5 resultados para Vitamin B Complex
em Brock University, Canada
Resumo:
Palladium and platinum complexes of pyridoxamine, pyridoxine and pyridoxal have been prepared. The structures of the complexes PtCI2PM.H20, trans-PdC12 (PN)2 and [PLH+ ]2[PtC16] 2- ,H20 have been determined by use of single crystal x-ray studies. The compounds PdC12PH, trans-PdC12 (PN) 2 , cis-PdCI2 (PN)2 and cis PdC12 (PL)2 were also studied by use of carbon-13 nmr spectroscopy. All the complexes have also been characterised by use of infrared spectral studies. In the complexes, PtCI2PM.H20 and PdC12PM, the ligand pyridoxamine is chela ted to the metal through the aminomethyl nitrogen and the phenolate oxygen atoms whereas in the complexes, trans-PdCI2 (PN)2' cis-PdCI2 (PN)2 and cis-PdC12 (PL)2 the vitamin B6 ligands are coordinated to the metal through the pyridine ring nitrogen. The compounds [PLH+ ]2[PtCI6] 2- .H20 and [PMH2] 2+ [PdCI4] 2- .H20have no direct metal-ligand bonding, In all the complexes, the metal maintains a square planar coordination except in [PLH +] 2[PtCI6] 2- ,H20 where the metal is octahedrally coordinated. PH pyridoxamine [PMH ] 2+ = diprotonated pyridoxamine 2 PN = pyridoxine PL pyridoxal PLH+ protonated pyridoxal
Resumo:
This thesis can be broken down into two sections. Section one is a study . of the ionization mechanisms and the ion source optimization for Fast Atom Bombardment (FAB) ionization. For this study, several specially designed probe tips were created and tested under various experimental conditions. The aIm of this section is to understand the operating characteristics of a FAB IOn source better. The second section involves the study of several Vitamin B6 Schiff Base complexes using both positive and negative ion FAB MS. This section is an exploration of the usefulness of FAB MS as a structure probe for the metalcoordination complexes of Vitamin B6.
Resumo:
Mackenzie Chown Complex in the background and the path running next to it.
Resumo:
This qualitative phenomenological investigation explored six female Master of Education students' critical understandings of their identity and role negotiations, and their perceptions of environmental conditions that facilitated or impeded their identity explorations and negotiations within the institution. The interweaving of Feminist and Women's Development theories enabled the data to be examined under different, yet complementary, lenses. The data collection strategies included: four to five in-depth semistructured interviews, three take-home activities (involving identity mapping, object and metaphor identification, and strategy development), and the compilation of extensive interview notes as well as researcher reflections. The combination of a constant comparative method and a voice-centered method were used in tandem to analyze the data. Together they uncovered five emergent themes: (a) intricate understandings of key terms; (b) life-long learning and transformative pathways; (c) gender issues; (d) challenges, tensions, and possibilities; as well as (e) personal, professional, and educational implications. The findings underscored the possibility for both a singular static identity and dynamic multifaceted identities to exist in tandem, and the emergence of natural or logical identity intersections, as well as disjointed or colliding identity intersections. Ultimately, it is the continuous negotiation of internal and external spheres that contributes to the complexity and multidimensionality of graduate students' identities.
Resumo:
The initial timing of face-specific effects in event-related potentials (ERPs) is a point of contention in face processing research. Although effects during the time of the N170 are robust in the literature, inconsistent effects during the time of the P100 challenge the interpretation of the N170 as being the initial face-specific ERP effect. The interpretation of the early P100 effects are often attributed to low-level differences between face stimuli and a host of other image categories. Research using sophisticated controls for low-level stimulus characteristics (Rousselet, Husk, Bennett, & Sekuler, 2008) report robust face effects starting at around 130 ms following stimulus onset. The present study examines the independent components (ICs) of the P100 and N170 complex in the context of a minimally controlled low-level stimulus set and a clear P100 effect for faces versus houses at the scalp. Results indicate that four ICs account for the ERPs to faces and houses in the first 200ms following stimulus onset. The IC that accounts for the majority of the scalp N170 (icNla) begins dissociating stimulus conditions at approximately 130 ms, closely replicating the scalp results of Rousselet et al. (2008). The scalp effects at the time of the P100 are accounted for by two constituent ICs (icP1a and icP1b). The IC that projects the greatest voltage at the scalp during the P100 (icP1a) shows a face-minus-house effect over the period of the P100 that is less robust than the N 170 effect of icN 1 a when measured as the average of single subject differential activation robustness. The second constituent process of the P100 (icP1b), although projecting a smaller voltage to the scalp than icP1a, shows a more robust effect for the face-minus-house contrast starting prior to 100 ms following stimulus onset. Further, the effect expressed by icP1 b takes the form of a larger negative projection to medial occipital sites for houses over faces partially canceling the larger projection of icP1a, thereby enhancing the face positivity at this time. These findings have three main implications for ERP research on face processing: First, the ICs that constitute the face-minus-house P100 effect are independent from the ICs that constitute the N170 effect. This suggests that the P100 effect and the N170 effect are anatomically independent. Second, the timing of the N170 effect can be recovered from scalp ERPs that have spatio-temporally overlapping effects possibly associated with low-level stimulus characteristics. This unmixing of the EEG signals may reduce the need for highly constrained stimulus sets, a characteristic that is not always desirable for a topic that is highly coupled to ecological validity. Third, by unmixing the constituent processes of the EEG signals new analysis strategies are made available. In particular the exploration of the relationship between cortical processes over the period of the P100 and N170 ERP complex (and beyond) may provide previously unaccessible answers to questions such as: Is the face effect a special relationship between low-level and high-level processes along the visual stream?