Synthesis, Structure and Properties of Mixed Metal Oxides: From Pyrochlores to Fluorites

Introduction and Literature Review: Different families of oxide ion conductors and their applications are discussed. Experimental and Characterisation Methods: The synthetic methods and characterisation techniques used throughout this thesis are described. Synthesis, Structure and Transport Properties of Bi2Zr2-xTixO7 Phases: The characterisation of Bi2Zr2-xTixO7 compounds is reported for the first time. An increase in conductivity of 3 orders of magnitude is found for the Zr- rich end member. Bi2Ti2O7, which adopts centrosymmetric space group Fd-3m has been found to be SHG active. Structure Solution of beta-Bi2Sn2O7 and Properties of Bi2Sn2O7 Based Materials: Analysis of synchrotron powder X-ray and powder neutron diffraction data has shown for the first time that beta-Bi2Sn2O7 is not cubic and has a monoclinic structure, most likely in space group Pc. The effect of doping in both Bi2Sn2O7 and Bi2ScNbO7 on their respective conductivities has been explored. Synthesis and Characterisation of Nd2Zr2O7: A range of average and local structural techniques have been used to demonstrate that Nd2Zr2O7 prepared by wet-chemistry routes adopts the fluorite-type structure, as opposed to the pyrochlore structure adopted by samples synthesised by solid state methods. Synthesis, Characterisation, Simulations and Properties of Bi6WO12 and Related Oxide Ion Conductors: We report for the first time details of DFT molecular dynamics simulations to probe the oxide ion conduction pathways in the oxide ion conductor Bi6WO12. Appropriate doping has led to enhancements in oxide ion conductivity. Simulations, Characterisation and Properties of New Bismuth Vanadate Oxide Ion Conductors: DFT molecular dynamics simulations carried out on Bi19V2O33.5 have revealed the O2- migration pathways in this material with exceptional ionic conductivity. The synthesis and characterisation of new doped bismuth vanadates with formula Bi19-xMxV2O33.5-x/2 (M = Ca2+ or Sr2+), also excellent oxide ion conductors, is reported. Overall Conclusions and Suggestions for Future Work: This briefly reviews the conclusions and makes suggestions for further work

A comprehensive systematic review of the impact of planned interventions offered to pregnant women who have requested a caesarean section as a result of tokophobia (fear of childbirth)

Background: Tokophobia, a deep‐seated fear of childbirth, causes women emotional anguish and affects the mother‐baby relationship. It can result in women avoiding future pregnancies or requesting caesarean section. This review examines evidence for the effectiveness of planned interventions in women with okophobia in both reducing requests for caesarean section and in ameliorating maternal distress. Objectives: 1) To synthesise the best available quantitative evidence for the effectiveness of planned interventions in reducing: a) fear/anxiety in tokophobic women, b) planned caesarean sections 2) To synthesise the best available qualitative evidence relating to the experiences of tokophobic women who request a caesarean section, particularly satisfaction with interventions and the childbirth experience. Inclusion criteria: This review considered studies that included pregnant women requesting a caesarean section for tokophobia in the absence of medical (or obstetric) indications who were offered a planned intervention. Search strategy: The literature search focused on published and unpublished studies in English distributed between January 1990 and April 2012. An initial limited database search was undertaken to identify keywords, followed by an extensive search of relevant databases and potential grey material. Methodological quality: Assessment for methodological quality was carried out independently by two reviewers using the standardised appraisal tools from the Joanna Briggs Institute. Data extraction: Data were extracted from papers included in the review using the standardised data extraction tool from the Joanna Briggs Institute. Data synthesis: Statistical meta‐analysis was not possible due to heterogeneity. Therefore, a narrative summary of the data was undertaken. Results: Nine quantitative papers (comprising eight studies: one randomised controlled trial, five case control studies and two descriptive case series) were included; two of these papers appertained to the same study. No qualitative papers were found. Definitions for tokophobia varied. Samples were confounded by the inclusion of women with complex obstetric histories or with mental health issues. Comparison groups were sometimes non‐tokophobic women. Interventions were complex and descriptions sometimes lacked clarity. Although the randomised controlled trial found no difference in birth choices between samples, a group therapy intervention predisposed women to vaginal birth. One study measured whether interventions reduced fear, finding that they did. Four studies explored satisfaction with the intervention. In three cases interventions were evaluated positively. These involved midwifery input and birth planning. Conclusion: More research is needed to identify how tokophobic women might be helped. Current guidelines should be upheld for the time being, in the absence of further evidence. Implications for practice: Due to the heterogeneous nature of the research it is impossible at this stage to draw conclusions for practice. Implications for research: Due to ethical concerns about randomising tokophobic women to non‐treatment groups, innovative research designs should be considered. More research is needed on the effectiveness of group interventions and the role of midwives in administering interventions. A standard, measurable definition for tokophobia is needed and careful documentation and differential analysis of women's parity, mental health and obstetric status should be made. Outcomes should include fear reduction. Satisfaction and birth outcome should be measured on more than one occasion

Housing Conditions in Palestinian Refugee Camps, Jordan

This paper evaluates the quality of housing in a Palestinian refugee camp in Jordan. More than two million registered refugees live in Jordan, most of whom living in thirteen refugee camps established in the late 1960s following the Arab-Israeli conflict of 1967. Many of these camps are characterized by poor living conditions and associated health, social and environmental problems. However, there is scant empirical evidence regarding the quality of the housing in these camps. This paper addresses this gap by reporting on the findings of a questionnaire survey of 382 household units in Baqa’a Camp, the largest of the camps. The quantitative survey was triangulated by a series of extensive fieldwork visits to the area. Findings reveal that the housing in the camp is generally substandard. Poor structure and maintenance are key problems and this paper identifies and discusses various challenges, political and practical, that stand in the way of housing improvements. The paper concludes by suggesting that new models of ownership and responsibility need to be forged between the stakeholders in order to break the current stalemate of inaction

The Mechanism of Oxide Ion Conductivity in Bismuth Rhenium Oxide, Bi28Re2O49

We have carried out a combined experimental and computational study of oxide ion conductor Bi28Re2O49, with the aim of elucidating the conductivity mechanisms and pathways in this material. Single crystals of Bi28Re2O49 were grown from melt and the structure was investigated for the first time by single crystal X-ray diffraction. The structural model obtained is consistent with the Re atoms in Bi28Re2O49 being both four- and six-coordinate, in a 3:1 ratio, in agreement with previous EXAFS and IR spectroscopy studies. The thermal displacement parameters of the oxygen atoms bonded to Re suggest substantial disorder of the Re coordination polyhedra. Ab-initio molecular dynamics simulations were performed to probe the oxide ion migration pathways in Bi28Re2O49 and the roles of the Bisingle bondO and Resingle bondO sublattices. The key conclusion is that the ability of Re to support variable coordination environments is vitally important in Bi28Re2O49; it provides a mechanism for ‘self-doping’ of the structure, i.e. the creation of O2 − vacancies in the fluorite-like Bisingle bondO sublattice by exchange of O atoms with the Resingle bondO sublattice, and the subsequent increase of the average coordination number of Re. All three crystallographically unique oxygen sites in the Bisingle bondO sublattice play roles in the ionic migration processes, by facilitating the O2 − exchange between the ReOx groups and by contributing to the O2 − diffusion via the vacancy-hopping mechanisms

Synthesis, structure and tunability of zero dimensional organic-inorganic metal halides utilising the m-xylylenediammonium cation: MXD2PbI6, MXDBiI5, and MXD3Bi2Br12·2H2O

JLP thanks the University of St Andrews for funding and the Carnegie Trust for a Research Incentive Grant (RIG008653). We thank EPSRC for funding (EP/T019298/1 and EP/R023751/1).Over the past decade, the efficiency of photovoltaic devices based on CH3NH3PbI3 have dramatically increased. This has driven research efforts in all areas, from the discovery of materials to film processing to long-term device stability studies. Here, we report the synthesis and structure of three new “zero dimensional” organic–inorganic metal halides which use the meta-xylylenediammonium (MXD) cation: MXD2PbI6, MXDBiI5, and (MXD)3Bi2Br12·2H2O. The different structures of the new materials lead to compounds with a range of band gaps with MXDBiI5 having the lowest at 2.15 eV. We have explored the tunabilty of MXDBiI5 through halide substitution by preparing a series of samples with composition MXDBiI5–xBrx and determined the halide content using energy dispersive X-ray spectroscopy. A large range of solid solution is obtained in MXDBiI5–xBrx, resulting in the formation of single-phase materials for bromine contents from x = 0 to 3.71 (iodine contents from 1.29 to 5). This highlights the fact that zero-dimensional organic–inorganic halides are highly tunable, in a similar manner to the higher-dimensional perovskite counterparts. Such new materials open up the opportunity for further studies of the physics and optoelectronic properties of these materials.Publisher PDFPeer reviewe

Synthesis and electrochemical study of CoNi2S4 as a novel cathode material in a primary Li thermal battery

The authors acknowledge support and contribution from AWE Plc for this work, and thank the STFC for neutron diffraction beam-time.In this work CoNi2S4 was investigated as a candidate cathode material for Li thermal batteries. The CoNi2S4 was synthesized by a solid state reaction at 550◦C in a sealed quartz tube. Neutron powder diffraction was utilized to confirm normal spinel structure up to 200◦C, however, there was cation disorder above this temperature. The electrochemical properties of the batteries were investigated at 500◦C by galvanostatic discharge to elucidate the mechanism and the products NiS, Co3S4 and Co9S8 of the discharge mechanism were confirmed using powder X-ray diffraction. CoNi2S4 exhibits two voltage plateaus vs Li13Si4 at 500◦C, one at 1.75 V and the second at 1.50 V. CoNi2S4 has an overall capacity of 318 mA h g−1 from OCV 2.58 V to 1.25 V vs Li13Si4 which is comparable to that of the well-known metal disulfidesPublisher PDFPeer reviewe

Zirconium trisulfide as a promising cathode material for Li primary thermal batteries

In this work ZrS3 has been synthesized by solid state reaction in a sealed quartz tube and investigated as a candidate cathode material in Li thermal batteries. The structure of ZrS3 before and after cell testing has been studied using powder X-ray diffraction. A new spinel related material, LiZr2S4, has been identified as the product of the electrochemical process, which can be indexed to a = 10.452(8) Å cubic unit cell. The electrochemical properties of the batteries were investigated at 500 °C against Li13Si4 by galvanostatic discharge and galvanostatic intermittent titration technique (GITT). In a thermal Li cell at 500 °C a single voltage plateau of 1.70 V at a current density of 11 mA/cm2 was achieved with capacity of 357 mA h g-1. Therefore ZrS3 material has some promise as a cathode for Li thermal batteries.Publisher PDFPeer reviewe

The Health Education Research Experience (HERE) program metadata dataset

Undergraduate subject pools are prevalent across disciplines in the United States. The Health Education Research Experience (HERE) Program was the first known course-based subject pool entirely managed and conducted online for online students enrolled in an introductory health education/health promotion course. The program was conducted within five semesters from Spring 2012 through Summer 2013. The HERE Program encompassed 13 studies embedded in two sections of an undergraduate online course at the University of Florida. The studies were all related to course topics and current research topics in health education/promotion (as identified through the Healthy People 2020 Framework). The topics ranged from the relatively less sensitive health aspects of college life (i.e., technology use) to studies assessing more sensitive health topics (i.e., intimate partner violence and sexual assault). In alignment with a best practice in survey design, the HERE Program's survey instruments included one metadata item embedded in each survey to identify which devices students used to complete the surveys. Understanding which devices students used for survey completion has ramifications for survey designers and survey researchers. In contrast to the relative uniformity of pen and paper surveys and control of the survey completion environment, online surveys may not look identical across personal devices and may be completed in increasingly varied environments. All studies, study procedures and protocols, and metadata collection procedures were approved by the university's Institutional Review Board. The data presented here were extracted from each survey's data files and aggregated. The aggregated metadata are available through Mendeley Data in a.csv file for widespread access. Descriptive statistics are presented in tables. The data provided in this article will benefit researchers interested in survey methodology, questionnaire design, modes of survey collection, and survey metadata. The data are hosted in the following Mendeley Data repository: https://data.mendeley.com/datasets/ht9jmd3cdt/2