Studies on Modification of Surface Properties in Polycarbonate (PC) Film Induced by DC Glow Discharge Plasma

The polycarbonate film (PC) surface was treated using glow discharge low-pressure air plasma. The modified surface was characterized by contact angle, FTIR, XRD, AFM, and XPS analysis. The surface-modified samples were further investigated using T-peel test for technical applications. The surface energy of the sample was estimated by measuring contact angle. The results show that, after plasma treatment, the root mean square (RMS) roughness of PC film was gradually increased with exposure time. Plasma treatment modified the chemical composition of the polymer surface and it made the surface to be highly hydrophilic. It was found that the air plasma treatment increases the polar component of PC film

New Agendas for Agricultural Research in Developing Countries: Policy Analysis and Institutional Implications

This article argues that the goals of agricultural research in poor countries have changed substantially over the last four decades. In particular they have broadened from the early (and narrow) emphasis on food production to a much wider agenda that includes poverty alleviation, environmental degradation, and social inclusion. Conversely, agricultural research systems have proved remarkably resistant to the concomitant need for changes in research focus. As a result many, at both the national and international level, are under great strain. In terms of public policy the article goes on to suggest that shortcomings of existing conceptual approaches to technology development could be supplemented by adopting analytical principles that view innovation in systemic terms. An approach where flows of knowledge between institutional nodes is a key to innovative performance (the “National Systems of Innovation” approach) is suggested as one such conceptual framework that might help supplement conventional policy analysis. An earlier version of this paper was presented at a workshop “New Policy Agendas for Agricultural Research: Implications for Institutional Arrangements” held on 28 March 2000 at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, India. The workshop was supported by the UK Department of International Development (DFID) Crop Post-Harvest Programme as an output of the project “Optimising Institutional Arrangements.

CaO–MgO–SiO2 glass ceramics: Transferred arc plasma (TAP) synthesis and microstructural characterization

In this paper, synthesis of CaO–MgO–SiO2 glass ceramic using transferred arc plasma (TAP) processingmethod is illustrated. Homogeneous mixture of 51.6% SiO2, 35.6% CaO and 12.8% MgO prepared by drymixing in a ball mill was kept in the anode well (which is the melting bed) of the 10 kW transferredarc plasma torch. It was melted in plasma at an operating power of 5 kW (by varying the processing timefor 3, 5 and 8 min). The melt was cooled to solidify by applying forced air on it. The resulting sampleswere characterized for microstructure and phase composition. The phases were identified by scanningelectron microscopy (SEM), using the back-scattered electron (BSE) image mode and X-ray diffraction(XRD) and energy dispersive X-ray analysis (EDX). The microstructure was examined using opticalmicroscopy (OM) and scanning electron microscopy. The micro-hardness, density and porosity measurementsfor the synthesized samples were carried out. Differential thermal analysis (DTA) was performedto study the thermal evolution. The results show the formation of diopside phase in the transferred arcplasma melted CaO–MgO–SiO2 glass ceramic system achieved with in a quite considerable short time ofplasma processing. The method indicated that TAP technique could be a promising, time saving and onestepmanufacturing process for the production of functional bulk glass ceramics

Bioactivity of thermal plasma synthesized bovine hydroxyapatite/glass ceramic composites

Bone injuries and failures often require the inception of implant biomaterials. Research in this area is receiving increasing attention worldwide. A variety of artificial bone materials, such as metals, polymeric materials, composites and ceramics, are being explored to replace diseased bones. Calcium phosphate ceramics are currently used as biomaterials for many applications in both dentistry and orthopedics. Bioactive silicate-based glasses show a higher bioactive behaviour than calcium phosphate materials. It is very interesting to study the mixtures of HA and silicate-based glasses. In the present study; natural bovine hydroxyapatite / SiO2–CaO–MgO glass composites were produced using the Transferred arc plasma (TAP) melting method. TAP melting route is a brisk process of preparation of glass-ceramics in which the raw materials are melted in the plasma and crystallization of the melt occurs while cooling down at a much faster rate in relatively short processing times compared to the conventional methods of manufacture of glass ceramics/composites. It is well known that; one essential step to the understanding of the biological events occurring at the bone tissue/material interface is the biological investigation by in vitro tests. Cell lines are commonly used for biocompatibility tests, and are very efficient because of their reproducibility and culture facility. In this study, we report the results of a study on the response of primary cultures of human fibroblast cells to TAP melted bioactive glass ceramics

Bioactivity of CaO–MgO–SiO2 glass ceramics synthesized using transferred arc plasma (TAP) process

Glass ceramic with a nominal composition of 35.6% CaO, 12.8% MgO and 51.6% SiO2 was prepared bytransferred arc plasma processing. The in vitro bioactivity of the plasma synthesized CaO–MgO–SiO2 glassceramic was examined for its biomedical applicability which was evaluated by immersion in simulated bodyfluid at 36.5 °C for several days. The apatite particles were found to be formed on the surface of the glassceramic and grew with the passage of soaking time. The simulated body fluid test results showed theformation of carbonated hydroxyapatite like layer on the surface of the glass ceramic. The cytocompatibilitywas evaluated through human fibroblast proliferation. The fibroblasts adhere, spread, and proliferate on theCaO–MgO–SiO2 glass ceramic, and the cell proliferation was more obvious