The effect of voice lessons on the clinical and perceptual skills of graduate students in speech-language pathology

Two groups of 10 speech-language pathology graduate students were each given 7 weeks of singing lessons to determine whether voice lessons could have an effect on their clinical and perceptual skills. Pre-, mid-, and posttests to measure various skills were designed and implemented. With use of paired sample statistical testing, statistically significant results were obtained. In addition, the subjective responses of the students show that the lessons were effective in improving pitch perception, breath control, and legato production or easy onset. This study supports efforts to integrate curricula in vocal performance and speech-language pathology.     

An inhibitor of the human UDP-GlcNAc 4-epimerase identified from a uridine-based library: a strategy to inhibit O-linked glycosylation

The biological study of O-linked glycosylation is particularly problematic, as chemical tools to control this modification are lacking. An inhibitor of the UDP-GlcNAc 4-epimerase that synthesizes UDP-GalNAc, the donor initiating O-linked glycosylation, would be a powerful reagent for reversibly inhibiting O-linked glycosylation. We synthesized a 1338 member library of uridine analogs directed to the epimerase by virtue of substrate mimicry. Screening of the library identified an inhibitor with a K(i) value of 11 microM. Tests against related enzymes confirmed the compound's specificity for the UDP-GlcNAc 4-epimerase. Inhibitors of a key step of O-linked glycan biosynthesis can be discovered from a directed library screen. Progeny thereof may be powerful tools for controlling O-linked glycosylation in cells.     

Photoelectron spectroscopy of S1 toluene: II. Intramolecular dynamics of selected vibrational levels in S1 toluene studied by nanosecond and picosecond time-resolved photoelectron spectroscopies

We present results which suggest that the photophysics of S(1) toluene is significantly more complicated than that of the related molecules p-fluorotoluene or p-difluorobenzene. We have measured a range of photoelectron spectra for a number of S(1) internal energies, on different time scales and at different temperatures, in an attempt to unravel the competing processes, but the final conclusion remains outstanding.     

Spectroscopy of Ethylenedione and Ethynediolide: A Reinvestigation

In an effort to characterize the electronic states of ethylenedione, OCCO, photoelectron‐photofragment coincidence (PPC) spectroscopy was applied to measure anions at m/z 56 and 57 using a pulsed discharge of glyoxal vapor and N₂O. PPC measurements at a photon energy of 3.20 eV yield photoelectron spectra in coincidence with either neutral photofragments or stable neutral products. The measurements showed that primarily stable neutral products were formed, with photoelectron spectra consistent with the oxyallyl diradical, C₃H₄O, and acetone enolate radical, C₃H₅O. The spectra were also found to have features nearly identical to those reported for OCCO and HOCCO by Sanov and co‐workers. The stability of the neutral products, as well as an examination of spectra reported for the oxyallyl anion and acetone enolate show that the previous assignments of OCCO and HOCCO are in error, and are instead attributed here to the oxyallyl diradical, C₃H₄O, and the acetone enolate radical, C₃H₅O.     

Nuclear quadrupole hyperfine structure in the microwave spectrum of HCl-N2O: electric field gradient perturbation of N2O by HCl

The microwave spectra of six isotopomers of HCl-N(2)O have been obtained in the 7-19 GHz region with a pulsed molecular beam, Fourier transform microwave spectrometer. The nuclear quadrupole hyperfine structure due to all quadrupolar nuclei is resolved and the spectra are analyzed using the Watson S-reduced Hamiltonian with the inclusion of nuclear quadrupole coupling interactions. The spectroscopic constants determined include rotational constants, quartic and sextic centrifugal distortion constants, and nuclear quadrupole coupling constants for each quadrupolar nucleus. Due to correlations of the structural parameters, the effective structure of the complex cannot be obtained by fitting to the spectroscopic constants of the six isotopomers. Instead, the parameters for each isotopomer are calculated from the A and C rotational constants and the chlorine nuclear quadrupole coupling constant along the a-axis, chi(aa). There are two possible structures; the one in which hydrogen of HCl interacts with the more electronegative oxygen of N(2)O is taken to represent the complex. The two subunits are approximately slipped parallel. For H (35)Cl-(14)N(2)O, the distance between the central nitrogen and chlorine is 3.5153 A and the N(2)O and HCl subunits form angles of 72.30 degrees and 119.44 degrees with this N-Cl axis, respectively. The chlorine and oxygen atoms occupy the opposite, obtuse vertices of the quadrilateral formed by O, central N, Cl, and H. Nuclear quadrupole coupling constants show that while the electric field gradient of the HCl subunit remains essentially unchanged upon complexation, there is electronic rearrangement about the two nitrogen nuclei in N(2)O.     

Interaction-induced dipoles of hydrogen molecules colliding with helium atoms: a new ab initio dipole surface for high-temperature applications

We report new ab initio results for the interaction-induced dipole moments Δμ of hydrogen molecules colliding with helium atoms. These results are needed in order to calculate collision-induced absorption spectra at high temperatures; applications include modeling the radiative profiles of very cool white dwarf stars, with temperatures from 3500 K to 9000 K. We have evaluated the dipoles based on finite-field calculations, with coupled cluster methods in MOLPRO 2006 and aug-cc-pV5Z (spdfg) basis sets for both the H and He centers. We have obtained values of Δμ for eight H(2) bond lengths ranging from 0.942 a.u. to 2.801 a.u., for 15 intermolecular separations R ranging from 2.0 a.u. to 10.0 a.u., and for 19 different relative orientations. In general, our values agree well with earlier ab initio results, for the geometrical configurations that are treated in common, but we have determined more points on the collision-induced dipole surface by an order of magnitude. These results make it possible to calculate transition probabilities for molecules in excited vibrational states, overtones, and rotational transitions with ΔJ > 4. We have cast our results in the symmetry-adapted form needed for absorption line shape calculations, by expressing Δμ as a series in the spherical harmonics of the orientation angles of the intermolecular vector and of a unit vector along the H(2) bond axis. The expansion coefficients depend on the H(2) bond length and the intermolecular distance R. For large separations R, we show that the ab initio values of the leading coefficients converge to the predictions from perturbation theory, including both classical multipole polarization and dispersion effects.     

N,N′‐Di­thio­bisphthal­imide–nitro­benzene (2/1): a Pn solvate with localized solvent mol­ecules ordered head‐to‐tail in channels

N,N′‐Di­thio­bisphthal­imide crystallizes from nitro­benzene solution as a solvate, 2C₁₆H₈N₂O₄S₂·C₆H₅NO₂, having space group Pn. The bisphthal­imide mol­ecules are linked by C—H?O hydrogen bonds and by aromatic π–π‐stacking interactions, forming a framework enclosing continuous channels running along the [100] direction and accounting for ca 20% of the unit‐cell volume. The nitro­benzene mol­ecules lie in these channels, ordered in a head‐to‐tail fashion and linked to the bis­phthal­imide framework by C—H?O and C—H?π(arene) hydrogen bonds.