Bio-Medical Materials and Engineering - Volume 2, issue 3

Authors: Warren, Lawrence D. | Chowdhary, Pratap Rai

Article Type: Research Article

Abstract: The electrochemical properties of various porous metal coatings used in reconstructive orthopedic prosthetics were examined. Potentiodynamic corrosion testing was used to evaluate the behavior of the following porous metals; CSTi™ on Cast CoCr, CSTi™ on Ti-6Al-4V, CoCr beads on Cast CoCr, CoCr beads on Ti-6Al-4V, CP Ti beads on Cast CoCr, and CP Ti beads on Ti-6Al-4V. Analysis of the resultant corrosion scans showed that these materials behave similarly to one another. No corrosion-related anomalies were noted.

Keywords: orthopedics, porous metals, electrochemical properties, potentiodynamic behavior, corrosion testing

DOI: 10.3233/BME-1992-2301

Citation: Bio-Medical Materials and Engineering, vol. 2, no. 3, pp. 107-113, 1992

Authors: Nordström, E. G. | Niemi, L. | Miettinen, J.

Article Type: Research Article

Abstract: Slip cast conical implants of HA, carbonate-HA, calcium orthophosphate/hydroxyapatite and hydroxyapatite/calcium pyrophosphate/calcium orthophosphate with weight ratios 75/25 and 50/30/20 were implanted in rabbit tibia. The bone-implant interfaces were evaluated histologically, by means of SEM/EDX analysis and by push-out test. Thirty-six implanted samples were investigated after 2, 8, and 24 weeks. The triphasic calcium phospate showed a moderate disintegration. This material showed 2 weeks after implantation a bonding between new bone and implant could be seen in parts of the operation site by SEM. Eight weeks after implantation an intimate relationship between the bone tissue and all specimens of each material …was found. After 24 weeks the Ca/P ratio in the bone had reached the Ca/P ratio of mature bone determined by SEM/EDX analysis. Show more

Keywords: calcium phosphates, hydroxyapatite, implants

DOI: 10.3233/BME-1992-2302

Citation: Bio-Medical Materials and Engineering, vol. 2, no. 3, pp. 115-121, 1992

Authors: Shinde, B. G. | Nithianandam, V. S. | Kaleem, K. | Erhan, S.

Article Type: Research Article

Abstract: A method was developed to prepare a simple, flexibilized gelatin film-based artificial skin model. The films are tough, adhere to open wounds spontaneously, are permeable to body fluids, and can release incorporated bioactive compounds over 4–5 days.

Keywords: artificial skin, flexibilized gelatin film, model

DOI: 10.3233/BME-1992-2303

Citation: Bio-Medical Materials and Engineering, vol. 2, no. 3, pp. 123-126, 1992

Authors: Shinde, B. G. | Erhan, S.

Article Type: Research Article

Abstract: Any delivery system for bioactive molecules should have the ability to release the compound in question in a reproducible and predictable way over a certain period. For artificial skin models that are designed to enhance healing by the use of growth factors, this requirement poses another problem: the design of a delivery method that can provide a realistic assessment of the release kinetics. This means that the design should “mimic” conditions encountered in an open wound, i.e., only a certain part of the film can face the wound, from which it can absorb wound fluid that will dissolve the incorporated …bioactive molecule and bring it to the open wound. Such a system has been developed and the release of 125 I-labelled insulin, incorporated into flexibilized gelatin films, has been determined. The details of this study follow. Show more

Keywords: kinetics, release, gelatin film, artificial skin

DOI: 10.3233/BME-1992-2304

Citation: Bio-Medical Materials and Engineering, vol. 2, no. 3, pp. 127-131, 1992

Authors: Wang, B. C. | Wang, G. R. | Yan, D. H. | Liu, Y. P.

Article Type: Research Article

Abstract: Hepatic tissue is an important internal organ for life. In this paper, we combined the moire method (an optical method) and indentation technique to investigate biomechanical response of hepatic tissue. To examine this measuring technique, we first measured the biomechanical properties of the block of pig's hepatic tissue using this method. The experimental result indicated that the pig's hepatic tissue was obviously a viscoelastic material. We closely analyzed the change of curves for force relaxation, creep, and nonlinear defonnation of the block of pig's liver. Meanwhile, we also compared the changes in the biomechanical parameters of nonnal and cirrhosis hepatic …tissue of humans. Show more

Keywords: hepatic tissue, force-relaxation, creep, nondeformation, moire method, indentation, technique

DOI: 10.3233/BME-1992-2305

Citation: Bio-Medical Materials and Engineering, vol. 2, no. 3, pp. 133-138, 1992

Authors: Nakamura, Takao | Hayashi, Kozaburo | Seki, Junji | Fukuda, Sachito | Noda, Hiroyuki | Nakatani, Takeshi | Takano, Hisateru | Akutsu, Tetsuzo

Article Type: Research Article

Abstract: Pneumatically driven, diaphragm type left ventricular assist devices (LVADs) were implanted into 2 goats with normal hearts for approximately 1 month to study the effects of long-term pumping of LVAD on the cardiac mechanics. One sham-operated goat was used to obtain control data. Diameters and myocardial segment lengths of the left ventricle were measured with an ultrasonic displacement meter to calculate the bulk mechanical work (BMW) and regional myocardial mechanical work (RMW), respectively. The LVAD was pumped in the 2:1 drive mode (one counterpulsated pumping in every two cardiac cycles), and was temporarily driven in the 1:1 mode (one pumping …in every cardiac cycle) or stopped to obtain the data under these conditions. During the second half of the post-operative period while the animal condition was stable, the BMW in the 2:1 and 1:1 modes were approximately 59% and 72% of that observed under the temporary pump-off condition (0.22 W/(lOO g)), respectively. The RMW in the 2:1 and 1:1 modes were 69% and 74% of that obtained during pump-off (6.2 mW/cm3 ), respectively. The myocyte diameter in the subendocardial layer was reduced by unloading effect of 1-month pumping, whereas those in middle and subepicardial layer showed little change. Show more

Keywords: bulk mechanical work, chronic experiment, left ventricular assist device, regional mechanical work, ultrasonic displacement meter

DOI: 10.3233/BME-1992-2306

Citation: Bio-Medical Materials and Engineering, vol. 2, no. 3, pp. 139-153, 1992

Authors: Ursino, M. | Artioli, E.

Article Type: Research Article

Abstract: The values of the propagation coefficient measured on a silicon rubber tube in the frequency range 1–15 Hz were compared, using four different equations. The first formula is based on three simultaneous pressure measurements performed at equidistant points; the remaining three equations are original, and make use of only two of the three pressure measurements together with a no-flow condition at the terminal tube section. The results of our trials demonstrate that the experimental phase velocity, obtained with all equations, settles at a value about 25% in excess of the theoretical one computed with a classic linear mathematical model. …This result may be explained by an increase in the dynamical Young modulus with respect to that measured in static conditions. However, the three-point method introduces great errors in the results in the frequency range 11–14 Hz where the spectrum of the second signal becomes minimum. In all cases, the experimental value of attenuation per wavelength at mid-high frequencies is greater than the theoretical one valid for a purely elastic tube. The attenuation values obtained with the two-point method can be explained by introducing a small contribution of wall viscoelasticity (2–3°) into the linear model. Attenuation per wavelength computed with the three-point method turns out about threefold that computed with each of the two-point formulas. This result supports the idea that the accuracy of the three-point method may be insufficient to achieve correct estimation of wave attenuation, especially when the distance between transducers is small compared to wavelength. Show more

Keywords: attenuation per wavelength, phase velocity, viscoelastic tubes, wave propagation

DOI: 10.3233/BME-1992-2307

Citation: Bio-Medical Materials and Engineering, vol. 2, no. 3, pp. 155-169, 1992

Article Type: Other

DOI: 10.3233/BME-1992-2308

Citation: Bio-Medical Materials and Engineering, vol. 2, no. 3, pp. 171-171, 1992