Improved adherence and spreading of Saos-2 cells on polypropylene surfaces achieved by surface texturing and carbon nitride coating

The adhesion and contact guidance of human primary osteogenic sarcoma cells (Saos-2) were characterized on smooth, microstructured (MST) and micro- and nano-structured (MNST) polypropylene (PP) and on the same samples with a silicon-doped carbon nitride (C₃N₄-Si) coating. Injection molding was used to pattern the PP surfaces and the coating was obtained by using ultra-short pulsed laser deposition (USPLD). Surfaces were characterized using atomic force microscopy and surface energy components were calculated according to the Owens-Wendt model. The results showed C₃N₄-Si coated surfaces to be significantly more hydrophilic than uncoated ones. In addition, there were 86% more cells in the smooth C₃N₄-Si coated PP compared to smooth uncoated PP and 551%/476% more cells with MST/MNST C₃N₄-Si coated PP than could be obtained with MST/MNST uncoated PP. Thus the adhesion, spreading and contact guidance of osteoblast-like cells was effectively improved by combining surface texturing and deposition of osteocompatible C₃N₄-Si coating.     

Silane-crosslinking of recycled low-density polyethylene/wood composites

The aim of this work was to study silane-crosslinking of recycled low-density polyethylene wood composites and its effect on composites properties. The composites were produced in a one-step twin-screw extrusion process and the silane–peroxide solution was pumped into the extruder. Degree of crosslinking, mechanical properties, short-term creep, fractured surfaces and nature of crosslinking were studied to understand the relationship between composite structure and properties. The results showed that crosslinked composite strength, toughness and creep resistance were improved compared to uncrosslinked composites. The flexural strength was doubled compared to uncrosslinked samples and the creep strain was reduced. The crosslinked composites stored under room conditions showed the highest strength, whereas storage in a sauna resulted in a higher degree of crosslinking. The Fourier transform infrared spectroscopy indicated formation of silane-bridges between wood and polyethylene, accordingly improving the interfacial adhesion between the wood and LDPE. The low concentration of peroxide in the silane-solution was shown to be a preferred composition to limit unintentional crosslinking during the process.     

The influence of fibre microstructure on fibre breakage and mechanical properties of natural fibre reinforced polypropylene

The aim of the study was to investigate the influence of fibre morphology of different natural fibres on the composites mechanical properties and on the fibre breakage due to extrusion process. The composite materials were manufactured using LTF (long fibre thermoplastic) extrusion and compression moulding and the used fibres were sisal, banana, jute and flax, and the matrix was a polypropylene. The results showed that sisal composites had the best impact properties and the longest fibres after the extrusion. Generally, the composites flexural stiffness was increased with increased fibre content for all fibres, being highest for flax composites. The flexural strength was not affected by the addition of fibres because of the low compatibility. The addition of 2 wt.% maleated polypropylene significantly improved the composites properties. Unlike the other three fibres, flax fibres were separated into individual elementary fibres during the process due to enzymatic retting and low lignin content.     

Influence of wood flour moisture content on the degree of silane-crosslinking and its relationship to structure–property relations of wood–thermoplastic composites

The objective of this work was to examine how the moisture content of wood flour affects the degree of crosslinking when producing silane-crosslinked wood–thermoplastic composites. Crosslinked composites were produced by adding a silane solution to the compounding process of wood flour and polyethylene. Crosslinked composites of pre-dried as well as non-dried wood flour were prepared and their degree of crosslinking at various storage conditions was determined. Mechanical properties and the creep response of the crosslinked composites were tested in order to establish structure–properties relations. The results showed that all crosslinked composites displayed higher strengths and lower creep responses compared with non-crosslinked control samples. However, the degree and rate of crosslinking proved to be lower when a larger amount of moisture was present in the compounding process. It was concluded that the silane-grafting yield was lower when wood flour of a higher moisture content was used.     

Dislocations structure investigation in neutron irradiated silicon detectors using AFM and microhardness measurements

The structure, microhardness and deformation character for silicon detectors were investigated following a neutron irradiation, using optical and atomic force (AFM) microscopes. The results of these investigations have given an important contribution to the understanding of silicon damage process by neutron irradiation. It was shown that in the interval of neutron fluences 9.9×10¹⁰≤Φ≤3.12×10¹⁵ n/cm², the shape of damage is accumulative (from small punctual to large defects). Abrupt changes of microstructure together with the electrical and mechanical properties [Bosetti M, Croitoru N, Furetta C, Pensotti S, Rancoita M, Rattaggi M, Redaelli M, Seidman A. Nucl Instr Methods B 1995;95:21; Croitoru N, Gambirasio A, Rancoita PG, Seidman A. Nucl Instr Methods B 1996;111:297; Croitoru N, Rancoita G, Rattaggi M, Rossi M, Seidman A. Nucl Instr Methods B 1996;114:120; Fretwurst N, Claussen N, Croitoru N, Papendick B, Pein U, Schatz H, Schultz T, Wunstorf R. Nucl Instr Methods A 1993;326:357; Croitoru N, Dahan R, Rancoita PG, Rattaggi M, Rossi G, Seidman A. Nucl Instr Methods B 1997;124:542], were found for Φ≥10¹⁴ n/cm². Different kinds of defects (dislocations and interstitials) and their complexes appeared under neutron irradiation. For all fluences the regions (“White” — “W”) with a microhardness smaller than in nonirradiated silicon were observed. Microhardness is larger in the regions where the concentration of dislocation loops is high. The “W” regions have a small number of the dislocations loops, and single punctual defects were seen there using atomic force microscope. The dislocation loops are placed in specific (“Black” — “B”) regions, which increase in size with the increase of neutron fluence due to a process of vacancies and interstitials accumulation.     

Adverse consequences of access to individuals’ information: an analysis of perceptions and the scope of organisational influence

Organisations are highly interested in collecting and analysing customer data to enhance their service offerings and customer interaction. However, individuals increasingly fear how such practices may negatively affect them. Although previous studies have investigated individuals’ concerns about information privacy practices, the adverse consequences people associate with external actors accessing their personal information remain unclear. To mitigate customers’ fears, organisations need to know which adverse consequences individuals are afraid of and how to address those negative perceptions. To investigate this topic, we conducted 22 focus groups with 119 participants. We developed a comprehensive conceptualisation and categorisation of individuals’ perceived adverse consequences of access to their information that includes seven types of consequences: psychological, social, career-related, physical, resource-related, prosecution-related, and freedom-related. Although individuals may limit their interactions with an organisation owing to consequences they associate with both the organisation and other actors, organisations can apply preventive and corrective mechanisms to mitigate some of these negative perceptions. However, organisations’ scope of influence is limited and some fears may be mitigated only by individuals themselves or government regulation, if at all.     

Integrated Water Resources Management along the Senegal River: Introducing an Analytical Framework

Integrated water resources management has become a trendy paradigm, although the issue is anything but new. In West Africa the past few decades have been rich with such attempts. Along the Senegal River their success has been very limited. The situation has instead polarized strongly across the dilemma of whether to prioritize a few macro-scale development goals or to develop the livelihood of the poor along the river. One of the crucial steps to move on is to develop a clear and transparent formulation of the problem. An approach that uses Bayesian networks is presented and applied in this study.     

Defining the relationships between IT service management and IT service governance

IT service provider organizations need both IT service management (ITSM) and IT service governance (ITSG) to ensure successful service provision for their customers. However, current service science literature has not adequately addressed how these activities differ from each other. Focusing solely on IT service management and ignoring service governance aspects may cause difficulties in measuring the performance of service management, defining and deploying the roles and responsibilities of service management, allocating the resources for right service improvements and adopting the service-oriented process culture. The research problem of this study is: How does IT service management differ from IT service governance? The main contribution of the study is a framework for IT service governance and a roadmap of IT service management frameworks and standards that can be utilized in establishing IT service governance activities. The theory-based framework is validated in an IT service change management case study with five Finnish IT service provider organizations. The results of this study may be used by top management, service directors and the IT service managers of IT service companies to better identify different aspects of IT service management and IT service governance.