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  • 11
    Electronic Resource
    Electronic Resource
    Scanning electron microscopy of the bone-bioactive implant interface (1997)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 36 (1997), S. 429-440 
    Details
    ISSN: 0021-9304
    Keywords: bone ; interface ; cement line ; bioactive glass ; AW glass ceramic ; hydroxyapatite ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Rods of three bioactive materials, apatite/wollastonite glass ceramic (AW-GC), bioactive glass (BG), and dense slip-cast hydroxyapatite (HA), were implanted in the femora of 23 Wistar rats for periods of 1-4 weeks. The samples were harvested following vascular perfusion fixation and the femora freeze-fractured for scanning electron microscopy to expose the bone/implant interface. The focus of our observations was when new bone was forming on the implant surfaces irrespective of the implantation period. Scanning microscopy of the hydroxyapatite rods demonstrated that in areas where bone bonding had occurred, the implant surface was composed of globular accretions which fused to form a cement-like matrix to which collagen fibers were attached. Dissolution of individual grains of the implant surface created a roughened surface topography. Such features were not found in the transcortical portions of these implants. Similar globular accretions were also found on the surfaces of bulk AW-GC, although bone apposition was not disrupted by the critical point-drying procedure, and thus the interface was more difficult to image. Nevertheless, the collagen of the bony compartment interdigitated with an interfacial layer which was morphologically similar to that found on HA. The most surface reactive material, BG, demonstrated an interfacial structure where the surface reactive calcium phosphate layer was clearly distinguished from the underlying bulk implant material. However, this layer was separated from the overlying collagen-containing bony compartment by a second, thinner, calcified layer which corresponded to the cement line matrix into which the collagen fibers were inserted. Our results show that the new bone interface formed with these three bioactive materials is morphologically comparable to that of cement lines found naturally in bone-remodeling sites, and that this interfacial layer is formed on the chemically active surface of the biomaterial. The degree to which the cement line matrix interdigitated with the implant was a product of the reactivity of the implant surface. © 1997 John Wiley & Sons, Inc. J Biomed Mater Res, 36, 429-440, 1997.
    Additional Material: 8 Ill.
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  • 12
    Electronic Resource
    Electronic Resource
    Attachment, morphology, and protein expression of rat marrow stromal cells cultured on charged substrate surfaces (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 42 (1998), S. 117-127 
    Details
    ISSN: 0021-9304
    Keywords: electrical stimulation ; cell attachment ; alkaline phosphatase ; osteopontin ; protein adsorption ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Although surface charge has been shown to affect the adhesion and morphology of a variety of cell types, the interactions of bone marrow stromal cells with charged surfaces still remain unclear. A novel electrical stimulation system was used to investigate the interactions between rat bone marrow stromal cells and charged substrates in this study. A conductive and transparent indium tin oxide (ITO) coating was used as an electret substrate. Rat marrow stromal cells were cultured on positive, negative, and uncharged ITO surfaces. Cell attachment, morphology, alkaline phosphatase activity, and expression of osteopontin and collagen type III were assessed using histochemical staining, immunolabeling, and fluorescence microscopy. Voltages of 0.7, 0.8, 0.9, and 1.0 V applied to the substrates created surface potentials but were insufficient to decompose the media. On positively charged ITO, cell attachment was enhanced in serum-supplemented and serum-free media. Furthermore, decreases in cell spreading, alkaline phosphatase activity, and osteopontin were observed in cells grown on the positively charged ITO. These data indicate that positively charged surfaces enhance cell attachment but suppress cell spreading and differentiation of rat marrow stromal cells. © 1998 John Wiley & Sons, Inc. J. Biomed Mater Res, 42, 117-127, 1998.
    Additional Material: 12 Ill.
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  • 13
    Electronic Resource
    Electronic Resource
    Biospecific adsorption of lysozyme onto monoclonal antibody ligand immobilized on nonporous silica particles (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 34 (1989), S. 467-477 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It is very important to understand the equilibrium and dynamic characteristics of biospecific adsorption (affinity chromatography) for both scientific and application purposes. Experimental equilibrium and dynamic column data are presented on the adsorption of lysozyme onto antibody immobilized on nonporous silica particles. The Langmuir model is found to represent the equilibrium experimental data satisfactorily, and the equilibrium association constants and heats of adsorption have been estimated for two systems with different ligand densities. The effects of nonspecific interactions are more pronounced in the system with low-density ligand. The dynamic interaction kinetic parameters are estimated by matching the predictions of a fixed-bed model with the experimental breakthrough curves. The agreement between theory and experiment is good for the initial phases of breakthrough, where the mechanism of biospecific adsorption is dominant. In the later phase (saturation neighborhood) of breakthrough, the effects of nonspecific interactions appear to be greater in the low-density ligand system. The kinetics of the nonspecific interactions were estimated from the data of the later phase of breakthrough and were found to be considerably slower than those attributed to biospecific adsorption.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260340406
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  • 14
    Electronic Resource
    Electronic Resource
    The bone-titanium interface in vitro (1990)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 24 (1990), S. 1289-1306 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Commercially pure 5-mm-diameter titanium (cpTi) discs received droplet inoculations of cells derived from rat bone marrow and were maintained in supplemented culture medium for 2-3 weeks. The cells and extracellular matrix (ECM) were processed for observation by light (LM), scanning (SEM), and transmission electron (TEM) microscopy. The latter was achieved by freeze-fracturing the solid metal from the resin-embedded tissue using a method which preserved the interface. Surface staining of whole discs revealed cells separated from the metal substratum by areas of ECM which stained positively using von Kossa's method to identify mineralization. At SEM, the ECM comprised dense interwoven collagen fiber networks which were partially obscured by globular masses (GMs). Individual GMs were associated with collagen fibers, especially at fiber intersections. EDAX line scan analysis confirmed the presence of Ca and P in these areas which were assumed to be spheritic foci of calcification since the Ca and P peaks diminished in areas which demonstrated only collagen fibers or the underlying cpTi. TEM examination confirmed the presence of globular mineralization and also revealed the presence of an interfacial zone between the metal substratum and the mineralized ECM elaborated by osteoblasts during the culture period. The interfacial zone comprised two layers, a bonding zone containing few collagen fragments and a ruthenium red positive layer containing more densely packed collagen fibers. We believe that this is the first report of both the formation of bonelike tissue on solid titanium substrata in vitro and demonstration of an interface which bears close morphological similarities to that known to develop in vivo.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820241003
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  • 15
    Electronic Resource
    Electronic Resource
    Guided bone tissue elaboration by osteogenic cells in vitro (1993)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 27 (1993), S. 429-431 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Primary rat bone marrow cells were cultured for 2 weeks in polystyrene dishes whose surfaces had been roughened using 600- or 320-grit silicon carbide paper. Eight samples were prepared of each of the three groups of dishes, to include a nontreated control suface. Following the culture period, the dishes were stained by von Kossa's method. The distribution of bone formed during the culture period was examined by light microscopy and the area of bone formed quantified. Results demonstrated that both the amount and spatial distribution of bone were influenced by the roughness of the underlying substratum. Differences between the smooth and roughened surfaces were statistically different at P 〈 .05. © 1993 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820270403
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  • 16
    Electronic Resource
    Electronic Resource
    Nitric acid passivation of Ti6A14V reduces thickness of surface oxide layer and increases trace element release (1995)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 29 (1995), S. 279-290 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Passivation of Ti6Al4V and cpTi implants using methods based on the ASTM-F86 nitric acid protocol are used with the intention of reducing their surface reactivity, and consequently the corrosion potential, in the highly corrosive biologic milieu. The ASTM-F86 passivation protocol was originally developed for surgical implants made of stainless steel and chrome cobalt alloy. Using X-ray photoelectron spectroscopy (XPS) to examine the effect of nitric acid passivation on the surface oxide layer of mill-annealed Ti6Al4V and cpTi, we have found that such treatment actually reduced the oxide thickness on the alloy while having no significant effect on the pure metal. These results correlated with observations obtained using graphite furnace atomic absorption spectrophotometry (GFAAS) to detect trace element release from solid, mill-annealed, Ti6Al4V and cpTi into serum-containing culture medium. We detected significantly greater levels of Ti, Al, and V in the presence of passivated compared to nonpassivated Ti6Al4V. In contrast, nitric acid passivation did not influence Ti release from mill-annealed Ti-based metals, would indicate that re-examination of ASTM-F86-based passivation protocols with respect to Ti6Al4V should be considered in view of the widespread use of this alloy for biomedical devices. © 1995 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820290302
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  • 17
    Electronic Resource
    Electronic Resource
    Effect of analytical method on thickness measurements of thin oxide films (1988)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 11 (1988), S. 441-446 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The thickness of thin natural oxide films formed on silicon, nickel, aluminium, iron, tantalum and zirconium has been measured using nuclear reaction analysis (NRA) and Auger electron spectroscopy (AES) in combination with ion beam sputtering. It is shown that ion beam effects severely limit the use of AES and ion beam sputtering in measuring thin oxide thicknesses. Relatively non-destructive techniques such as NRA or angle-resolved x-ray photoelectron spectroscopy (XPS) provide more reliable information.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740110806
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  • 18
    Electronic Resource
    Electronic Resource
    Fourier transform Raman and fourier transform ir spectroscopic investigation of pyrazine adsorbed by sepiolite and bentonite from anatolia (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 26 (1995), S. 883-888 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The adsorption of pyrazine by two different Anatolian sepiolites and by natural and ion-exchanged (Fe, Co, Cu and Sn) bentonites was investigated by vibrational spectroscopy. The spectroscopic results indicate that the pyrazine molecules adsorbed on sepiolite and bentonites are coordinated to either surface hydroxyls by H-bonding interaction (in the case of sepiolite) or to exchangeable cations (in the case of bentonites) through both nitrogen lone pairs as bidentate ligands. X-ray diffraction patterns of the clays were also recorded and the basal spacings of pyrazine-treated natural and ion-exchanged bentonites were found to be around 14.7 Å. The results suggest that pyrazine molecules intercalate the interlayers of bentonite with a monolayer arrangement.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250260840
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  • 19
    Electronic Resource
    Electronic Resource
    Solid state vibrational spectroscopy. 9For paper 8 in this series see K. D. Cleaver and J. E. D. Davies, J. Raman. Spectrosc. 9, 376 (1980). - A kinetic study, using Raman spectroscopy, of the solid state thermal decompositions of alkali metal peroxydisulphatesPresented at the Sixth International Conference on Raman Spectroscopy, 4-9 September 1978, Bangalore. India. (1980)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 9 (1980), S. 381-383 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetic behaviour of the solid state thermal decomposition of peroxydisulphate to pyrosulphate, M2[S2O8] → M2[S2O7], M = Na, K, Rb, Cs, has been studied by following the temporal decrease in the intensity of the Raman band arising from the vs(SO3) mode of [S2O8]2-. The data are best analysed using a conventional kinetic approach rather than the Avrami-Erofeev treatment normally applied to solid state reactions. Although the salts display different kinetic orders, 1.5, 2.0, 1.0 and 1.0 for the Na, K, Rb and Cs salts respectively, the lack of crystallographic data does not allow us to rationalize these differences.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250090608
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  • 20
    Electronic Resource
    Electronic Resource
    Characterization of interfaces in ceramic composites by SIMS, AES and EPMA (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 18 (1992), S. 23-31 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Fracture surfaces and polished cross-sections of aligned SiC fibre-cordierite matrix composites have been studies using SIMS, AES and electron probe x-ray microanalysis (EPMA). It has been shown that, during fabrication, interface reactions resulting in penetration of the fibres by matrix cations take place. Titanium diffusion out from the fibres together with segregation of matrix elements to the interface is also observed. A correlation is found between interface composition and mechanical properties of the composites. The relative merits of SIMS, AES and EPMA in the determination of the nature of the fibre-matrix interface are discussed. SIMS using a microfocused Ga ion beam is shown to be a powerful new tool in the investigation of interfaces.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740180105
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