UPS studies of the adsorption and decomposition of methanol and formaldehyde on a tungsten(100) surface

In a study of the interaction of methanol and formaldehyde with an atomically clean W(100) surface at 300 K, ultra-violet photoelectron spectroscopy (U has been used to identify chemisorbed species and to investigate the nature of the chemical ical bonding in adsorbed layers of mixed composition. Tempe programmed thermal desorption has been used to assist in the interpretation of the data. Methanol and formaldehyde, when exposed to a clean W(100) surf decompose to give initially a mixture of adsorbed CO and H. After further exposure, increasing CO coverage causes loss of H. This is followed by the ad of molecular species producing photoelectron spectra and desorption products which are dependent on the coverage of pre-adsorbed CO. The nature of the molecular species, in relation to gas phase methanol and formaldehyde, is discussed.     

Dispersion of surface polaritons in uniaxial CdS

The dispersion of ordinary and extraordinary surface polaritons in uniaxial CdS has been measured using the ATR technique. The results have been compared with theoretical dispersion curves based on a classical oscillator model. The dielectric dispersion has also been generated. Comparison is made between the bulk phonons derived from Raman, infrared and from the surface mode data. Infrared measurements of small crystallites of CdS are in good agreement with the frequencies predicted for surface modes of small isolated spheres.     

Efficient synthesis of azide-bearing cofactor mimics

8-Azido-5'-aziridino-5'-deoxyadenosine (6), a novel cofactor mimic, was synthesized in nine steps from commercially available 2',3'-isopropylideneadenosine in approximately 4% overall yield. Crucial to this success was a very unorthodox phthalimide cleavage procedure, C8 azidation prior to aziridination and late stage alkylation of the 5' amino group with iodoethanol necessitated by the high degree of lability endowed by the aryl azide moiety. Aziridine 6 is envisioned as a useful biochemical tool by which to probe DNA and protein methylation patterns.     

Protonic modulation of redox properties in ionisable [2 x 2] grid-like metalloarrays

The oxidation state of the cobalt centres can be controlled by modification of the protonation state in [2 x 2] grid-like arrays based on ionisable bis(hydrazone) ligands, allowing conversion of the paramagnetic Co(II)(4) into the diamagnetic Co(III)(4) grid.     

Sextuplet phenyl embrace in a metal-organic Kagomé lattice

A novel Kagomé lattice that demonstrates the modular nature of metal-organic networks has been prepared and is to our knowledge the first example of a metal-organic coordination polymer that incorporates the sextuplet phenyl embrace as a supramolecular synthon.     

Anion control of the formation of geometric isomers in a triple helical array

The amide-substituted unsymmetrical ligand L(1) upon coordination to Co(2+) forms the dinuclear triple helicate [Co(2)(L(1))(3)](4+) which exists as both possible C(1) and C(3) symmetric geometric isomers in solution, however, upon addition of nitrate ions, the formation of an anion binding cavity is favoured and hence the sole product is the C(3) symmetric isomer in which all three amide substituents are hydrogen bonded to the nitrate anion.     

Homomorphic Feller Cocycles on a C*-Algebra

When a Fock-adapted Feller cocycle on a C*-algebra is regular,completely positive and contractive, it possesses a stochasticgenerator that is necessarily completely bounded. Necessaryand sufficient conditions are given, in the form of a sequenceof identities, for a completely bounded map to generate a weaklymultiplicative cocycle. These are derived from a product formulafor iterated quantum stochastic integrals. Under two alternativeassumptions, one of which covers all previously considered cases,the first identity in the sequence is shown to imply the rest.     

The acoustic bases for gender identification from children's voices.

The purpose of this study was to examine the acoustic characteristics of children's speech and voices that account for listeners' ability to identify gender. In Experiment I, vocal recordings and gross physical measurements of 4-, 8-, 12-, and 16-year olds were taken (10 girls and 10 boys per age group). The speech sample consisted of seven nondiphthongal vowels of American English (/ae/ "had," /E/ "head," /i/ "heed," /I/ "hid," /a/ "hod," /inverted v/ "hud," and /u/ "who'd") produced in the carrier phrase, "Say /hVd/ again." Fundamental frequency (f0) and formant frequencies (F1, F2, F3) were measured from these syllables. In Experiment II, 20 adults rated the syllables produced by the children in Experiment I based on a six-point gender rating scale. The results from these experiments indicate (1) vowel formant frequencies differentiate gender for children as young as four years of age, while formant frequencies and f0 differentiate gender after 12 years of age, (2) the relationship between gross measures of physical size and vocal characteristics is apparent for at least 12- and 16-year olds, and (3) listeners can identify gender from the speech and voice of children as young as four years of age, and with respect to young children, listeners appear to base their gender ratings on vowel formant frequencies. The findings are discussed in relation to the development of gender identity and its perceptual representation in speech and voice.