Properties of short polystyrene chains confined between two Gold surfaces through a combined Density Functional Theory and classical Molecular Dynamics approach

The properties of atactic short-chain polystyrene films confined between two parallel gold surfaces at a temperature of 503 K are investigated using a combination of density functional theory calculations and classical atomistic simulations. A classical Morse-type potential, used to describe the interaction between the polymer and the gold surface, was parameterized based on the results of density functional calculations. Several polystyrene films were studied, with thicknesses ranging from around 1-10 nm. The structural, conformational and dynamical properties of the films were analysed and compared to the properties of the bulk polystyrene systems. The dynamics of the polystyrene close to the surface was found to be significantly slower than in the bulk

Hierarchical multiscale modeling of polymer-solid interfaces: atomistic to coarse-grained description, and structural and conformational properties of polystyrene-gold systems

A hierarchical simulation approach was developed in order to study polystyrene films sandwiched between two parallel Au(111) surfaces. The coarse-grained potentials describing the interaction of polystyrene with the gold surface were developed systematically using constrained all-atom molecular simulations of a styrene trimer on the Au(111) surface. The model was validated by studying a 5 nm film of short (10mer) polystyrene chains using all-atom and coarse-grained molecular dynamics simulations. The density, structure and conformational properties of coarse-grained films were found to be in excellent agreement with all-atom ones. The coarse-grained model was then used to study the structural and conformational properties of roughly 10 nm and 20 nm thick films with 10, 50, 100 and 200mer chains. The width of the interphase region of the polymer films is property specific. The density profiles reached the bulk value around 1.5 nm from the interface, for all chain lengths. An estimate of the width of the interphase region based on the conformation tensor profile indicates that the interphase width is proportional to the square root of the chain length (number of monomers) and for 200mer chains the interphase width is approximately 6-9 nm

Governance: public governance to social innovation?

ArticleThis paper reviews governance and public governance related to an emerging area of policy interest – social innovation. The European Commission’s White Paper on European Governance (2001) focused on openness, participation, accountability, effectiveness and coherence in public policy as characteristics of good governance. The EC has prioritised social innovation to address policy problems. Yet, the extant literature and research on social innovation is sparse. The paper questions whether it is a new mode of governance which contributes to good governance or a continuum of neoliberal reforms of the state which alters the relationship between the state, market and civil society

Polymer adhesion: first-principles calculations of the adsorption of organic molecules onto Si surfaces

The structures and energetics of organic molecules adsorbed onto clean and H-passivated Si(001)-(2$\times$1) surfaces have been calculated using density functional theory. For benzene adsorbed on the clean Si surface the tight-bridge structure was found to be stable and the butterfly structure metastable. Both carbonic acid H$_2$CO$_3$ and propane C$_3$H$_8$ dissociate on contact with the surface. Passivation of the Si surface with H-atoms has a dramatic effect on the surface properties. The passivated surface is very inert and the binding energy of all the molecules is very weak.Comment: 8 pages, 13 figure

Co-governance or meta-bureaucracy? Perspectives of local governance 'partnership' in England and Scotland

This article assesses the nature of partnerships through the research site of local governance in England and Scotland, engaging a range of debates and literature around governance and meta-governance. The research used secondary data of local authority partnership working in England and Scotland as well as primary qualitative data from participant observation and interviews with senior officials of local authorities and partner organisations. There is little to suggest that English and Scottish practices are significantly at variance and the article advances an argument of meta-bureaucracy to describe partnerships' activities: that is to say, partnerships do not represent a growth of autonomous networks and governance arrangements but rather an extension of bureaucratic controls. State actors remain pre-eminent within increasingly formalised systems of 'partnership'

A hierarchical dualscale study of bisphenol-A-polycarbonate on a silicon surface : structure, dynamics and impurity diffusion

A previously developed and studied coarse-grained model is used to investigate the properties of bisphenol-A-polycarbonate (BPA-PC) in contact with the Si(001)-(2 x 1) surface. The surface interaction potentials are based on density functional calculations. Both a smooth wall potential and a site-dependent wall potential were used to represent the surface. For both types of surface potential it was found that only the chain ends adsorb and the density profiles and conformations in each case are similar. The site-dependent surface slows the dynamics of the polymer at the interface by an order of magnitude compared to the bulk dynamics for the chain lengths considered. The diffusion of non-adsorbing impurity particles for both surface potentials was investigated and the concentration and dynamics of the impurity particles were analysed

Polarization Enhancement in Short Period Superlattices via Interfacial Intermixing

The effect of intermixing at the interface of short period PbTiO$_3$/SrTiO$_3$ superlattices is studied using first-principles density functional theory. The results indicate that interfacial intermixing significantly enhances the polarization within the superlattice. This enhancement is directly related to the off-centering of Pb and Sr cations and can be explained through a discussion of interacting dipoles. This picture should be general for a wide range of multicomponent superlattices and may have important consequences for the design of ferroelectric devices.Comment: 4 pages, 6 figure

The role of senior public servants in South Africa : lessons for the future

Bibliography: leaves 293-303.The researcher has attempted to analyse the impact of transformation on the role of the most senior public servant in South Africa, the Director General. This required an analysis of the Director General's administrative and policy roles within the political-administrative interface. The aims of the research were firstly to provide a description of the role of the Director General in the South African public service and thereby provide an insight into the office of the Director General. Secondly, the aim was to evaluate the South African public service transformation process as well as changes which have taken place at Director General level. A third aim was to provide a normative framework of the political and administrative interface in the South African context, and finally to contribute to the analysis of public service senior management. Thus, three research questions were posed: I. What role did the Director General play in the pre-and post-1994 South African public service? 2. What is the administrative and political interface in South Africa? 3. What ought to be the administrative and political interface in South Africa? In order to answer these questions, literature was reviewed and interviews were conducted with Directors General who served at a national level during the pre-and post-1994 eras. An open and closed questionnaire was developed by the researcher in order to gather data, and the research is therefore original work. The research incorporated scientific principles of social science and is a qualitative study. The research findings can be summarised as follows. Directors General, both pre-and post-1994, have two basic roles, one of which is an administrative role, the other, a policy role. The administrative role of the Director General has not fundamentally changed over the past fifteen years. Directors General continue to be responsible for human and financial resources within their administrative capacity. Problems and issues identified in Director Generals' administrative capacity persist and need to be addressed by improving management capacity. The Director General's policy role appears to be changing. A trend has been identified which indicates that Directors General are playing less of a policy role and more of an administrative role. It appears that the political leadership is usurping the Director General's policy role. Although a political-administrative dichotomy has never existed in South Africa, the role of the Director General is becoming more politicised with the introduction of presidential appointments. The research concludes with recommendations for improving management capacity, and developing a more sustainable political-administrative interface. It is hoped that this research will assist the South African government in its efforts to improve the management capacity in the public service in order for it to deliver quality services to all South Africans in an increasingly complex global environment

A Comparison of Two Smart Cities: Singapore & Atlanta

This paper compares Singapore\u27s top-ranked smart city strategy to Atlanta, Georgia, a city that does not make a top smart city ranking but boasts internationally recognized smart city projects