The structure of manganese dioxide-hydrogen insertion compounds and some related stability studies

Six synthetic manganese dioxides (coded SBPA, Faradiser WSZ, IBA no.14, IBA no.19, R2 and Faradiser M) covering the range of crystal structures exhibited by battery active materials were studied by XRD (X-Ray Diffraction) and FTIR (Fourier Transform Infra-Red) spectroscopy when H was inserted with organic reductants. Initial x-ray diffraction patterns (i.e. before H insertion) indicated a structural series, the γ-γt-MnO2 series. where γ-MnO2 designates the phase defined by de Wolff's intergrowth model. This model described γ-MnO2 as a random alternation of two types of layers derived from the known structures of the minerals ramsdellite and pyrolusite. γ-MnO2 may be characterised by one parameter, p, the pyrolusite type layer fraction. p=0 corresponds to ramsdellite whereas p=1 corresponds to pyrolusite. The additional structural defect responsible for the γ-γt-MnO2 series was found to be that of microtwinning in accordance with the model proposed by Pannetier et al. Material SBPA possessed a low degree of microtwinning with p=0.204±O.OO5 whereas typical battery active manganese dioxides IBA no.19 and R2 possessed x-ray diffraction patterns consistent with a high degree of microtwinning and p-0.2. The other materials, except Faradiser M, displayed x-ray diffraction patterns intermediate between those of SBPA and IBA no. 19/R2. Faradiser M possessed a high degree of microtwinning but with p-0.7. The most H inserted compounds (i.e. of composition MnOOH1.0) also formed an analogous structural series. the δ-δt-MnOOH series. δ-MnOOH may be described as a random alternation of two types of layers derived from the known structures of the minerals groutite and manganite which are reduced isostructural derivatives of ramsdellite and pyrolusite. δ-MnOOH was successfully analyzed for the concentration of (presumed) manganite type layer defects (m) in an analogous manner to that required to determine p, which confirmed the existence of reduced intergrowth structures. m was found to be less than p unless the H insertion reaction temperature was lowered (-2°C) in which case m=p. This was consistent with the observed precipitation of small amounts of γ-MnOOH when H was inserted with chemical reductants in non-aqueous solvents. The level of H insertion may be represented by the formula r in MnOOHr, where -0.1≤r≤1.0 (r starts at a value greater than zero due to the non-stoichiometry of battery active materials). H insertion into EMD (Electrodeposited Manganese Dioxide) R2 led to approximate isotropic lattice expansion in the H insertion region 0.11≤r≤0.80. This observation was consistent with a homogeneous solid state reduction with formation of a solid solution in which H+ and e- were mobile. In the region 0.80≤r≤1.01'new' non-moving peaks emerged characteristic of the final product while the original lines continued to move. The line shift indicated anisotropic lattice expansion. The 'new' non moving peaks could not be interpreted on the basis that a new phase was emerging. An explanation for this behaviour based on the properties of the defect crystal structure of the original material has been found. It involved identification of a type of x-ray line shift characteristic of random layer structures. The effects observed were consistent with random precipitation of δ-MnOOH micro-domains within the solid solution. The 'new lines' which emerged represented a re-emergence of lines originally overlapped with other lines due to the particular effects of microtwinning. The appearance of microdomains of the end product crystallizing within the solid solution implied that H+ and e- were no longer mobile in the crystal structure but located or 'frozen' in position. The presence of 'frozen' H (i.e δ-MnOOH micro-domains) was supported by measurements of FTIR band areas at wavenumber regions where OH vibration modes occurred. The onset of OH vibration modes with increasing H insertion supported the interpretation of the x-ray patterns. Interpretation of the FTIR spectra of material SBPA indicated no OH bond formation in the H insertion region 0.068≤r≤0.35 and OH bond formation in the region 0.35≤r≤0.882. Examination of the XRD patterns indicated heterogeneous solid state reduction had occurred in the H insertion region 0.40≤r≤0.882. The onset of OH bond formation at r=0.35 was interpreted as a necessary precursor to heterogeneous reduction starting at r=OAO. Heterogeneous reduction was presumed to have occurred by H location in an outer particulate layer which propagated into the bulk. H insertion into the remaining materials was interpreted in a similar manner. That is beyond a certain r in MnOOHr H location, as indicated by OH bond formation, led to crystallization of δ-MnOOH micro-domains which either randomly precipitated in the solid solution or they associated in such a way that led to heterogeneous reduction. The r in MnOOHr at which H started to locate appeared to depend on the relative rates at which H was inserted and diffused into the solid. H location occurred at r-0.20 for Faradiser M in contrast to R2 in which it located at r=0.80. A complementary study of the stability of the H inserted compounds in 7M KOH was carried out. Results from potential measurements, x-ray diffraction and SEM were obtained. Over a period of six weeks potential measurements indicated development of a heterogeneous potential at deep H insertion levels. X-ray diffraction and SEM signified formation of δ-MnO2 and γ-MnOOH. The results confirm the proposition of Holton et al. that H inserted compounds are unstable in KOH and disproportionate into δ-MnO2 and γ–MnOOH. This work removes doubt concerning the above proposition since formation of δ-MnO2 n their work was not simply the result of instability. The H insertion level at which instability was observed appeared related to the formation of δ-MnOOH micro-domains, particularly for R2 in which instability occurred between 0.80≤r≤1.0. This coincides with the oxidation state, MnO1.6, beyond which alkaline manganese batteries cease to deliver useful power on prolonged intermittent discharge. Faradiser M possessed the largest instability region (0.48≤r≤1.0) and would, on this basis, be unsuitable for alkaline manganese batteries

Bomber Offensive

War is essentially an affair of ethics as well as , economics and, though the economical aspect presses heavily on the people of the world today, the ethical aspect has continuously occupied the thoughts of mankind in an unceasing endeavour to diminish war\u27s inevitable horrors, and to limit and localize its effects. The advocates of air power , in urging their claim for precedence, took a firm stand, with a foot planted squarely on each of these bases

Analysis of textile impressions from pottery of the Selkirk composite

The boreal forest regions of Saskatchewan and Manitoba are characterized by Late Woodland period archaeological assemblages. Although the pottery associated with these assemblages exhibit textile impressed exteriors, little is known about the associated textile industry. In part, this is due to the lack of archaeological textiles. In order to describe the textile structures employed by these people, it is necessary to study their textile-impressed pottery. Two complexes within the Selkirk Composite, Pehonan/Keskatchewan and Kame Hills are known through several intensively excavated sites and a large number of pottery recoveries. Using textile attribute studies, data on 47 impressed vessels from 17 sites were collected. Supplemented by ethnographic and historical reports from neighbouring regions, textile structures are identified for both complexes. The most represented textile structure is twining. These identified structures verify the homogeneity of the Selkirk Composite. There are enough structural variations, however, to support the regional expressions of each complex. The impressed textiles are utilitarian in nature and played an integral part in pottery manufacture. Selkirk potters were expert craftpersons. This is reflected in their pottery and in the way they employed the textiles. Although the analysis is limited to textiles used in pottery construction, cursory textile comparisons indicate the Selkirk textiles have more similarity to those produced historically by Algonquians to the south

Kindertransport Recalls Broken Families

Providence College Department of Theatre, Dance & Film Review of Kindertransport in Providence college magazine, Summer 2000 by Elaine L. MacLean.https://digitalcommons.providence.edu/kinder_commentary/1000/thumbnail.jp

Reducing Employee Turnover in the Big Four Public Accounting Firms

Employee turnover is extremely costly to any business in terms of training costs and loss of pertinent knowledge and experience. This paper explores the contributors to the high rates of employee turnover seen in public accounting by focusing on the Big Four accounting firms, Deloitte, EY, KPMG, and PricewaterhouseCoopers. Employee retention is a factor of corresponding employee motivation, as seen through the analysis of popular motivational theories and their applications to a career in public accounting. This paper also delves into the possible contributors to the differences in retention rates between males and females in this occupation. Lastly, an analysis of current firm programs and initiatives is conducted, with suggestions for ulterior areas of focus and improvements to current programs. The popular motivational theories explored signify important areas of focus for current and suggested programs. The opportunities presented by effective and accessible mentors are of extreme importance to reducing turnover and aiding an employee in developing ownership over a firm’s mission. Additionally, stereotypes associated with females in the business world and the inherent work of public accounting inhibits young professionals from establishing longevity with a firm. The current programs offered by the Big Four firms are likely to be enhanced and improved upon by new generations of professionals entering into the higher ranks of leadership

Stage progression and neurological symptoms in Trypanosoma brucei rhodesiense sleeping sickness: role of the CNS inflammatory response

Background: Human African trypanosomiasis progresses from an early (hemolymphatic) stage, through CNS invasion to the late (meningoencephalitic) stage. In experimental infections disease progression is associated with neuroinflammatory responses and neurological symptoms, but this concept requires evaluation in African trypanosomiasis patients, where correct diagnosis of the disease stage is of critical therapeutic importance. Methodology/Principal Findings: This was a retrospective study on a cohort of 115 T.b.rhodesiense HAT patients recruited in Eastern Uganda. Paired plasma and CSF samples allowed the measurement of peripheral and CNS immunoglobulin and of CSF cytokine synthesis. Cytokine and immunoglobulin expression were evaluated in relation to disease duration, stage progression and neurological symptoms. Neurological symptoms were not related to stage progression (with the exception of moderate coma). Increases in CNS immunoglobulin, IL-10 and TNF-α synthesis were associated with stage progression and were mirrored by a reduction in TGF-β levels in the CSF. There were no significant associations between CNS immunoglobulin and cytokine production and neurological signs of disease with the exception of moderate coma cases. Within the study group we identified diagnostically early stage cases with no CSF pleocytosis but intrathecal immunoglobulin synthesis and diagnostically late stage cases with marginal CSF pleocytosis and no detectable trypanosomes in the CSF. Conclusions: Our results demonstrate that there is not a direct linkage between stage progression, neurological signs of infection and neuroinflammatory responses in rhodesiense HAT. Neurological signs are observed in both early and late stages, and while intrathecal immunoglobulin synthesis is associated with neurological signs, these are also observed in cases lacking a CNS inflammatory response. While there is an increase in inflammatory cytokine production with stage progression, this is paralleled by increases in CSF IL-10. As stage diagnostics, the CSF immunoglobulins and cytokines studied do not have sufficient sensitivity to be of clinical value

Old concepts, new challenges: adapting landscape-scale conservation to the twenty-first century

This is the final version of the article. Available from Springer Verlag via the DOI in this record.Landscape-scale approaches to conservation stem largely from the classic ideas of reserve design: encouraging bigger and more sites, enhancing connectivity among sites, and improving habitat quality. Trade-offs are imposed between these four strategies by the limited resources and opportunities available for conservation programmes, including the establishment and management of protected areas, and wildlife-friendly farming and forestry. Although debate regarding trade-offs between the size, number, connectivity and quality of protected areas was prevalent in the 1970–1990s, the implications of the same trade-offs for ongoing conservation responses to threats from accelerating environmental change have rarely been addressed. Here, we reassess the implications of reserve design theory for landscape-scale conservation, and present a blueprint to help practitioners to prioritise among the four strategies. We consider the new perspectives placed on landscape-scale conservation programmes by twenty-first century pressures including climate change, invasive species and the need to marry food security with biodiversity conservation. A framework of the situations under which available theory and evidence recommend that each of the four strategies be prioritized is provided, seeking to increase the clarity required for urgent conservation decision-making.L. Donaldson was supported by a Natural Environment Research Council (NERC) CASE studentship (Grant Number NE/L501669/1) in partnership with the Royal Society for the Protection of Birds (RSPB)