164,027 research outputs found

    Comparative study of osteogenic activity of multilayers made of synthetic and biogenic polyelectrolytes

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    Polyelectrolyte multilayer (PEM) coatings on biomaterials are applied to tailor adhesion, growth, and function of cells on biomedical implants. Here, biogenic and synthetic polyelectrolytes (PEL) are used for layer-by-layer assembly to study the osteogenic activity of PEM with human osteosarcoma MG-63 cells in a comparative manner. Formation of PEM is achieved with biogenic PEL fibrinogen (FBG) and poly-l-lysine (PLL) as well as biotinylated chondroitin sulfate (BCS) and avidin (AVI), while poly(allylamine hydrochloride) (PAH) and polystyrene sulfonate (PSS) represent a fully synthetic PEM used as a reference system here. Surface plasmon resonance measurements show highest layer mass for FBG/PLL and similar for PSS/PAH and BCS/AVI systems, while water contact angle and zeta potential measurements indicate larger differences for PSS/PAH and FBG/PLL but not for BCS/AVI multilayers. All PEM systems support cell adhesion and growth and promote osteogenic differentiation as well. However, FBG/PLL layers are superior regarding MG-63 cell adhesion during short-term culture, while the BCS/AVI system increases alkaline phosphatase activity in long-term culture. Particularly, a multilayer system based on affinity interaction like BCS/AVI may be useful for controlled presentation of biotinylated growth factors to promote growth and differentiation of cells for biomedical applications

    Asia-Europe Meeting: Contemporary Challenges and the Way Forward. Avia Policy Brief Issue 2019 No. 12 August 2019

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    The Asia-Europe Meeting (ASEM) was launched in 1996. Since its establishment, ASEM has experienced expansion of membership and a broadening of the scope of meetings and events. ā– ASEM is an informal forum for dialogue that is meant to be candid and comprehensive but often ended being quite scripted. ā– ASEM has been criticized as merely talk shops with no specific or concrete deliverables, and it has low public visibility and profile. ā– In the current uncertain and volatile world, ASEM could fade into oblivion if it maintains the current practices of informal and low-key engagement. ā– To make ASEM relevant in a more complex and contested world, there is a need to rethink ASEMā€™s objectives and modus operandi. ā– ASEM can be transformed into a more dynamic and vibrant ā€œmarketplaceā€ where ideas and actions flow

    Avi Rubin, Ottoman Nizamiye courts: law and modernity

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    This article is a book review on Avi Rubin's study, titled "Ottoman Nizamiye Courts. Law and Modernity

    Electromagnetic propagation through non-dissipative and dissipative barriers : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Physics at Massey University, Palmerston North, New Zealand

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    A Matlab simulation was developed to help visualise and investigate electromagnetic tunnelling through particular non-dissipative and dissipative barriers within a waveguide. The theory behind the simulation is based on a transmission line model that accurately predicts experimental results and is shown to be equivalent to previous numerical and quantum tunnelling models. A few useful speeds referring to electromagnetic waves have been defined and utilised to calculate die speeds at which different incident time signals penetrate electromagnetic barriers. Due to bandwidth restrictions, the created incident time signals had wavepacket properties. The importance of resampling an oscillating signal at the appropriate frequency to avoid aliasing has been recognised. The definition and creation of matched signals that can penetrate long barriers yet remain a single pulse have been investigated. Such signals will have no practical application since the attenuation will deem the transmitted signals immeasurable. However, the speeds through these larger barrier lengths will have a smaller uncertainty since the time delays are longer. Most of the signal distortion depends only on the barrier interfaces rather than the barrier length. Penetration through dissipative barriers gives speeds below the vacuum speed of light for all barrier lengths investigated. Faster than light speeds are however predicted for penetration through non-dissipative barriers greater than about 4cm

    Phenomenology: Basing Knowledge on Appearance

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    Phenomenology is the study of appearance as such. It is a branch of both Ontology and Epistemology, since appearing is being known. By an ā€˜appearanceā€™ is meant any existent which impinges on consciousness, anything cognized, irrespective of any judgment as to whether it be ā€˜realā€™ or ā€˜illusory.ā€™ The evaluation of a particular appearance as a reality or an illusion is a complex process, involving inductive and deductive logical principles and activities. Opinion has to earn the status of strict knowledge. Knowledge develops from appearances, which may be: (a) objects of perception, i.e. concrete phenomena in the physical or mental domains; (b) objects of intuition, i.e. oneā€™s subjective self, cognitions, volitions and valuations (non-phenomenal concretes); and/or (c) objects of conception, i.e. simple or complex abstracts of preceding appearances. Abstraction relies on apprehensions of sameness and difference between appearances (including received or projected appearances, and projected negations of appearances). Coherence in knowledge (perceptual, intuitive and conceptual) is maintained by apprehensions of compatibility or incompatibility. Words facilitate our construction of conceptual knowledge, thanks to their intentionality. The abstract concepts most words intend are common characters or behaviors of particulars (concrete material, mental or subjective experiences). Granting everything in the world is reducible to waves, ā€˜universalsā€™ would be equalities or proportionalities in the measures of the features, motions and interrelations of particular waves. Such a theory of universals would elucidate sensation and memory. In attempting to retrace the development of conceptual knowledge from experience, we may refer to certain major organizing principles. It is also important to keep track of the order of things in such development, interrelating specific concepts and specific experiences. By proposing a precise sequence of events, we avoid certain logical fallacies and are challenged to try and answer certain crucial questions in more detail. Many more topics are discussed in the present collection of essays, including selfhood, adduction and other logical issues, the status of mathematical concepts and theology
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