CERES :: Browsing by Author "Ramsden, Jeremy J."

Browsing by Author "Ramsden, Jeremy J."

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Open Access
The application of niobium and tantalum oxides for implant surface passivation.
(Jointly by, Collegium Basilea (Institute of Advanced Study) and Association of Modern Scientific Investigation., 2007) Starikov, V. V.; Starikova, S. L.; Mamalis, A. G.; Lavrynenko, S. N.; Ramsden, Jeremy J.
Despite the advantages of ceramics, with their high corrosion stability in vivo, most medical implant constructions are still made from metals [1]. To increase the corrosion stability of metals, different coatings are applied to the implant surfaces, typically such coatings are the oxides of the metals in the implants [2]. For an oxide film to have protective properties it must satisfy the following requirements: • to be unbroken and pore-free; • to have good adhesion with the metal; • to have a thermal expansion constant near to the value for the metal; • to be chemically inert in different environments; • to be hard and have minimal wear under load. The oxides of metals such as Al, Ti, Zr, Nb and Ta satisfy all these properties to some degree [3–5]. Indeed, some of these metal oxides are used in medicine independently without a metal substrate, such as implant constructions from sapphire (a single-crystal modification of Al2O3) [6, 7]. Titanium is the most widely used material for medical implant manufacture [8]. Its chemical passivity is provided by the oxide film (TiO2), covering the entire free surface; a result of titanium contact with air. But titanium is unable to satisfy all the requirements necessary for an implant material because of its insufficient corrosion stability [9–11]. The application of combined implants consisting of a metal base and a ceramic coating also does not give a complete solution to the problem, because of the low adhesion strength and fragility of ceramic coatings [12, 13].
Open Access
Attachment and spreading of human embryonal carcinoma stem cells on nanosurfaces monitored by optical waveguides
(2008-06-05T00:00:00Z) Aref, Amirreza; Horvath, R.; Ansari, Farahnaz; Ramsden, Jeremy J.
Cell adhesion is an active process, carried out in vivo via receptor ligand-like interactions between cell surface adhesion molecules and the extracellular matrix. Initial cell surface reactions following contact may trigger multiple responses, which in tum result in either spreading or detachment of the cell. The set of adhesion and attachment molecules mediating the adhesive behaviour of stem cells and the kinetics of their interactions are as yet largely unknown. In this paper we have investigated the attachment and spreading kinetics of human embryonal carcinoma stem cells (TERA2.sp12) onto the planar Si(Ti)O2 waveguides, and covered with poly-L-lysine (PLL) or mucin, acting as substrata for the cells.
Open Access
Biological programming
(Collegium Basilea & AMSI, 2010-03) Ramsden, Jeremy J.; Bándi, Gergely
Biology offers a tremendous set of concepts that are potentially very powerfully usable for the software engineer, but they have been barely exploited hitherto. In this position paper we propose a fresh attempt to create the building blocks of a programming technology that could be as successful as life. A key guiding principle is to develop and make use of unambiguous definitions of the essential features of life.
Open Access
Chitosan–hydroxyapatite composite biomaterials made by a one step co-precipitation method: preparation, characterization and in vivo tests
(Collegium Basilea & AMSI, 2009-09) Danilchenko, S. N.; Kalinkevich, O. V.; Pogorelov, M. V.; Kalinkevich, A. N.; Sklyar, A. M.; Kalinichenko, T. G.; Ilyashenko, V. Y.; Starikov, V. V.; Bumeyster, V. I.; Sikora, V. Z.; Sukhodub, L. F.; Mamalis, A. G.; Lavrynenko, S. N.; Ramsden, Jeremy J.
A series of biocompatible chitosan/hydroxyapatite composites has been synthesized in an aqueous medium from chitosan solution and soluble precursor salts by a one-step coprecipitation method. The composite materials were produced in dense and porous variants. XRD and IR studies have shown that the apatite crystals in the composites have structural characteristics similar to those of crystals in biogenic apatite. A study of in vivo behaviour of the materials was carried out. Cylindrical rods made of the chitosan/ hydroxyapatite composite material were implanted into the tibial bones of rats. After 5, 10, 15 and 24 days of implantation, histological and histo-morphometric analyses of decalcified specimens were undertaken to evaluate their biocompatibility and the possibility to apply them in bone tissue engineering. The calcified specimens were examined by scanning electron microscopy combined with X-ray microanalysis to compare the elemental composition and morphological characteristics of the implant and the bone during integration. Porous specimens were osteoconducting and were replaced in vivo by newly formed bone tissue.
Open Access
DBT degradation enhancement by decorating Rhodococcus erythropolis IGST8 with magnetic Fe3O4 nanoparticles
(Wiley-Blackwell, 2009-04) Ansari, Farahnaz; Grigoriev, P.; Libor, Zsuzsanna; Tothill, Ibtisam E.; Ramsden, Jeremy J.
Biodesulfurization (BDS) of dibenzothiophene (DBT) was carried out by Rhodococcus erythropolis IGST8 decorated with magnetic Fe3O4 nanoparticles, synthesized in-house by a chemical method, with an average size of 45-50 nm, in order to facilitate the post-reaction separation of the bacteria from the reaction mixture. Scanning electron microscopy (SEM) showed that the magnetic nanoparticles substantially coated the surfaces of the bacteria. It was found that the decorated cells had a 56% higher DBT desulfurization activity in basic salt medium (BSM) compared to the nondecorated cells. We propose that this is due to permeabilization of the bacterial membrane, facilitating the entry and exit of reactant and product, respectively. Model experiments with black lipid membranes (BLM) demonstrated that the nanoparticles indeed enhance membrane permeability.
Open Access
The design and manufacture of biomedical surfaces
(Technische Rundschau, Hallwag Publishers; 1999, 2007-08-01T00:00:00Z) Ramsden, Jeremy J.; Allen, David M.; Stephenson, David J.; Alcock, Jeffrey R.; Peggs, G. N.; Fuller, G. D.; Goch, G.
Surfaces are the primary place of contact between a biomaterial and its host organism. Typically, prostheses have to fulfil demanding structural and mechanical requirements, yet the material best for those functions may be bio- incompatible. Surface treatment or coating provides a means to overcome that problem, which means both integration within the host physiology and stabilization with respect to corrosion and wear. The adsorption of biomacromolecules is pivotal for biocompatibility. The impossibility of keeping proteins away from most implants means that very careful consideration has to be given to this aspect, and both prevention (for bloodstream implants) and promotion (for bone replacement and repair) occur with equal importance. This paper also considers the metrology of relevant physical and chemical aspects of surfaces.
Open Access
The efficiency of chemical detectors.
(Jointly by, Collegium Basilea (Institute of Advanced Study) and Association of Modern Scientific Investigation., 2003-03) Manghani, S.; Ramsden, Jeremy J.
Chemical detectors (“sensors”) usually consist of a two-dimensional array of receptors exposed to the solution to be tested, from whose output the bulk solution concentration of the analyte of interest can be determined. Both input and output—the number of analyte particles striking the array in a given interval of time, and the number captured—are countable events. The gain is the quotient of these two numbers, and the detectivity the quotient of their fluctuations. The gain and detectivity provide a universal framework for comparing different types of sensors, and in which the desirable properties of sensors, e.g. their ability to detect very weak signals (“sensitivity”), and to detect the analyte in the presence of a large excess of other molecules (“selectivity”), can be related to various physico-chemical parameters such as the packing density and size of receptors, and their affinity for the analyte. Analyte multivalence, although formally a source of inefficiency, is very useful for making the sensor more resistant to spurious chemical noise. An important result is that chemical fog engendered by a huge excess of nonspecifically binding particles has no effect on the detectivity, provided that the nonspecific interaction is reversible.
Open Access
Ergonomic Chair Design by Fusing Qualitative and Quantitative Criteria using Interactive Genetic Algorithms
(IEEE, 2008-06-01T00:00:00Z) Brintrup, Alexandra Melike; Ramsden, Jeremy J.; Takagi, Hideyuki
This paper emphasizes the necessity of formally bringing qualitative and quantitative criteria of ergonomic design together, and provides a novel complementary design framework with this aim. Within this framework, different design criteria are viewed as optimization objectives; and design solutions are iteratively improved through the cooperative efforts of computer and user. The framework is rooted in multi-objective optimization, genetic algorithms and interactive user evaluation. Three different algorithms based on the framework are developed, and tested with an ergonomic chair design problem. The parallel and multi-objective approaches show promising results in fitness convergence, design diversity and user satisfaction metrics.
Open Access
Evaluation of sequential, multi-objective, and parallel interactive genetic algorithms for multi-objective optimization problems.
(Jointly by, Collegium Basilea (Institute of Advanced Study) and Association of Modern Scientific Investigation., 2006-09) Brintrup, Alexandra Melike; Takagi, Hideyuki; Tiwari, Ashutosh; Ramsden, Jeremy J.
We propose a sequential interactive genetic algorithm (IGA), multi-objective IGA and parallel IGA, and evaluate them with both simulated and real users. Combining human evaluation with an optimization system for engineering design enables us to embed domainspecific knowledge that is frequently hard to describe, i.e. subjective criteria, and design preferences. We introduce a new IGA technique to extend the previously introduced sequential single objective GA and multi-objective GA, viz. parallel IGA. Experimental evaluation of three algorithms with a multi-objective manufacturing plant layout design task shows that the multi-objective IGA and the parallel IGA clearly provide better results than the sequential IGA, and that the multi-objective IGA gives the most diverse results and fastest convergence to a stable set of qualitatively optimum solutions, although the parallel IGA provides the best quantitative fitness convergence.
Open Access
Films based on bacteriorhodopsin in sol-gel matrices
(International Society for Optical Engineering; 1999, 2005-09-26T00:00:00Z) Korposh, Serhiy O.; Sichka, M. Y.; Trikur, I. I.; Sharkan, Y. P.; Yang, D. H.; Lee, Seung-Woo; Ramsden, Jeremy J.
The bacteriorhodopsin film in gelatin matrixes which are used as sensitive elements of integrated optic and fibre-optic sensors of various vapor and gases components will not be able to carry out the chemical control of aqueous solutions. In the given paper the results of technological development of obtaining the bacteriorhodopsin (bR) films in a sol-gel matrix are represented. The films are obtained in a broad thickness range (from 0.5 to 20 microns) with various bR concentrations and photosensitize additives. The optimal technological conditions of obtaining of uniform films with given optical parameters are defined. The surface morphology and cross section of the obtained films was studied using an AFM and SEM. The films have a reasonable surface roughness (~ 100 nm) and a uniform distribution of the purple membrane fragments in the nanostructured sol-gel glass matrix along the films surface and thickness. The transmission spectrums have the characteristic for bR the absorption band, the value of which depends on bR concentration and technological features of the films deposition. The investigated photosensitive properties of the obtained films and influence on them of chemical components of aqueous solutions, allow recommending the thin bR films in sol-gel matrixes for creation of planar waveguides in the role of components of the chemical sensors of liquid solutions.
Open Access
For the relief of man’s estate?
(Collegium Basilea & AMSI, 2008-09) Ramsden, Jeremy J.
Editorial
Open Access
Impact factors—a critique
(Collegium Basilea & AMSI, 2009) Ramsden, Jeremy J.
The so-called impact factor (IF) started as a rather esoteric scientometric tool, itself derived from the science citation index (SCI), which originated with Eugene Garfield in the 1950s. The IF of a journal for a particular year is defined as the quotient of the number of citations received in that year by papers published in that journal in the two preceding years and the number of “citable” papers published in those two years. Had the IF remained, as might have been reasonable to expect, a specialist statistic mainly of interest to information professionals as represented by librarians and others there would be no need to expend energy on criticizing it. Unfortunately its use—or rather misuse—has vastly expanded in recent years, which makes criticism very necessary.
Open Access
The impact of Zero-valent Iron Nanoparticles upon Soil Microbial Communities is Context Dependent
(Ecomed Publishers, 2013-02-01T00:00:00Z) Pawlett, Mark; Ritz, Karl; Dorey, Robert A.; Rocks, Sophie A.; Ramsden, Jeremy J.; Harris, Jim A.
Purpose Nanosized zero valent iron (nZVI) is an effective land remediation tool, but there remains little information regarding its impact upon and interactions with the soil microbial community. Methods nZVI stabilised with sodium carboxymethyl cellulose was applied to soils of three contrasting textures and organic matter contents to determine impacts on soil microbial biomass, phenotypic (phospholipid fatty acid - PLFA), and functional (multiple substrate induced respiration - MSIR) profiles. Results The nZVI significantly reduced microbial biomass by 29% but onlywhere soil was amended with 5% straw. Effects of nZVI on MSIR profiles were only evident in the clay soils, and were independent of organic matter content. PLFA profiling indicated that the soil microbial community structure in sandy soils were apparently the most, and clay soils the least, vulnerable to nZVI suggesting a protective effect imparted by clays. Evidence of nZVI bactericidal effects on Gram negative bacteria and a potential reduction of Arbuscular Mycorrhizal fungi are presented. Conclusion Data implies that the impact of nZVI on soil microbial communities is dependent on organic matter content and soil mineral type. Thereby evaluations of nZVI toxicity on soil microbial communities should consider context. The reduction of AM fungi following nZVI application may have implications for land remediation.
Open Access
In situ observation of the evolution of porous silicon interference filter characteristics.
(Wiley-VCH Verlag GmbH & Co. KGaA, 2005-06) Volk, J.; Ferencz, K.; Ramsden, Jeremy J.; Tóth, A. L.; Bársony, I.
Porous silicon multilayer formation was observed by in situ monitoring of the reflectivity spectra in the visible range. In order to reproduce the formation process optical model simulation was carried out. For demonstration of this method a 24-layer microcavity structure was selected. Although in this low wavelengths region some absorption and scattering effects complicate the overall picture, the combined analysis throws new light upon the evolution of the porous silicon multilayer.
Open Access
The inefficiency of publicly funded research
(Association of Modern Scientific Investigation, 2010-09-30T00:00:00Z) Ramsden, Jeremy J.
Open Access
Influence of implant surface modification on integration with bone tissue
(Jointly by, Collegium Basilea (Institute of Advanced Study) and Association of Modern Scientific Investigation., 2008) Kutsevlyak, V. I.; Starikova, S. L.; Starikov, V. V.; Mamalis, A. G.; Lavrynenko, S. N.; Ramsden, Jeremy J.
Problems connected with the improvement of medical implant fixation in bone tissue are addressed by the formation of a highly developed surface and by the activation of the implant surface with an electret coating. The realization of such surface modifications is expedient for implants manufactured from tantalum or niobium or finished by coatings made from these metals, as they are chemically more inert than titanium. The techniques have been tested on animals followed by histological and mechanical analysis.
Open Access
Integrated optical devices using bacteriorhodopsin as active nonlinear optical material
(2006-08-15T00:00:00Z) Dér, A.; Fábián, L.; Valkai, S.; Wolff, E.; Ramsden, Jeremy J.; Ormos, P.; Norwood, R. A.
Coupling of optical data-processing devices with microelectronics, telecocommunication and sensory functions, is among the biggest challenges in molecular electronics. Intensive research is going on to find suitable nonlinear optical materials that could meet the demanding requirements of optoelectronic applications, especially regarding high sensitivity and stability. In addition to inorganic and organic crystals, biological molecules have also been considered for use in integrated optics, among which the bacterial chromoprotein, bacteriorhodopsin (bR) generated the most interest. bR undergoes enormous absorption and concomitant refractive index changes upon initiation of a cyclic series of photoreactions by a burst of actinic light. This effect can be exploited to create highly versatile all-optical logical elements. We demonstrate the potential of this approach by investigating the static and dynamic response of several basic elements of integrated optical devices. Our results show that, due to its relatively high refractive index changes, bR can be used as an active nonlinear optical material to produce a variety of integrated optical switching and modulation effects.
Open Access
Integrated qualitativeness in design by multi-objective optimization and interactive evolutionary computation.
(2005-09-01T00:00:00Z) Brintrup, Alexandra Melike; Ramsden, Jeremy J.; Tiwari, Ashutosh
Abstract- The concept of qualitativeness in design is an important one, and needs to be incorporated in the optimization process for a number of reasons outlined in this paper. Interactive Evolutionary Computation and Fuzzy Systems are two of the widely used approaches for handling qualitativeness in design optimization. This paper classifies the types of qualitativeness observed in design optimization, makes the case for their necessity, and proposes a novel framework for handling them, combining the two approaches in an evolutionary multi-objective optimization platform. Two components of the framework are tested using the floor-planning problem, and observations are reported. Future work is defined onthe development of the framework.
Open Access
Inversion of values?
(Collegium Basilea & AMSI, 2005-09) Ramsden, Jeremy J.
Editorial
Open Access
Lag phases in the adsorption of lysozyme to Si(Ti)O2 surfaces in the presence of sodium thiocyanate. Part I. Phenomenology.
(Royal Society of Chemistry, 1999) Ball, Vincent; Lustig, Ariel; Ramsden, Jeremy J.
The adsorption kinetics of hen egg white lysozyme (HEWL) in the presence of NaSCN at pH 7.4 onto Si0.8Ti0.2O2 surfaces were measured by means of time-resolved optical waveguide lightmode spectroscopy (OWLS). The adsorption kinetics were characterized by the presence of a lag phase whose duration decreased with increasing lysozyme bulk concentration. This lag phase was followed by rapid growth of the interfacial protein film which ceased at a surface coverage close to that predicted for a monolayer. At bulk concentrations lower than about 50 µg cm-3, the maximum rate of adsorption was equal to the rate predicted for a transport-controlled process from the solution to the surface and at higher bulk concentrations such lag phases were no longer observed. Storage of lysozyme solution prior to adsorption reduced the duration of the lag phase, but analytical ultracentrifugation measurements showed the absence of significant aggregation even at bulk concentrations of 103 µg cm-3. These features are consistent with an adsorption process requiring the adsorption of a small critical nucleus preformed in solution followed by the completion of the adlayer by a mechanism akin to crystal growth. The size of this critical nucleus was estimated to be of the order of only a few lysozyme molecules.