A Pilot Survey of Vocal Health in Young Singers

The objective of this study was to determine the incidence of vocal problems in young choir singers and to correlate vocal problems with demographic and behavioral information. A questionnaire addressing vocal habits and hygiene was offered to 571 young choir singers, up to 25 years of age, who sing at least weekly; 129 (22.6%) responded. More than one-half of the respondents had experienced vocal difficulty, particularly older adolescents. Detrimental behaviors and circumstances surveyed were not reflective of the incidence of vocal difficulty, except for morning hoarseness, chronic fatigue, insomnia, and female gender after puberty. Voice care professionals should be aware that self-reported voice difficulties are common among young choral singers, especially postpubescent girls, and children with symptoms consistent with reflux (morning hoarseness) and emotional stress (insomnia). Laryngologists should communicate with choral conductors and singing teachers to enhance early identification and treatment of children with voice complaints, and to develop choral educational strategies that help decrease their incidence.     

Synthesis of tetrahydropyrido[2,3-b]pyrazine scaffolds from 2,3,5,6-tetrafluoropyridine derivatives

Reactions between N,N′-dimethylethylene diamine and a range of 2,3,5,6-tetrafluoropyridine derivatives provided ready access to the corresponding tetrahydropyrido[2,3-b]pyrazine systems if the substituent located at the 4-position of the pyridine ring was either hydrogen or an electron withdrawing substituent. In contrast, the presence of electron donating substituents at the 4-position made the formation of ring-fused products much more difficult. The two-step sequential nucleophilic substitution procedures from pentafluoropyridine gave convenient and adaptable methodology for the synthesis of polyfunctional tetrahydropyrido[2,3-b]pyrazine scaffolds of interest to the life science discovery arenas.     

Substitution reactions of [Ru(dppe)(CO)(H(2)O)(3)][OTf](2)

The labile nature of the coordinated water ligands in the organometallic aqua complex [Ru(dppe)(CO)(H(2)O)(3)][OTf](2) (1) (dppe = Ph(2)PCH(2)CH(2)PPh(2); OTf = OSO(2)CF(3)) has been investigated through substitution reactions with a range of incoming ligands. Dissolution of 1 in acetonitrile or dimethyl sulfoxide results in the facile displacement of all three waters to give [Ru(dppe)(CO)(CH(3)CN)(3)][OTf](2) (2) and [Ru(dppe)(CO)(DMSO)(3)][OTf](2) (3), respectively. Similarly, 1 reacts with Me(3)CNC to afford [Ru(dppe)(CO)(CNCMe(3))(3)][OTf](2) (4). Addition of 1 equiv of 2,2'-bipyridyl (bpy) or 4,4'-dimethyl-2,2'-bipyridyl (Me(2)bpy) to acetone/water solutions of 1 initially yields [Ru(dppe)(CO)(H(2)O)(bpy)][OTf](2) (5a) and [Ru(dppe)(CO)(H(2)O)(Me(2)bpy)][OTf](2) (6a), in which the coordinated water lies trans to CO. Compounds 5a and 6a rapidly rearrange to isomeric species (5b, 6b) in which the ligated water is trans to dppe. Further reactivity has been demonstrated for 6b, which, upon dissolution in CDCl(3), loses water and coordinates a triflate anion to afford [Ru(dppe)(CO)(OTf)(Me(2)bpy)][OTf] (7). Reaction of 1 with CH(3)CH(2)CH(2)SH gives the dinuclear bridging thiolate complex [[(dppe)Ru(CO)](2)(mu-SCH(2)CH(2)CH(3))(3)][OTf] (8). The reaction of 1 with CO in acetone/water is slow and yields the cationic hydride complex [Ru(dppe)(CO)(3)H][OTf] (9) via a water gas shift reaction. Moreover, the same mechanism can also be used to account for the previously reported synthesis of 1 upon reaction of Ru(dppe)(CO)(2)(OTf)(2) with water (Organometallics 1999, 18, 4068).     

Characterization of the Reaction of Chloroacetaldehyde with Single and Double Stranded DNA

Chloroacetaldehyde reacts with viral M13mp18 single and double stranded DNA to form the highly fluorescent adducts, etheno-AMP and etheno-CMP.

Absorbance and fluorescence spectroscopy can be used to monitor and characterize these reactions. Both single and double stranded DNA showed increases in the absorbance following reaction with the aldehyde. The fluorescence also increased in these two groups and continued to rise with increasing time of incubation until a point of saturation was reached. The fluorescence of the double stranded moiety was considerably enhanced following reaction with the aldehyde while that of the single stranded population was not, making this method appropriate for the separation of small quantities of the two populations of DNA.     

Application of the single comparator method to instrumental photon activation analysis

Journal of Radioanalytical and Nuclear Chemistry - Instrumental photon activation analysis (IPAA) is nondestructive and multi-elemental analysis method like instrumental neutron activation...     

Twist-Bend Nematic Glasses: The Synthesis and Characterisation of Pyrene-based Nonsymmetric Dimers

A selection of pyrene-based liquid crystal dimers have been prepared, containing either methylene-ether or diether linked spacers of varying length and parity. All the diether linked materials, CBOnO.Py (n=5, 6, 11, 12), exhibit conventional nematic and smectic A phases, with the exception of CBO11O.Py which is exclusively nematic. The methylene-ether linked dimer, CBnO.Py, with an even-membered spacer (n=5) was solely nematogenic, but odd-members (n=6, 8, 10) exhibited both nematic and twist-bend nematic phases. Replacement of the cyanobiphenyl fragment by cyanoterphenyl giving CT6O.Py, gave elevated melting and nematic-isotropic transition temperatures, and SmA and SmC_A phases were observed on cooling the nematic phase. Intermolecular face-to-face associations of the pyrene moieties drive glass formation, and all these materials have a glass transition temperature at or above room temperature. The stability of the glassy twist-bend nematic phase allowed for its study using AFM, and the helical pitch length, P_TB, was measured as 6.3 and 6.7 nm for CB6O.Py and CB8O.Py, respectively. These values are comparable to the shortest pitch of a twist-bend nematic phase measured to date.     

The effect of low levels of dopants upon the formation and properties of beta-phase molybdenum nitride

The addition of 1 wt% Pd, Au, Ni and Cu dopants has been demonstrated to strongly alter the morphology of beta-phase molybdenum nitride prepared by treatment of MoO₃ with a 3/1 H₂/N₂ mixture at 750 °C. Furthermore, the addition of Pd significantly enhances the surface area and the formation of the nitride phase. It is proposed that the facile formation of molybdenum bronzes in this system is important in this respect. The dopants have also been observed to modify the denitridation characteristics of the beta-phase, with an overall reduction of the proportion of NH₃ formed upon using a 3/1 H₂/Ar mixture with respect to the undoped sample.     

Treatment of trigeminal ganglion neurons in vitro with NGF,GDNF or BDNF: effects on neuronal survival,neurochemical properties and TRPV1-mediated neuropeptide secretion

Background  

Nerve growth factor (NGF), glial cell line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF) all play important roles in the development of the peripheral sensory nervous system. Additionally, these growth factors are proposed to modulate the properties of the sensory system in the adult under pathological conditions brought about by nerve injury or inflammation. We have examined the effects of NGF, GDNF and BDNF on adult rat trigeminal ganglion (TG) neurons in culture to gain a better understanding of how these growth factors alter the cytochemical and functional phenotype of these neurons, with special attention to properties associated with nociception.