Diffusion Independent, Bimolecular, Photoinduced Electron Transfer Reactions

A variety of expressions have been developed which relate the Gibbs energy of activation to the net Gibbs energy change of a reaction. One of these, the Marcus relation, was developed specifically for outersphere electron transfer reactions. It predicted that, as the reaction exergonicity increased, the activation energy would decrease to zero and then increase. Consequently, the reaction rate constant should increase to a maximum and then decrease in the so-called inverted region.;Extensive investigation over many years failed to find evidence for the inverted region. Recently, five types of experiments have yielded clear evidence of inverted behavior. In all five cases the reactions were unimolecular to pseudo-unimolecular.;This thesis describes the investigation of a series of photo-induced electron transfer reactions. The bimolecular quenching constants k{dollar}\sb{lcub}\rm q{rcub}{dollar} and the static quenching critical distances R{dollar}\sb{lcub}\rm c{rcub}{dollar} were found from transient and steady-state emission spectroscopies, using emission from the reactant electron donors. R{dollar}\sb{lcub}\rm c{rcub}{dollar} was also determined by EPR measurements on the product acceptor radicals.;The chemical systems comprised an electron acceptor, methyl viologen, a sacrificial electron donor for EPR experiments, EDTA, and a homologous series of photosensitive ruthenium electron donors. All ruthenium compounds except Ru (bpy) {dollar}\sb3{dollar}Cl{dollar}\sb2{dollar} were synthesized by literature methods and identified by optical absorption and fast atom bombardment mass spectroscopies. The reactants were dispersed in glycerol at room temperature.;The results show that k{dollar}\sb{lcub}\rm q{rcub}{dollar} remains at a diffusion controlled maximum as the reactions become more exergonic. R{dollar}\sb{lcub}\rm c{rcub}{dollar} increases to a maximum when {dollar}\Delta{dollar}G {dollar}\simeq{dollar} {dollar}-0.6{dollar} eV and then decreases. A similar curve is found for R{dollar}\sb{lcub}\rm c{rcub}{dollar} calculated from EPR data, proving that the reaction under investigation is indeed electron transfer, and that the parameter R{dollar}\sb{lcub}\rm c{rcub}{dollar} is real and independent of the species (reactant or product) used to identify it.;It is concluded that the Marcus relation applies to bimolecular charge-separation outer-sphere electron-transfer reactions and is observed in the absence of diffusion.;An initial project which examined electron transfer in the same systems at low temperature and was not completed is described briefly

Canada’s multiple voices diplomacy in climate change negotiations: a focus on Québec

Abstract: This article sheds light on the complexity of international climate change negotiations in a federal country, like Canada, where there is no clear attribution of full power over international negotiation concerning this issue. Climate change is a multi-level and multi-stakeholder issue, one that can only be tackled successfully if all actors, at all levels of government, are involved in the process. In recent years, Canadian provinces, especially Québec, have become intensely involved in climate change paradiplomacy. That situation has led to a Canadian paradox where the Government of Québec worked to respect the Kyoto Protocol and act accordingly, while Canada opted out of the Protocol in 2011

Survival, predation, and behaviour of the Mahoenui giant wētā ('Deinacrida mahoenui': Anostostomatidae: Orthoptera)

Introduced mammalian pests, such as rats (Rattus spp.), house mice (Mus musculus), brushtail possums (Trichosurus vulpecula), and European hedgehogs (Erinaceus europaeus), have been implicated in the suppression or extinction of many endemic invertebrate species in New Zealand, including the large-bodied giant wētā (Anostostomatidae: Deinacrida). The Mahoenui giant wētā (MGW; D. mahoenui) is the only lowland giant wētā species still naturally present on the mainland of New Zealand, where the last remaining individuals of the original population are currently restricted to an 187ha mainland reserve (Mahoenui Giant Wētā Scientific Reserve; MGWSR) in Mahoenui, western King Country. Having sought refuge in the introduced woody shrub, gorse (Ulex europaeus), these wētā have survived in the presence of introduced mammalian predators for almost six decades. However, due to natural succession, the reserve is gradually reverting to native bush and wētā monitoring data shows potential signs of population decline. Concerns for the species survival have been raised as it is unknown how wētā will cope in an altered habitat alongside mammalian predators. In chapter 2, we used 14-years’ of site-occupancy monitoring data to explore changes to the reserves’ gorse mosaic and MGW population. We additionally assessed the effect of abiotic covariates on MGW occupancy and detection probabilities in 2005 and 2018. Furthermore, we assessed mammalian pest population dynamics within the reserve over the past seven years. Significant changes to the reserve’s gorse mosaic were identified, whereby unbrowsed, tall bushes, which may provide less protection to wētā, are now dominant in 2018. Population trajectory analysis revealed the MGW population has decline since 2012. This result was consistent with naïve occupancy estimates and the increase in search time (0.3hrs/year) required to find wētā, suggesting the population is in a state of decline. Plot location was identified as an important covariate for predicting MGW occupancy in 2018, whereby plots in edge habitat, potentially being preferred or safer, had a higher occupancy probability. Mammalian pests (rats, house mice, brushtail possums, and European hedgehogs) appear to be present within the reserve year-round, populations peaking in summer and autumn. In chapter 3, we used radiotelemetry to explore MGW survival rates, movement patterns, and diurnal refuge use in gorse and native vegetation during summer (n=14), autumn (n=31), and spring (n=10). Survival rates, in relation to predation, revealed MGW inhabiting native vegetation were nine times more likely to be predated than those inhabiting gorse. This result suggests native species such as mahoe (Melicytus ramiflorus), and tree ferns (Dicksonia fibrosa and Cyathea spp.) do not provide good protection to MGW from mammalian predators. Assessment of movement behaviour revealed MGW move less in autumn (~3m/48hrs) compared to summer (~10m/48hrs) and spring (~8m/48hrs), and most commonly follow a movement pattern consistent with random-walk. Movement behaviour was also found to be temperature dependant, with both male and female MGW moving significantly further in warmer weather (>13.5°C). Radiotracked MGW were found to take refuge above 2.5m in the canopy of native vegetation, whereas in gorse habitat, wētā were most commonly found taking refuge between 0.62 – 2.38m in the denser foliage of unbrowsed gorse bushes. Furthermore, no radiotracked wētā were observed with another individual in autumn, compared to eight and 26 observations in summer and spring. In chapter 4, we attempted to identify potential mammalian predators of the MGW by analysing the stomach contents of ship rats (R. rattus; n=10), house mice (n=10), brushtail possums (n=5), and feral cats (Felis catus; n=2). Ship rats were identified as likely predators of MGW within the MGWSR. However, due to the limited number of stomachs and species analysed, further analysis is recommended. Collectively, these results provide an overview of the MGW reserve and population status, in addition to important ecological information that can be used to inform future management, monitoring, and translocation

Social service referrals in a general hospital : an evaluative survey of 23 out-patient clinics of the Vancouver General Hospital, 1960

The purpose of the present study has been to examine the referral system used by the doctors and others in making requests from Medical Social Services in Vancouver General Hospital. More specifically, the examination was confined to the present use by medical personnel of the referral form, (M 234). This pilot project has been undertaken to explore the referral system in relation to improvement of medical social services offered in the out-patient department. As background, the history of medical social work, standards of medical care, and a resume of Medical Social Service in the out-patient department of Vancouver General Hospital is reviewed. Basic information for the study was obtained through a survey of all requests made to medical social service from out-patient clinics during November, 1960. In addition to this, twenty-four doctors of the specialty clinics were canvassed through the medium of a questionnaire, and personal interviews, to ascertain their opinions on (a) most convenient methods of referral, (b) kinds of social information, (c) reasons for referral, (d) and suggestions for improving medical social services. The findings of the study indicate that slightly less than one-third of the new patients admitted to the out-patient department clinics for November, 1960, were referred for medical social services. There is evidence that a far higher percentage than this could benefit from such services. The Social Service Department has been aware of the possibilities for some time, and the present study was undertaken in order to gain facts, opinions, and clarification towards improving the referral system in the interests of more adequate standards of medical care.Arts, Faculty ofSocial Work, School ofGraduat