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

Expression and Function of Serotonin 2A and 2B Receptors in the Mammalian Respiratory Network

Neurons of the respiratory network in the lower brainstem express a variety of serotonin receptors (5-HTRs) that act primarily through adenylyl cyclase. However, there is one receptor family including 5-HT2A, 5-HT2B, and 5-HT2C receptors that are directed towards protein kinase C (PKC). In contrast to 5-HT2ARs, expression and function of 5-HT2BRs within the respiratory network are still unclear. 5-HT2BR utilizes a Gq-mediated signaling cascade involving calcium and leading to activation of phospholipase C and IP3/DAG pathways. Based on previous studies, this signal pathway appears to mediate excitatory actions on respiration. In the present study, we analyzed receptor expression in pontine and medullary regions of the respiratory network both at the transcriptional and translational level using quantitative RT-PCR and self-made as well as commercially available antibodies, respectively. In addition we measured effects of selective agonists and antagonists for 5-HT2ARs and 5-HT2BRs given intra-arterially on phrenic nerve discharges in juvenile rats using the perfused brainstem preparation. The drugs caused significant changes in discharge activity. Co-administration of both agonists revealed a dominance of the 5-HT2BR. Given the nature of the signaling pathways, we investigated whether intracellular calcium may explain effects observed in the respiratory network. Taken together, the results of this study suggest a significant role of both receptors in respiratory network modulation

Study of the binary system fly ash/sugarcane bagasse ash (FA/SCBA) in SiO2/K2O alkali-activated binders

Due environmental problems related to Portland cement consumption, many studies have been performed to diminish its use. One solution is the development of alkali-activated binders, which can decrease CO2 emissions and energy consumption by 70% when compared to Portland cement production. In addition, an alkali-activated binder presents mechanical properties similar to Portland cement mixtures, which turns into an interesting material in civil construction. Aluminosilicate-based materials are important raw materials to produce the alkali-activated binders. Therefore, two residues are presented as an aluminosilicate source in this study: fly ash (FA) and sugarcane bagasse ash (SCBA). Both residues were obtained from a combustion process to generate energy, the former from coal and the latter from the bagasse of the sugarcane industry. In addition, the alkaline activating solution is an important factor to achieve improved mechanical properties. In this context, this study investigated the influence of four different SiO2/K2O molar ratios (0, 0.36, 0.75 and 1.22) in the activating solution with a constant water content, and three FA/SCBA binder proportions (75/25, 50/50 and 25/75). Microstructural characterization was carried out by X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, mercury intrusion porosimetry, pH and electrical conductivity measurements to study the evolution of the reaction process. The compressive strength of mortars was assessed in order to determine the optimum SiO2/K2O molar ratio and FA/SCBA ratio. The tests showed that a SiO2/K2O molar ratio of 0.75 and FA/SCBA proportion of 75/25 provided the best mechanical properties.The authors would like to thank the Ministerio de Educacion, Cultura y Deporte of Spain (Cooperacion Interuniversitaria program with Brazil, Project PHB-2011-0016-PC), CAPES Brazil (Project CAPES/DGU No. 266/12) and CNPq (process no 401724/2013-1).Castaldelli, V.; Moraes, J.; Akasaki, JL.; Pinheiro Melges, JL.; Monzó Balbuena, JM.; Borrachero Rosado, MV.; Soriano Martínez, L.... (2016). Study of the binary system fly ash/sugarcane bagasse ash (FA/SCBA) in SiO2/K2O alkali-activated binders. Fuel. 174:307-316. https://doi.org/10.1016/j.fuel.2016.02.020S30731617

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′