Vibrational spectroscopy of adsorbed hydrogenous species studied by inelastic incoherent neutron scattering

Inelastic incoherent neutron scattering (INS) spectra of hydrogen strongly chemisorbed at coverages of greater than one monolayer on Pd black (Drijfhout, Amsterdam) were obtained (77K) without interference from adsorbed or type-C adsorbed hydrogen. The spectra were assigned by comparison with the vibrational spectra of transition-metal hydridocarbonyl compounds and indicated the occupation by H of two-fold bridging and terminal sites, the relative population of the terminal sites increasing at higher hydrogen coverage. INS spectra (ca 20 to 850 cm(^-1); 10, 16 and 77K) of c-C(_3)H(_6) adsorbed in Co(_4)Na(_4)Al(_12)Si(_12)O(_48), and of c-C(_3)H(_6) and c-C(_3)D(_6) in Mn(_3.5)Na(_5)Al(_12)Si(_12)O(_48) zeolite were consistent with C(_3v) symmetry of the M(II)-cyclopropane sorption complexes (M=Co or Mn). INS spectra (320 to 2230 cm(^-1); 77K) of Kadox 25 ZnO and H(_2) adsorbed on ZnO were obtained. The ѵ(_s) and ѵ(_δ) modes of type I Zn-H surface species were observed at 829 and 1708 cm(^-1). Recent assignments in the literature of the ѵ(_δ) mode of type I O-H species and the ѵ(_as) mode of type II Zn-H-Zn species to weak IR bands at 850 and 1475 cm(^-1) respectively were not corroborated by the INS results. The INS spectrum of ZnO contained an intense feature at 1346 cm(^-1) which was unchanged on adsorption, and assigned to bulk impurities. Raman and IR data of ZnO were also discussed. INS spectra (ca 20 to 850 cm(^-1); 10 and 77K) of C(_2)H(_2) and C(_2)D(_2) adsorbed in partially Ni(^++) ion-exchanged zeolite-Y indicated that the admolecules were non-linear (C(_2v) symmetry) and laterally bonded to the surface.. Bands centred at 774, 684, 546 and 75 cm(^-1) in the INS spectra (ca 20 to 850 cm(^-1); 10 and 77K) of H(_2)O adsorbed in Ca(_6)Al(_12)Si(_12)O(_48) zeolite at coverages of one H(_2)O molecule per Ca"*"*" ion or less were assigned to the wagging, twisting and rocking modes and to the doubly degenerate hindered translations parallel to the surface, respectively of H2O adsorbed at Ca"*"^ sites.INS spectra (lOK) of adsorbed by Zn^ ^Na^ 0^12 5^^11 5^48 ^^^^^^ showed bands at 72 and 155 cm""'", assigned to the tunnelling transitions E^^Eg and E^-^B respectively between the sublevels of the ground torsicxial state of a rigid H2 rotor, coifined to a plane parallel to the adsorbed surface, in a six-fold potential well of barrier height 29±3 kJ mol""'"

Unequal load-sharing in a multi-stage axial-flux permanent magnet synchronous machine.

Axial- ux machines, by the nature of their topology, are suited for high torque, low speed applications. In an attempt to improve the power-to-mass ratio of such a machine, the feasibility of stacking several alternate stator and rotor sections onto a common shaft in a multi-stage con guration was investigated. A prototype 5kW double-stage machine was developed for comparison to other designs presented in the literature. Although the results appeared promising, whilst under evaluation, an unequal load-sharing anomaly was observed: even though both stages contributed to driving the load, one stage always dominated. Furthermore, the discrepancy appeared to be dependent on the direction of rotation. This research investigates and explains the cause of the unequal load-sharing and presents design considerations to aid the future development of multi-stage machines

INTERVAL (investigation of NICE technologies for enabling risk-variable-adjusted-length) dental recalls trial: a multicentre randomised controlled trial investigating the best dental recall interval for optimum, cost-effective maintenance of oral health in dentate adults attending dental primary care

Background Traditionally, patients at low risk and high risk of developing dental disease have been encouraged to attend dental recall appointments at regular intervals of six months between appointments. The lack of evidence for the effect that different recall intervals between dental check-ups have on patient outcomes, provider workload and healthcare costs is causing considerable uncertainty for the profession and patients, despite the publication of the NICE Guideline on dental recall. The need for primary research has been highlighted in the Health Technology Assessment Group’s systematic review of routine dental check-ups, which found little evidence to support or refute the practice of encouraging 6-monthly dental check-ups in adults. The more recent Cochrane review on recall interval concluded there was insufficient evidence to draw any conclusions regarding the potential beneficial or harmful effects of altering the recall interval between dental check-ups. There is therefore an urgent need to assess the relative effectiveness and cost-benefit of different dental recall intervals in a robust, sufficiently powered randomised control trial (RCT) in primary dental care. Methods This is a four year multi-centre, parallel-group, randomised controlled trial with blinded outcome assessment based in dental primary care in the UK. Practitioners will recruit 2372 dentate adult patients. Patient participants will be randomised to one of three groups: fixed-period six month recall, risk-based recall, or fixed-period twenty-four month recall. Outcome data will be assessed through clinical examination, patient questionnaires and NHS databases. The primary outcomes measure gingival inflammation/bleeding on probing and oral health-related quality of life. Discussion INTERVAL will provide evidence for the most clinically-effective and cost-beneficial recall interval for maintaining optimum oral health in dentate adults attending general dental practice