atoms in unit cells by building models supplied by the Institute for Chemical Education. Emphasis is placed on building three-dimensional visual models of various crystal systems to display close packing of atoms, to identify tetrahedral and octahedral holes, to reveal number of atoms per unit cell, and to highlight ion coordination numbers and size differences. The relationship between solid-state bonding and a material's physical properties is emphasized for elemental carbon. © 2014 The American Chemical Society and Division of Chemical Education, Inc. Source

Hoop C.L.,Washington & Jefferson College | Iuliucci R.J.,Washington & Jefferson College
Solid State Nuclear Magnetic Resonance | Year: 2013

The 13C chemical-shift anisotropy in anthracene derivatives (9,10-dimethylanthracene, 9,10-dihydroanthracene, dianthracene, and triptycene) has been measured by the 2D FIREMAT timed pulse sequence and the corresponding set of principal values has been determined by the TIGER processing method. These molecules expand the data base of 13C CSA measurements of fused aromatic rings some bridged by sp3 carbon resulting in an unusual bonding configuration, which leads to distinctive aromatic 13C CSA values. Crystal lattice distortions to the CSA were observed to change the isotropic shift by 2.5 to 3.3 ppm and changes as large as 8.3 ppm in principal components. Modeling of the CSA data by GIPAW DFT (GGA-PBE/ultrafine) shielding calculations resulted in an rms chemical-shift distance of 2.8 ppm after lattice including geometry optimization of the diffraction structures by the GIPAW method at GGA-PBE/ultrafine level. Attention is given to the substituted aromatic carbon in the phenyl groups (here forth referred to as the α-carbon) with respect to CSA modeling with electronic methods. The 13C CSA of this position is accurately determined due to its spectral isolation of the isotropic shift that limits overlap in the FIREMAT spectrum. In cases where the bridging ring is sp3 carbon, the current density is reduced from extending beyond the peripheral phenyl groups; this plays a significant role in the magnetic shielding of the α-position. Nuclear independent chemical-shift calculations based on GIAO DFT (B3LYP/6-31G(d)) shielding calculations were used to model the intramolecular π-interactions in dianthracene and triptycene. These NICS results estimate the isotropic shift of the α-position in dianthracene to be insignificantly affected by the presence of the neighboring aromatic rings. However, a notable change in isotropic shielding, Δσiso=-2.1 ppm, is predicted for the α- position of triptycene. Experimentally, the δ22 principal component at the α-position for both dianthracene and triptycene increases by at least 12 ppm compared to 9,10-dihydroanthracene. To rationalize this change, shielding calculations in idealized structures are explored. The spatial position of the bicyclic scaffolding of the bridging ring plays a key role in the large increase in δ22 for the α-carbon. © 2013 Elsevier Inc. All rights reserved. Source

Logan J.L.,Washington & Jefferson College | Rumbaugh C.E.,Washington & Jefferson College
Journal of Chemical Education | Year: 2012

"The Chemistry of Perfume" is a lab-only course for nonscience majors. Students learn fundamental concepts of chemistry through the context of fragrance, a pervasive aspect of daily life. The course consists of laboratories pertaining to five units: introduction, extraction, synthesis, characterization, and application. The introduction unit acquaints students with basic perfume terminology and the idea that chemical structure relates to scent. The extraction unit focuses on capturing and isolating fragrant essences from natural materials, whereas the synthetic unit considers mimicking such scents through chemical reactions. In the characterization unit, students analyze the components of perfume and fragrant materials. The course ends with the application unit in which students incorporate their fragrances into consumer products and toiletries. Curriculum structure, content, and student feedback are described. This perfume lab course results from an effort to increase interest in chemistry among nonscience students and encourage interdisciplinary learning. © 2012 American Chemical Society and Division of Chemical Education, Inc. Source

Discover hidden collaborations