Role of Surface Reactivity in Processing and Performance of Magnesium Alloys

2015 ◽  
Vol 828-829 ◽  
pp. 401-406 ◽  
Author(s):  
Frank Czerwinski
Keyword(s):  
Magnesium Alloys ◽  
Surface Reactivity ◽  
Surface Oxide ◽  
Diffusion Characteristics ◽  
Component Manufacturing ◽  
And Performance ◽  
General Aspects ◽  
Liquid States ◽  
And Control

The surface reactivity of magnesium alloys at high temperatures required for their processing in solid, semisolid and liquid states is reviewed emphasizing presently existing barriers of its understanding and control. In addition to general aspects of magnesium oxidation, other forms of reactivity such as ignition and flammability are discussed. Since surface oxide, composed of pure MgO, does not offer a sufficient protection, operations of raw alloy melting and component manufacturing require protective atmospheres what has detrimental implications on process economy and product performance. Efforts to develop ignition resistant magnesium alloys through modification of their chemistry are described with a particular role of rare earths and other elements with high affinity to oxygen. It is concluded that all forms of magnesium reactivity in solid and liquid state could be explained through diffusion characteristics of surface oxide formed during processing and service.

The role of copper ions in hydrogen peroxide bleaching: Their origin, removal, and effect on pulp quality

TAPPI Journal ◽  
2012 ◽  
Vol 11 (7) ◽  
pp. 37-46 ◽  
Author(s):  
PEDRO E.G. LOUREIRO ◽  
SANDRINE DUARTE ◽  
DMITRY V. EVTUGUIN ◽  
M. GRAÇA V.S. CARVALHO
Keyword(s):  
Hydrogen Peroxide ◽  
Copper Ions ◽  
Peroxide Bleaching ◽  
Metals Removal ◽  
Peroxide Decomposition ◽  
Equipment Corrosion ◽  
And Performance ◽  
And Control ◽  
Main Effects

This study puts particular emphasis on the role of copper ions in the performance of hydrogen peroxide bleaching (P-stage). Owing to their variable levels across the bleaching line due to washing filtrates, bleaching reagents, and equipment corrosion, these ions can play a major role in hydrogen peroxide decomposition and be detrimental to polysaccharide integrity. In this study, a Cu-contaminated D0(EOP)D1 prebleached pulp was subjected to an acidic washing (A-stage) or chelation (Q-stage) before the alkaline P-stage. The objective was to understand the isolated and combined role of copper ions in peroxide bleaching performance. By applying an experimental design, it was possible to identify the main effects of the pretreatment variables on the extent of metals removal and performance of the P-stage. The acid treatment was unsuccessful in terms of complete copper removal, magnesium preservation, and control of hydrogen peroxide consumption in the following P-stage. Increasing reaction temperature and time of the acidic A-stage improved the brightness stability of the D0(EOP)D1AP bleached pulp. The optimum conditions for chelation pretreatment to maximize the brightness gains obtained in the subsequent P-stage with the lowest peroxide consumption were 0.4% diethylenetriaminepentaacetic acid (DTPA), 80ºC, and 4.5 pH.

scholarly journals THE ROLE OF TRUST IN RELATIONSHIP DEVELOPMENT AND PERFORMANCE IMPROVEMENT

2015 ◽  
Vol 21 (7) ◽  
pp. 845-853 ◽  
Author(s):  
Xianhai Meng
Keyword(s):  
Questionnaire Survey ◽  
Significant Contribution ◽  
Major Influence ◽  
Monitoring And Control ◽  
Collaborative Relationships ◽  
New Approach ◽  
And Performance ◽  
Qualitative Methodologies ◽  
And Control

The importance of inter-organizational trust to project success has been increasingly highlighted in the construction industry. This study aims to explore the role of trust between project parties. It adopts a combination of quantitative and qualitative methodologies. Based on the analysis of the responses of a questionnaire survey, trust is demonstrated to have a significant contribution to the development of cooperative or collaborative relationships; fostering trust proves to have a major influence on the improvement of project performance; and some relationship and performance indicators are found to have closer associations with trust than others so that trust is more important to the development of relationship and the improvement of performance in these aspects. The analysis of questionnaire responses also provides significant evidence for the reduction in monitoring and control following the increase of mutual trust. The questionnaire survey is followed by a series of expert interviews, both of which contribute to the establishment of a model that links trust with relationship and performance and distinguishes the new approach that is based on trust from the traditional mechanism that relies on monitoring and control.

The role of management accounting and control in making professional organizations horizontal

2016 ◽  
Vol 29 (3) ◽  
pp. 428-451 ◽  
Author(s):  
Gustaf Kastberg ◽  
Sven Siverbo
Keyword(s):  
Management Accounting ◽  
Actor Network Theory ◽  
Professional Organizations ◽  
Professional Identities ◽  
Content Type ◽  
Swedish Health Care ◽  
And Performance ◽  
And Control ◽  
The Relationship

Purpose – In the last decade, greater attention has been paid to the role of management accounting and control (MAC) in making professional organizations more horizontal. The authors argue that earlier research has not shown how the interrelatedness between professional identities and MAC influences attempts to make organizations more horizontal. In this paper the authors respond to the call for more research on the relationship between horizontalization and accounting and control. The purpose of this paper is to contribute to the emerging literature on the relationship between accountability arrangements and professional identities. Design/methodology/approach – Theoretically the authors have an actor-network theory (ANT) approach. Empirically, the authors followed two episodes where actors at top management levels in two Swedish health care organizations introduced horizontalization. Findings – The two episodes support the view that the role of MAC when making professional organizations more horizontal is limited. Professionals dominate what happens at the operational level and they do not act on MAC rules and performance targets in opposition of their professional identity. However, in alliance with other interessement devices MAC may have a role in creating overflows, that is, pointing out imperfections in the existing frame. The authors noticed no signs that professionals developed hybrid identities as in previous research. Originality/value – The authors apply ANT to move beyond the commonly used contingency and new institutional sociology perspectives.

Surface Reactivity of Magnesium Alloys in Solid and Liquid States

2013 ◽  
Vol 765 ◽  
pp. 698-702 ◽  
Author(s):  
Frank Czerwinski
Keyword(s):  
Magnesium Alloys ◽  
Surface Reactivity ◽  
Metallic Surface ◽  
Surface Degradation ◽  
Outward Diffusion ◽  
Alloy Chemistry ◽  
Thin Oxide Films ◽  
Major Factors ◽  
Liquid States ◽  
Solid And Liquid States

The major factors, controlling surface degradation of magnesium alloys in oxygen‑containing atmospheres at temperatures of solid and liquid states, are reviewed. While thin oxide films, formed during initial stages, exhibit some protective behaviour, thick scales grown at high temperatures do not block the outward diffusion of metal ions, leading to non-protective oxidation. The high vapour pressure of magnesium increases surface degradation and reduces effectiveness of inert atmospheres. Thus, both the solid and liquid states rely on the formation of compact oxide layers on the metallic surface, suppressing evaporation and oxidation. The role of protective atmospheres and alloy chemistry in reducing surface reactivity is discussed.

Visual Criminology

2017 ◽  
Author(s):  
Michelle Brown
Keyword(s):  
Interdisciplinary Studies ◽  
Dark Tourism ◽  
Crime And Punishment ◽  
Social Documentary ◽  
And Performance ◽  
Social Orders ◽  
And Control ◽  
Urban Aesthetics ◽  
Data Visualizations

Visual criminology emerges from a call to rethink the manner in which images are reshaping the world and criminology as a project. The mobility, malleability, banality, speed, and scale of images and their distribution demand that we engage both old and new theories and methods. Visual criminologists pursue a refinement of concepts and tools as well as innovative new ones to tackle questions of crime, harm, culture, and control. Concerned with how ways of seeing are foundational to social orders, visual criminology gives close attention to the production of crime’s power and spectacle in the visual field and relies upon emergent conceptual terms and vocabularies to do so. It insists that it is no longer possible to understand crime and control separately from how they are represented. Visual criminology is born as an alternative academic space that is neither supplementary nor secondary to mainstream social science; rather, it calls us to understand the power of crime and punishment beyond the written and numeric registers of reports, studies, and research. The concerns of visual criminology are numerous. Visual criminologists are interested in the role of vision and the visual in the historical foundations of criminology as a discipline. They push crime and media scholars to investigate more deeply the role of the image itself, beyond conventional studies of crime and media. Using a growing and sophisticated set of theories, methods, and concepts, they track how the various optics of criminology and criminal justice (defined by disciplinary, institutional, and epistemological boundaries) are produced, culminating in popular and scientific perspectives that inevitably bring certain principles, claims, and possibilities into the line of vision and omit others. They also give attention to how these optics are contested and transgressed. Focal points of this work span a variety of media and artistic modes that continue to grow at an unprecedented rate: photodocumentary, photoethnography, new and social media, interactive and social documentary, architecture, data visualizations, design, conceptual and performance art, mixed media, theater, embodiment, spatialization, surveillance and aerial/satellite/drone technology, graffiti and urban aesthetics, ruins and dark tourism, models, exhibitions, and imaginative interventions to envision crime and punishment otherwise. Even as this visual focus expands the disciplinary tools and insights of criminology, it also broadens the field’s boundaries, drawing from a rich theoretical terrain of interdisciplinary studies.

Morphogenesis of a New Human Herpes-Type Virus Isolate (Sasha Virus)

1973 ◽  
Vol 31 ◽  
pp. 592-593
Author(s):  
R. F. Zeigel ◽  
W. Munyon
Keyword(s):  
Virus Isolate ◽  
Calf Serum ◽  
Uranyl Acetate ◽  
Human Herpes ◽  
Human Embryonic Lung ◽  
Human Herpes Virus ◽  
Intracytoplasmic Inclusions ◽  
Hel Cells ◽  
And Control

In continuing studies on the role of viruses in biochemical transformation, Dr. Munyon has succeeded in isolating a highly infectious human herpes virus. Fluids of buccal pustular lesions from Sasha Munyon (10 mo. old) uiere introduced into monolayer sheets of human embryonic lung (HEL) cell cultures propagated in Eagles’ medium containing 5% calf serum. After 18 hours the cells exhibited a dramatic C.P.E. (intranuclear vacuoles, peripheral patching of chromatin, intracytoplasmic inclusions). Control HEL cells failed to reflect similar changes. Infected and control HEL cells were scraped from plastic flasks at 18 hrs. of incubation and centrifuged at 1200 × g for 15 min. Resultant cell packs uiere fixed in Dalton's chrome osmium, and post-fixed in aqueous uranyl acetate. Figure 1 illustrates typical hexagonal herpes-type nucleocapsids within the intranuclear virogenic regions. The nucleocapsids are approximately 100 nm in diameter. Nuclear membrane “translocation” (budding) uias observed.

Trace nanoanalysis

1994 ◽  
Vol 52 ◽  
pp. 940-941
Author(s):  
D. E. Newbury ◽  
R. D. Leapman
Keyword(s):  
High Performance ◽  
Secondary Ion Mass Spectrometry ◽  
Detection Efficiency ◽  
Volume Element ◽  
And Performance ◽  
Trace Constituents ◽  
Secondary Ion ◽  
Concentration Levels ◽  
Structure Properties

Trace constituents, which can be very loosely defined as those present at concentration levels below 1 percent, often exert influence on structure, properties, and performance far greater than what might be estimated from their proportion alone. Defining the role of trace constituents in the microstructure, or indeed even determining their location, makes great demands on the available array of microanalytical tools. These demands become increasingly more challenging as the dimensions of the volume element to be probed become smaller. For example, a cubic volume element of silicon with an edge dimension of 1 micrometer contains approximately 5×1010 atoms. High performance secondary ion mass spectrometry (SIMS) can be used to measure trace constituents to levels of hundreds of parts per billion from such a volume element (e. g., detection of at least 100 atoms to give 10% reproducibility with an overall detection efficiency of 1%, considering ionization, transmission, and counting).

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