Grading And Assessments: Correlations Of Variables Affecting Teaching And Course Assessments

Faculty assessments are a hot topic in academia. Mostly considered an unproven statistic holding the professor hostage for a good grade, the benefits are still in discussion.  At course end, we expect students to have the ability to analyze what we think they should have learned.  In reality, most students do not have the maturity to realize correlation for what you put into your education is what you get out.  Consensus is that it does not happen the way we plan.  Adding to the assessment issue is the clear fact that today most universities are adjunct professor-driven. Given these facts, the authors have statistically studied teaching assessments and associated grade point averages (GPA) representing academic rigor at a major non-profit university over the past three years.  The authors’ hypothesis is that there is no correlation between the two statistics.  This paper reviews the literature, provides the study methodology, and presents the findings

Distance Dependence of Nonadiabaticity in the Branching Between C–Br and C–Cl Bond Fission Following 1[n(O),π∗(C=O)] Excitation in Bromopropionyl Chloride

These experiments on bromopropionyl chloride investigate a system in which the barrier to C-Br fission on the lowest 1A\u27\u27 potential energy surface is formed from a weakly avoided electronic configuration crossing, so that nonadiabatic recrossing of the barrier to C-Br fission dramatically reduces the branching to C-Br fission. The results, when compared with earlier branching ratio measurements on bromoacetyl chloride, show that the additional intervening CH2 spacer in bromopropionyl chloride reduces the splitting between the adiabatic potential energy surfaces at the barrier to C-Br fission, further suppressing C-Br fission by over an order of magnitude. The experiment measures the photofragment velocity and angular distributions from the 248 nm photodissociation of Br (CH2)2COCl, determining the branching ratio between the competing primary C-Br and C-Cl fission pathways and detecting a minor C-C bond fission pathway. While the primary C-Cl:C-Br fission branching ratio is 1:2, the distribution of relative kinetic energies impar-ted to the C-Br fission fragments show that essentially no C-Br fission results from promoting the molecule to the lowest 1A\u27\u27 potential energy surface via the 1[n(O),pi*(C-O)] transition; C-Br fission only results from an overlapping electronic transition. The results differ markedly from the predictions of statistical transition state theories which rely on the Born-Oppenheimer approximation. While such models predict that, given comparable preexponential factors, the reaction pathway with the lowest energetic barrier on the 1A\u27\u27 surface, C-Br fission, should dominate, the experimental measurements show C-Cl bond fission dominates by a ratio of C-Cl:C-Br=1.0: \u3c0.05 upon excitation of the 1[n(O),pi*(C=O)] transition. We compare this result to earlier work on bromoacetyl chloride, which evidences a less dramatic reduction in the C-Br fission pathway (C-Cl:C-Br = 1.0:0.4) upon excitation of the same transition. We discuss a model in which increasing the distance between the C-Br and C=O chromophores decreases the electronic configuration interaction matrix elements which mix and split the 1n(O)pi*(C=O) and np(Br)sigma*(C-Br) configurations at the barrier to C-Br bond fission in bromopropionyl chloride. The smaller splitting between the adiabats at the barrier to C-Br fission increases the probability of nonadiabatic recrossing of the barrier, nearly completely suppressing C-Br bond fission in bromopropionyl chloride. Preliminary ah initio calculations of the adiabatic barrier heights and the electronic configuration interaction matrix elements which split the adiabats at the barrier to C-Br and C-Cl fission in both bromopropionyl chloride and bromoacetyl chloride support the interpretation of the experimental results. We end by identifying a class of reactions, those allowed by overall electronic symmetry but Woodward-Hoffmann forbidden, in which nonadiabatic recrossing of the reaction barrier should markedly reduce the rate constant, both for ground state and excited state surfaces

Competing C–Br and C–C Bond Fission Following 1[n(O),π∗(C=O)] Excitation in Bromoacetone: Conformation Dependence of Nonadiabaticity at a Conical Intersection

These experiments investigate the competition between C-C and C-Br bond fission in bromoacetone excited in the (1)[n(O),pi(*)(C=O)] absorption, elucidating the role of molecular conformation in influencing the probability of adiabatically traversing the conical intersection along the C-C fission reaction coordinate. In the first part of the paper, measurement of the photofragment velocity and angular distributions with a crossed laser-molecular beam time-of-flight technique identifies the primary photofragmentation channels at 308 nm. The time-of-flight spectra evidence two dissociation channels, C-Br fission and fission of one of the two C-C bonds, BrH2C-COCH3. The distribution of relative kinetic energies imparted to the C-Br fission and C-C fission fragments show dissociation is not occurring via internal conversion to the ground electronic state and allow us to identify these channels in the closely related systems of bromoacetyl- and bromopropionyl chloride. In the second part of the work we focus on the marked conformation dependence to the branching between C-C fission and C-Br fission. Photofragment angular distribution measurements show that C-Br fission occurs primarily from the minor, anti, conformer, giving a beta of 0.8, so C-C fission must dominate the competition in the gauche conformer. Noting that the dynamics of these two bond fission pathways are expected to be strongly influenced by nonadiabatic recrossing of the reaction barriers, we investigate the possible mechanisms for the conformation dependence of the nonadiabatic recrossing with low-level ab initio electronic structure calculations on the C-Br reaction coordinate and qualitative consideration of the conical intersection along the C-C reaction coordinate. The resulting model proposes that C-C bond fission,cannot compete with C-Br fission in the anti conformer because the dissociation samples regions of the phase space near the conical intersection along the CC fission reaction coordinate, where nonadiabaticity inhibits C-C fission, while from the gauche conformer C-C fission can proceed more adiabatically and dominate C-Br fission. A final experiment confirms that the branching ratio changes with the relative conformer populations in accord with this model

Self‐consistent molecular orbital methods. XXIII. A polarization‐type basis set for second‐row elements

The 6‐31G* and 6‐31G** basis sets previously introduced for first‐row atoms have been extended through the second‐row of the periodic table. Equilibrium geometries for one‐heavy‐atom hydrides calculated for the two‐basis sets and using Hartree–Fock wave functions are in good agreement both with each other and with the experimental data. HF/6‐31G* structures, obtained for two‐heavy‐atom hydrides and for a variety of hypervalent second‐row molecules, are also in excellent accord with experimental equilibrium geometries. No large deviations between calculated and experimental single bond lengths have been noted, in contrast to previous work on analogous first‐row compounds, where limiting Hartree–Fock distances were in error by up to a tenth of an angstrom. Equilibrium geometries calculated at the HF/6‐31G level are consistently in better agreement with the experimental data than are those previously obtained using the simple split‐valance 3‐21G basis set for both normal‐ and hypervalent compounds. Normal‐mode vibrational frequencies derived from 6‐31G* level calculations are consistently larger than the corresponding experimental values, typically by 10%–15%; they are of much more uniform quality than those obtained from the 3‐21G basis set. Hydrogenation energies calculated for normal‐ and hypervalent compounds are in moderate accord with experimental data, although in some instances large errors appear. Calculated energies relating to the stabilities of single and multiple bonds are in much better accord with the experimental energy differences

Self‐consistent molecular orbital methods. XXIII. A polarization‐type basis set for second‐row elements

The 6‐31G* and 6‐31G** basis sets previously introduced for first‐row atoms have been extended through the second‐row of the periodic table. Equilibrium geometries for one‐heavy‐atom hydrides calculated for the two‐basis sets and using Hartree–Fock wave functions are in good agreement both with each other and with the experimental data. HF/6‐31G* structures, obtained for two‐heavy‐atom hydrides and for a variety of hypervalent second‐row molecules, are also in excellent accord with experimental equilibrium geometries. No large deviations between calculated and experimental single bond lengths have been noted, in contrast to previous work on analogous first‐row compounds, where limiting Hartree–Fock distances were in error by up to a tenth of an angstrom. Equilibrium geometries calculated at the HF/6‐31G level are consistently in better agreement with the experimental data than are those previously obtained using the simple split‐valance 3‐21G basis set for both normal‐ and hypervalent compounds. Normal‐mode vibrational frequencies derived from 6‐31G* level calculations are consistently larger than the corresponding experimental values, typically by 10%–15%; they are of much more uniform quality than those obtained from the 3‐21G basis set. Hydrogenation energies calculated for normal‐ and hypervalent compounds are in moderate accord with experimental data, although in some instances large errors appear. Calculated energies relating to the stabilities of single and multiple bonds are in much better accord with the experimental energy differences

The Effective Fragment Molecular Orbital Method for Fragments Connected by Covalent Bonds

We extend the effective fragment molecular orbital method (EFMO) into treating fragments connected by covalent bonds. The accuracy of EFMO is compared to FMO and conventional ab initio electronic structure methods for polypeptides including proteins. Errors in energy for RHF and MP2 are within 2 kcal/mol for neutral polypeptides and 6 kcal/mol for charged polypeptides similar to FMO but obtained two to five times faster. For proteins, the errors are also within a few kcal/mol of the FMO results. We developed both the RHF and MP2 gradient for EFMO. Compared to ab initio, the EFMO optimized structures had an RMSD of 0.40 and 0.44 {\AA} for RHF and MP2, respectively.Comment: Revised manuscrip

Solution and Solid-State Characterization of Zn(II) Complexes Containing A New Tridentate N\u3csub\u3e2\u3c/sub\u3es Ligand

A new N2S ligand bis(pyridyl)(2-mercapto-1-methylimidazolyl)methane (2, Py2MeImS) has been synthesized and characterized. Treatment of this ligand with bromide and triflate salts of Zn(II) results in the complexes (Py2MeImS)ZnBr2 (3) and [(Py2MeImS)2Zn](OTf)2 (4), respectively. The solid-state structure of (Py2MeImS)ZnBr2 shows bidentate N,N-coordination of Py2MeImS to the zinc ion, with the sulfur atom of the 2-mercaptoimidazole moiety uncoordinated. Two conformers of 3 rapidly interconvert in solution at room temperature, and variable temperature NMR studies and DFT calculations were used to help assign the likely identity of these conformers. In contrast, the crystal structure of [(Py2MeImS)2Zn] (OTf)2 exhibits a zinc ion with a distorted octahedral geometry where the two sulfur atoms of the two ligands are coordinated to the zinc center in a cis-configuration. Even though the cis-isomer (4-cis) is calculated to be lower in energy than the trans-isomer (4-trans), the low temperature 1H NMR spectrum of 4 reveals a single symmetric species that is inconsistent with the cis-isomer observed in the solid-state structure. DFT calculations propose alternative higher energy structures, including a trans-configuration of the coordinated S-atoms of the two Py2MeImS ligands, as well as structures in which the 2-mercaptoimidazole groups are no longer coordinated to the zinc(II) center. These studies provide valuable insight into the potential binding modes of this new ligand and its behavior in solution