1,133 research outputs found

    Phenyl radical + propene: a prototypical reaction surface for aromatic-catalyzed 1,2-hydrogen-migration and subsequent resonance-stabilized radical formation

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    The C[subscript 9]H[subscript 11] potential energy surface (PES) was experimentally and theoretically explored because it is a relatively simple, prototypical alkylaromatic radical system. Although the C[subscript 9]H[subscript 11] PES has already been extensively studied both experimentally (under single-collision and thermal conditions) and theoretically, new insights were made in this work by taking a new experimental approach: flash photolysis combined with time-resolved molecular beam mass spectrometry (MBMS) and visible laser absorbance. The C[subscript 9]H[subscript 11] PES was experimentally accessed by photolytic generation of the phenyl radical and subsequent reaction with excess propene (C[subscript 6]H[subscript 5] + C[subscript 3]H[subscript 6]). The overall kinetics of C[subscript 6]H[subscript 5] + C[subscript 3]H[subscript 6] was measured using laser absorbance with high time-resolution from 300 to 700 K and was found to be in agreement with earlier measurements over a lower temperature range. Five major product channels of C[subscript 6]H[subscript 5] + C[subscript 3]H[subscript 6] were observed with MBMS at 600 and 700 K, four of which were expected: hydrogen (H)-abstraction (measured by the stable benzene, C[subscript 6]H[subscript 6], product), methyl radical (CH[subscript 3])-loss (styrene detected), H-loss (phenylpropene isomers detected) and radical adduct stabilization. The fifth, unexpected product observed was the benzyl radical, which was rationalized by the inclusion of a previously unreported pathway on the C[subscript 9]H[subscript 11] PES: aromatic-catalysed 1,2-H-migration and subsequent resonance stabilized radical (RSR, benzyl radical in this case) formation. The current theoretical understanding of the C[subscript 9]H[subscript 11] PES was supported (including the aromatic-catalyzed pathway) by quantitative comparisons between modelled and experimental MBMS results. At 700 K, the branching to styrene + CH[subscript 3] was 2-4 times greater than that of any other product channel, while benzyl radical + C[subscript 2]H[subscript 4] from the aromatic-catalyzed pathway accounted for ∌10% of the branching. Single-collision conditions were also simulated on the updated PES to explain why previous crossed molecular beam experiments did not see evidence of the aromatic-catalyzed pathway. This experimentally validated knowledge of the C[subscript 9]H[subscript 11] PES was added to the database of the open-source Reaction Mechanism Generator (RMG), which was then used to generalize the findings on the C[subscript 9]H[subscript 11] PES to a slightly more complicated alkylaromatic system.Think Global Education Trus

    Anxiety and depression following cumulative low-level exposure to organophosphate pesticides

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    Previous research suggests that individuals with a prior history of pesticide poisoning are at increased risk of psychiatric disorder (Freire and Koifman, 2013), but findings regarding the impact of cumulative low-level exposure are inconsistent. The aim of the current study was to investigate whether sheep farmers with a history of low-level exposure to organophosphate pesticides (1) report a higher level of psychological distress on subjective symptom questionnaires, compared to unexposed controls (2) also meet internationally agreed diagnostic criteria for a psychiatric disorder more often than unexposed controls. 127 sheep farmers were evaluated and compared to 78 unexposed controls, matched in terms of gender, education, level of intelligence, working status and area of residence. Both self-report measures and structured clinical interviews were used to assess mental health. The exposed cohort reported significantly higher rates of anxiety and depression when self-report questionnaires were used to evaluate mood, even when stressful life events, demographic and physical health factors were taken into account. However, when diagnostic interviews were used to assess mood, this pattern only held true for anxiety

    In vitro potency, in vitro and in vivo efficacy of liposomal alendronate in combination with γΎ T cell immunotherapy in mice

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    Nitrogen-containing bisphosphonate (N-BP), including zoledronic acid (ZOL) and alendronate (ALD), have been proposed as sensitisers in γΎ T cell immunotherapy in pre-clinical and clinical studies. Therapeutic efficacy of N-BPs is hampered by their rapid renal excretion and high affinity for bone. Liposomal formulations of N-BP have been proposed to improve accumulation in solid tumours. Liposomal alendronate (L-ALD) has been suggested as a suitable alternative to liposomal ZOL (L-ZOL), due to unexpected mice death experienced in pre-clinical studies with the latter. Only one study so far has proven the therapeutic efficacy of L-ALD, in combination with γΎ T cell immunotherapy, after intraperitoneal administration of γΎ T cell resulting in delayed growth of ovarian cancer in mice. This study aims to assess the in vitro efficacy of L-ALD, in combination with γΎ T cell immunotherapy, in a range of cancerous cell lines, using L-ZOL as a comparator. The therapeutic efficacy was tested in a pseudo-metastatic lung mouse model, following intravenous injection of γΎ T cell, L-ALD or the combination. In vivo biocompatibility and organ biodistribution studies of L-BPs were undertaken simultaneously. Higher concentrations of L-ALD (40–60 ÎŒM) than L-ZOL (3–10 ÎŒM) were required to produce a comparative reduction in cell viability in vitro, when used in combination with γΎ T cells. Significant inhibition of tumour growth was observed after treatment with both L-ALD and γΎ T cells in pseudo-metastatic lung melanoma tumour-bearing mice after tail vein injection of both treatments, suggesting that therapeutically relevant concentrations of L-ALD and γΎ T cell could be achieved in the tumour sites, resulting in significant delay in tumour growth

    The impact of residents' informedness and involvement on their perceptions of tourism impacts: The case of Bled

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    The tourism development debate includes many studies on how residents perceive positive or negative tourism impacts, based on sustainability, as understood by a three-pillar concept. However, so far studies were very limited in addressing certain requirements for sustainable tourism, such as informed stakeholders’ participation and cooperation – which represent the subject of this study. The survey that was undertaken follows previous ones in using the established three-pillar sustainability concept in order to define impacts of tourism. Further, it adds to tourism research by surveying informedness and developmental involvement. A four-dimensional informedness–involvement tourism grid is used to segment residents and their perceptions on tourism impacts in each segment are analysed. The model is empirically applied to the Slovenian lake and mountain destination of Bled. The findings confirm that highly informed and highly involved residents had better perceptions of tourism than all other groups, whereas those residents who were lowly informed and lowly involved had more negative perceptions of tourism. The survey contributes by expanding knowledge on resident perceptions of tourism by adding in the aspects of informedness and involvement. The proposed model can be applied to any destination to help manage residents’ opinions and consequently their support for tourism development

    Implementing sustainable tourism: a multi-stakeholder involvement management framework

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    Within the extensive body of literature on sustainable tourism (ST), its successful implementation is an emerging and important theme. The lack of or ineffective stakeholder participation is a major obstacle to ST realisation and there is little clarity as to how best to resolve this problem. This paper presents the findings of a purposive UK-based case study that evaluated stakeholder involvement in the implementation of ST. Using over fifty stakeholders’ accounts drawn from eight primary stakeholder groups, a ‘multi-stakeholder involvement management’ (MSIM) framework was developed. The MSIM framework consists of three strategic levels: attraction, integration and management of stakeholder involvement. Six stages are embedded within the three levels: scene-setting, recognition of stakeholder involvement capacity, stakeholder relationship management, pursuit of achievable objectives, influencing implementation capacity and monitoring stakeholder involvement. These are supported by the overarching notion of ‘hand-holding’ and key actions [e.g. managing stakeholder adaptability] that enhance stakeholder involvement in ST. Key words: Implementation, Sustainable Tourism, Stakeholder Involvement, Stakeholder framewor

    Comparison between Bipolar Hemiarthroplasty and Total Hip Arthroplasty for Unstable Intertrochanteric Fractures in Elderly Osteoporotic Patients

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    The present study was conducted to compare bipolar hemiarthroplasty (BA) with total hip arthroplasty (THA) in treatment of unstable intertrochanteric fractures in elderly osteoporotic patients. The THA group included 14 males and 26 females with a mean age of 73.4 years, and the BA group included 27 males and 45 females with a mean age of 76.5 years. Significant difference existed between the two groups in operation time, blood loss, transfusion volume and cost of hospitalization, while no remarkable difference was identified in hospitalization period, general complications, joint function, pain, rate of revision and mortality. No dislocation was observed in BA group while 3 occurred in THA group. The results indicated that for unstable intertrochanteric fractures in elderly osteoporotic patients, BA seems to be a better or more reasonable choice compared with THA for the reason of less blood loss, shorter operation time, lower cost and no dislocation
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