Stereodynamical studies of velocity aligned photofragments

The state resolved stereodynamics of bimolecular reactions can be probed using velocity aligned photofragments as reagents, and polarised, Doppler resolved laser detection techniques for the products. The new strategy and its application to the reaction O(1D) + N2O→ NO + NO are outlined

Localisation of NMU1R and NMU2R in human and rat central nervous system and effects of neuromedin-U following central administration in rats

Rationale: Neuromedin-U (NmU) is an agonist at NMU1R and NMU2R. The brain distribution of NmU and its receptors, in particular NMU2R, suggests widespread central roles for NmU. In agreement, centrally administered NmU affects feeding behaviour, energy expenditure and pituitary output. Further central nervous system (CNS) roles for NmU warrant investigation. Objectives: To investigate the CNS role of NmU by mapping NMU1R and NMU2R mRNA and measuring the behavioural, endocrine, neurochemical and c-fos response to intracerebroventricular (i.c.v.) NmU. Methods: Binding affinity and functional potency of rat NmU was determined at human NMU1R and NMU2R. Expression of NMU1R and NMU2R mRNA in rat and human tissue was determined using semi-quantitative reverse-transcription polymerase chain reaction. In in-vivo studies, NmU was administered i.c.v. to male Sprague-Dawley rats, and changes in grooming, motor activity and pre-pulse inhibition (PPI) were assessed. In further studies, plasma endocrine hormones, [DOPAC + HVA]/[dopamine] and [5-HIAA]/[5-HT] ratios and levels of Fos-like immunoreactivity (FLI) were measured 20 min post-NmU (i.c.v.). Results: NmU bound to NMU1R (KI, 0.11±0.02 nM) and NMU2R (KI, 0.21±0.05 nM) with equal affinity and was equally active at NMU1R (EC50, 1.25±0.05 nM) and NMU2R (EC50, 1.10±0.20 nM) in a functional assay. NMU2R mRNA expression was found at the highest levels in the CNS regions of both rat and human tissues. NMU1R mRNA expression was restricted to the periphery of both species with the exception of the rat amygdala. NmU caused a marked increase in grooming and motor activity but did not affect PPI. Further, NmU decreased plasma prolactin but did not affect levels of corticosterone, luteinising hormone or thyroid stimulating hormone. NmU elevated levels of 5-HT in the frontal cortex and hypothalamus, with decreased levels of its metabolites in the hippocampus and hypothalamus, but did not affect dopamine function. NmU markedly increased FLI in the nucleus accumbens, frontal cortex and central amygdala. Conclusions: These data provide further evidence for widespread roles for NmU and its receptors in the brain

THE STEREOCHEMISTRY OF THE O(1D)+N2O-]NO+NO REACTION VIA VELOCITY-ALIGNED PHOTOFRAGMENT DYNAMICS

Velocity-aligned, superthermal O(1D) atoms generated via the photodissociation of N2O have been employed to investigate the stereodynamics of the title reaction. The power of this experimental technique, when coupled with Doppler-resolved, polarized laser-induced fluorescence probing of the reaction products, is demonstrated by reference to the specific reaction channel leading to NO(v′=0)+NO(v′=16,17), which is shown to proceed via direct stripping dynamics. Furthermore, the observed product-state selective linear and angular momenta disposals imply that the reaction is stereodynamically constrained to occur via collinear collision geometries. © 1992 American Institute of Physics

STEREODYNAMICS OF PHOTON-INDUCED REACTIONS VIA DOPPLER-RESOLVED LASER-INDUCED FLUORESCENCE SPECTROSCOPY - PHOTODISSOCIATION OF HONO2 AND THE REACTION OF O((1)D) WITH CH4

The application of polarised, Doppler-resolved laser-induced fluorescence (LIF) probing of the products scattered from photon-induced 'half-collision' (photodissociation) and 'full-collision' (bimolecular reaction) processes is developed to include the velocity dependence of their stereodynamics. Fourier-transform inversion procedures are used to derive the products' speed distributions W(v′) and vector correlations βij(v′) (a) in the photodissociation of HONO2 and (b) in the bimolecular reaction of O(1D) with CH4. In the former example, they provide new insight into the stereodynamics of the photodissociation, HONO2 + hν → HO(v = 0, N) + NO2(X̃, Ã) In the latter, together with newly developed LAB → CM simulation methods, they provide new insight into the stereodynamics of the reaction, O(1D) + CH4 → OH(v = 4, N) + CH3 The OH is shown to be generated with its rotational angular momentum j′, constrained to lie in a plane directed perpendicular to its centre-of-mass relative velocity, k′

MEASUREMENTS OF VECTOR CORRELATIONS IN BIOMOLECULAR REACTIONS BY LASER-PUMP AND PROBE TECHNIQUES

Velocity-aligned, superthermal atoms generated via polarised molecular photodissociation have been used to investigate vector correlations of bimolecular reactions. Doppler-resolved, polarised laser-probe techniques can measure correlations between k (the reagents' relative-velocity vectors), k′ (the reaction products' velocity vectors) and J′ (the products' rotational angular momenta using a simple laboratory to centre-of-mass frame transformation. This approach to the study of the dynamical stereo-chemistry of chemical reactions is illustrated by two examples, O(1D)+N2O→NO+NO and O(3P)+CS→CO+S. © 1991

Use of Alkali-Activated Fly Ashes for Soil Treatment

The use of alkali-activated fly ashes (AAFA) to improve engineering properties of clayey soils is a novel solution, alternative to the widely diffused improvement based on the use of traditional binders such as lime and cement. An experimental investigation on chemo-physical evolution of alkali-activated binders and their use for soil improvement has been developed. Treated samples were prepared by mixing soil and fly ash with water and alkaline solution and dynamically compacted. Mechanical behaviour has been investigated by means of triaxial tests performed on treated samples compacted at optimum water content. Addition of alkali activated binder increased stiffness and shear strength of treated samples, whose extent depends on binder content and curing time