???????????? ?????? ???????????? ????????? ?????? ??? ?????? ?????????????????? ??????

Department of ChemistryThe environmental issues caused by the hydrocarbon energy sources have emerged as one of the most urgent challenges in 21st century. The development of clean and renewable energy technologies is critical to meet both the environment regulations and to circumvent dependence upon the fossil fuels. This situation has brought a new idea about the future society solely driven by hydrogen-based energy infrastructures, so-called hydrogen economy. The production and utilization of hydrogen via water electrolysis and fuel cells, respectively, are key ingredients to realize the hydrogen economy. However, the high cost of those devices hinders their wide adoption, which can be attributed primarily to the use of precious metal electrocatalysts such as Pt and Ir that are required for efficient operation. In this context, the development of active non-precious metal catalysts (NPMCs) is of great significance. In this dissertation, new NPMCs based on carbon nanotube (CNT) have been designed and prepared for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER), where the ORR is an important half-reaction that critically affects the fuel cell performance, while the OER & HER are involved in water electrolysis. CNT was selected as the carbon support owing to its high conductivity, chemical stability, and surface tunability, advantageous for electrocatalysis. In Chapter 2, we developed a facile and scalable synthetic method for carbon nanostructures comprising active heteroatom-doped carbon (HDC) layers coated on CNT (CNT/HDC), which was exploited as a metal-free ORR electrocatalyst. The preparation involves the adsorption of heteroatom-containing ionic liquid (IL) on the CNT walls via van der Waals and cationic-?? interactions and subsequent carbonization, yielding CNT/HDC core???sheath nanostructures. The design enables both the efficient utilization of surface active sites of HDC layers and high electric conductivity of the CNT core. The CNT/HDC catalyst exhibited high ORR activity and reaction kinetics comparable to a commercial Pt/C catalyst in alkaline media, and an excellent anion exchange membrane fuel cell (AEMFC) performance. The IL-derived CNT/HDC catalysts could be prepared using various types of IL precursors. Iron and nitrogen codoped carbon (Fe???N/C) catalysts have emerged as the most promising electrocatalysts for the ORR among various classes of NPMCs. A growing body of literature suggests that Fe???Nx species are major active sites in a Fe???N/C catalyst. Chapter 3 presents a general ???silica-protective-layer-assisted??? approach that can preferentially generate the catalytically active Fe???Nx sites in Fe???N/C catalysts while suppressing the formation of less-active large Fe-based particles. The catalyst preparation consisted of the adsorption of iron porphyrin precursor on CNT, silica layer overcoating, high-temperature pyrolysis, and silica layer etching, which yielded CNTs coated with thin layers of porphyrinic carbon (CNT/PC) catalysts. We found that the silica-coating step plays a decisive role in preferentially generating catalytically active Fe???Nx coordination sites, as revealed by temperature-controlled in situ X-ray absorption spectroscopy (XAS). The CNT/PC catalyst contained higher concentration of active Fe???Nx sites compared to the CNT/PC prepared without silica coating. The CNT/PC showed very high ORR activity and excellent stability in alkaline media. Importantly, an alkaline AEMFC with a CNT/PC-based cathode exhibited the highest current and power densities among NPMC-based AEMFCs. In addition, a CNT/PC-based cathode exhibited a high volumetric current density of 320 A cm???3 in acidic proton exchange membrane fuel cell. We also demonstrated the general applicability of this synthetic strategy to other carbon supports. Chapter 4 describes the investigation of active site structures of bifunctional oxygen electrode catalysts based on cobalt oxide (CoOx) under reaction conditions. Size-controlled (3???10 nm) cobalt oxide nanoparticles (CoOx NPs) supported on CNT were prepared, and served as model catalysts. Electrochemical in situ XAS suggested that the initial Co3O4 or CoO phase was transformed to Co3O4???CoOOH core???shell structures under the ORR and OER conditions regardless of particle sizes. Combined with the in situ XAS, cyclic voltammetry study revealed that Co2+/Co3+ and Co3+/Co4+ redox transitions are involved in the ORR and OER, respectively. We further examined the size-dependent electrocatalytic activities. The OER activity increased with decreasing NP size, which correlated to the larger amount of Co(III) species and larger surface area in smaller NPs. For the ORR, no particle size dependence was foundthe CoOx NPs mainly played an auxiliary role, promoting the reduction or disproportionation of peroxide generated from the two-electron reduction of O2 by CNT. In Chapter 5, we investigated the active site structure of NPMC comprising cobalt- and nitrogen-codoped carbon supported on CNT for the HER. For this purpose, CNT hybridized with cobalt phthalocyanic carbons (CNT/Co-PcC) were prepared via the silica coating strategy. A suite of Co???N/C catalysts that contain different concentrations of cobalt-based species (Co???Nx and Co@C) were prepared by controlling experimental parameters. The catalytic role of two Co-based sites for the HER in both acidic and alkaline media was investigated, which revealed that the HER activity in both media was linearly increased with the portion of the Co???Nx sites. This structure???activity relationship suggests that the Co???Nx sites are the major active sites while Co@C species have a minimal catalytic effect for the HER. In addition, reaction kinetics study over the CNT/Co-PcC catalyst allowed us to acquire a better understanding of the Co???Nx active sites for the HER.ope

Grid as a frame

A grid is a type of framework applied to an area in order to articulate information through coordinates and units. Nowadays, the world we experience has become overwhelmed by digital displays. How can we perceive the different form of reality when both experience and our perspective are shaped by digital representation? What if our life continues in virtual topography where I can see my GPS location, or in a rectangular camera frame instead of on the spherical earth? I walk with my feet touching the ground and I see the landscape around me, but still, now, I navigate myself in Google Maps to arrive at a destination. This mismatched experience of physicality and virtuality gives rise to a moment I have come to focus on: a break in perception

Development of a technology adoption and usage prediction tool for assistive technology for people with dementia

This article is available open access through the publisher’s website at the link below. Copyright @ The Authors 2013.In the current work, data gleaned from an assistive technology (reminding technology), which has been evaluated with people with Dementia over a period of several years was retrospectively studied to extract the factors that contributed to successful adoption. The aim was to develop a prediction model with the capability of prospectively assessing whether the assistive technology would be suitable for persons with Dementia (and their carer), based on user characteristics, needs and perceptions. Such a prediction tool has the ability to empower a formal carer to assess, through a very limited amount of questions, whether the technology will be adopted and used.EPSR

Conophytum crateriforme - a new dumpling from Namaqualand

Summary: A new taxon in the dwarf succulent genus Conophytum from Namaqualand, South Africa is described – Conophytum crateriforme. The plant is named for its distinctive bowl shape

Conophytum bachelorum and its relatives: the introduction of a new conophytum from Namaqualand, C. confusum.

Summary: A reassessment of a group of four closely related taxa of the dwarf succulent genus Conophytum from Namaqualand, South Africa has been undertaken. This has resulted in the description of a newly discovered taxon, namely Conophytum confusum

Simple coordination complex-derived three-dimensional mesoporous graphene as an efficient bifunctional oxygen electrocatalyst

3D mesoporous graphene (mesoG) was synthesized from [Ni<inf>2</inf>(EDTA)] (EDTA = ethylenediaminetetraacetate). The material is comprised of interconnected 4 nm-sized hollow carbon shells composed of 3-4 layers of graphene and exhibits high bifunctional electrocatalytic activity as well as high durability for use in oxygen evolution and reduction reactions. This journal is ??? 2015 The Royal Society of Chemistryopen11

Ocean warming, not acidification, controlled coccolithophore response during past greenhouse climate change

Current carbon dioxide emissions are an assumed threat to oceanic calcifying plankton (coccolithophores) not just due to rising sea-surface temperatures, but also because of ocean acidification (OA). This assessment is based on single species culture experiments that are now revealing complex, synergistic, and adaptive responses to such environmental change. Despite this complexity, there is still a widespread perception that coccolithophore calcification will be inhibited by OA. These plankton have an excellent fossil record, and so we can test for the impact of OA during geological carbon cycle events, providing the added advantages of exploring entire communities across real-world major climate perturbation and recovery. Here we target fossil coccolithophore groups (holococcoliths and braarudosphaerids) expected to exhibit greatest sensitivity to acidification because of their reliance on extracellular calcification. Across the Paleocene-Eocene Thermal Maximum (56 Ma) rapid warming event, the biogeography and abundance of these extracellular calcifiers shifted dramatically, disappearing entirely from low latitudes to become limited to cooler, lower saturation-state areas. By comparing these range shift data with the environmental parameters from an Earth system model, we show that the principal control on these range retractions was temperature, with survival maintained in high-latitude refugia, despite more adverse ocean chemistry conditions. Deleterious effects of OA were only evidenced when twinned with elevated temperatures

Who will use pre-exposure prophylaxis (PrEP) and why?: Understanding PrEP awareness and acceptability amongst men who have sex with men in the UK – a mixed methods study

Background: Recent clinical trials suggest that pre-exposure prophylaxis (PrEP) may reduce HIV transmission by up to 86% for men who have sex with men (MSM), whilst relatively high levels of PrEP acceptability have been reported to date. This study examines PrEP awareness amongst sub-groups of MSM communities and acceptability amongst MSM in a low prevalence region (Scotland, UK), using a mixed methods design. Methods: Quantitative surveys of n = 690 MSM recruited online via social and sociosexual media were analysed using descriptive statistics and multivariate logistic regression. In addition, n = 10 in-depth qualitative interviews with MSM were analysed thematically. Results: Under one third (29.7%) of MSM had heard of PrEP, with awareness related to living in large cities, degree level education, commercial gay scene use and reporting an HIV test in the last year. Just under half of participants (47.8%) were likely to use PrEP if it were available but there was no relationship between PrEP acceptability and previous PrEP awareness. Younger men (18–25 years) and those who report higher risk UAI were significantly more likely to say they would use PrEP. Qualitative data described specific PrEP scenarios, illustrating how risk, patterns of sexual practice and social relationships could affect motivation for and nature of PrEP use. Conclusion: These findings suggest substantial interest PrEP amongst MSM reporting HIV risk behaviours in Scotland. Given the Proud results, there is a strong case to investigate PrEP implementation within the UK. However, it appears that disparities in awareness have already emerged along traditional indicators of inequality. Our research identifies the need for comprehensive support when PrEP is introduced, including a key online component, to ensure equity of awareness across diverse MSM communities (e.g. by geography, education, gay scene use and HIV proximity), as well as to responding to the diverse informational and sexual health needs of all MSM communities