Objective To examine the segmental bone defects healing by ? TCP/rhBMP 2 composites with different degradation rate and discuss the relationship between osteogenesis and degradation of ? TCP in vivo. Methods Three kinds of ? tricalcium phosphate(? TCP) with different degradation rate (? TCP1-3) were prepared by means of different techniques. ? TCP/rhBMP 2 composites with different degradation rate(? TCP1/rhBMP 2 and ? TCP2/rhBMP 2)were obtained by combining ? TCP1, ? TCP2 with recombinant human bone morphogenetic protein 2(rhBMP 2), respectively. ? TCP1/rhBMP 2, ? TCP2/rhBMP 2, ? TCP1, ? TCP2 and ? TCP3 were used to repair 15 mm radial segmental defects in 81 Chinese rabbits. When the samples were harvested in 4, 8, 16 and 24 weeks after surgery, a series of examination were carried out, including the roentgenographical, histomorphological, biomechanical and computerized graphical analysis, energy dispersion analysis X ray (EDAX), and measurements of inorganic contents. Results Roentgenographically and histologically, all of the defects that had been treated with implants exhibited new bone formation, increasing with time. The quantity and rate of new bone formation in ? TCP1/rhBMP 2 group and ? TCP2/rhBMP 2 group were higher than those in group of ? TCP alone. The ability of new bone formation in ? TCP1/rhBMP 2 group was strongest. At 24 weeks the defects in ? TCP1/rhBMP 2 group were bridged with the appearance of marrow cavities, the inorganic contents and ratio of calcium to phosphate and biomechanical property in implants approached to those of normal bone. Although degradation occurred to some extent in ? TCP alone the degradation were faster in ? TCP/rhBMP 2 composites. At 24 weeks the degradation rate in ? TCP1/rhBMP 2 group and ? TCP2/rhBMP 2 group were 97.4%and 73.4%, respectively. The defects in blank controls were repaired only by fibrous tissue at 24 weeks. Conclusion ? TCP/rhBMP 2 composites with different degradation rate could repair segmental bone defects, and osteogenesis could accelerate the degradation of ? TCP in vivo.

The methods, present research situation, existing problems, and application foreground of multidimensional reconstruction of ultras onic heart images are discussed in the present paper. According to the procedure of multidimensional reconstruction of ultrasonic heart images, the discussions are presented in respect toimage acquisition, processing, and display. Based on the present situation and existing problems, the future development and applica tion foreground are proposed.

Several kinds of filters for medical ultrasonic images, suchas multidimensional filter, adaptive weighted filter (for example, adaptive weighted median filter), adaptive window selecting filter (for example , homogeneous region growing mean filter and adaptive speckle suppression filter ) and two-step filter, are introduced. The existing problems and the progress trend are also discussed. Some application instances for medical ultrasonic images of the filters discussed and the performance of the filters presented are based on the present authors' practice.

Contour detection is one of the most difficult problems in the multi-dimensional reconstruction of echocardiographic images. A method based on active contour model is presented in the present paper to solve this problem. First, according to the characteristic of the ultrasonic medical images, an adaptive weighted median filter is used to suppress speckle noise and an adaptive threshold value is selected to get binary image. Then, mathematical morphological treatment is utilized to get the initial contour. At last, active contour model is employed to revise the initial contour and get the accurate final contour. Experiments with real and interpolated ultrasonic images are presented. The results show the effectiveness of this method. This method has practical use in the multi-dimensional reconstruction of ultrasonic medical images.

During the preparation of functional gradient materials (FGM) with plasma immersion ion implantation-ion beam enhanced deposition (PIII-IBED), the combination strength between the coating and the substrate would be greatly affected by the implantation dose and the distribution of implanted ions in substrate. According to the requirements of FGM, an idea of multi grades energy implantation had been suggested, with which the Gauss peak could be moved toward the surface, and the concentration of implanted ions could be maximized at the surface. In this study, the distribution of carbon ions implanted into titanic alloy substrate have been simulated theoretically, and the tentative idea have been confirmed experimentally.
Alloys ; Carbon ; Coated Materials, Biocompatible ; chemical synthesis ; Computer Simulation ; Heart Valve Prosthesis ; Titanium

Objective To improve the precision of the traditional segmentation of echocardiogram, by suppressing the influence from inherent speckle noises in medical ultrasonic images. Method An automatic segmentation method based on reconstructed morphology was proposed in this paper. First, the opening and closing operations by reconstruction were imposed to the ultrasonic image. Second, the top-hat operation was used to extract the bright and/or dark features and to find out the boundaries corresponding to these features, whereby implemented the automatic segmentation. Result The segmented echocardiogram had less artificial boundaries resulted from speckle noise, and could accurately be extracted the artery and ventricle. Conclusion The presented method can detect both dark and bright objects accurately, and the boundary has a fine continuity. In addition, the algorithm is also applicable to the extraction of sole bright/dark features, accordingly to reduce the complexity and time needed and to improve the accuracy.

Studies on bioactive glass and glass-ceramic are important research high-lights in the field of biomedical materials. Due to their bioactivity, these materials can form a tight chemical bond with the living bone, when implanted. As a preeminent kind of these materials, A-W(Apatite/Wollastonite) bioactive glass ceramic has not only the excellent bioactivity and biocompatibility, but also the eminent mechanical properties, so it has been largely applied and developed in clinical practice. The development, preparation, properties, applications and the mechanism of its bond with bone are introduced in this paper. We will also put forward the prospect of the research and development of A-W bioactive glass ceramic.
Apatites ; chemistry ; Bone Substitutes ; chemistry ; Calcium Compounds ; chemistry ; Ceramics ; chemistry ; Mechanics ; Research ; Silicates ; chemistry ; Surface Properties

A promising alternative to supply bone substitutes is to develop living tissue substitutes based on biodegradable materials, which is called bone tissue engineering. One of the research high-lights of bone tissue engineering is to design and manufacture scaffolds for cell attaching, migrating, and proliferating. A process which consists of a solvent casting stage, a compression molding stage and a leaching stage has been used to fabricate macroporous composites of poly(l-lactic acid)(PLLA) and β-tricalcium phosphate (β-TCP). The effects of the weight fraction of porogen-NaCl, of the weight ratio of PLLA to β-TCP and of the diameters of β-TCP on the porosities, the average pore diameters and the compressive yield strength and compressive modulus have been studied. The results showed that the porosities and the average pore diameters increased and the compressive yield strength and modulus decreased when the weight fraction went from 50% to 90%. The compressive yield strength and compressive modulus could be improved by changing the weight ratio of PLLA to β-TCP and the diameters of β-TCP in low-porosity composites (lower than 70%). But high-porosity composites (90%) were not reinforced by changing the weight ratio.

The correlations between surface energy parameters and carbon phase components in six diamond like carbon film (DLC) samples made in different ways and processing conditions were further investigated using the analysis of T-type correlation degree in the Grey system theory based on our earlier studies such as the determination of carbon phase and surface energy parameters, the analyses of carbon phase components, surface energy parameters and adhesive characteristic of platelets for DLC. The results showed: (1) as a whole critical surface tension has the closest relation with carbon phase components, chromatic dispersion branch of surface tension takes the second place, but for the other four parameters, the correlation is weak; (2) DLC phase has larger negative correlation (degrees -0.57, -0.33) with critical surface tension and chromatic dispersion branch of surface tension, while its correlation degrees with the other four parameters related to polarity are all positive values smaller than 0.20; (3) C-H phase and C-O phase have larger positive correlation (degrees 0.48, 0.25) with critical surface tension. We have come to three conclusions (1) DLC phase plays a dominant part in hemocompatibilioty of DLC by powerfully decreasing humidification and limitedly increasing polarity; (2) the energy mechanism of platelet deformation enhanced by C-H phase and C-O phase involves increasing the critical surface tension of DLC; (3) the hemocompatibility of DLC can be evaluated by using the critical surface tension as index and using the content of DLC phase and additional content limitation of C-H phase and C-O phase as standard. This study has provided a theoretical basis for evaluating the hemocompatibility of DLC based on surface properties.
Biocompatible Materials ; chemistry ; Carbon ; chemistry ; Diamond ; chemistry ; Humans ; Male ; Materials Testing ; Membranes, Artificial ; Models, Biological ; Platelet Adhesiveness ; drug effects ; Surface Properties

In this study, the diamond like carbon (DLC) samples made from different processes and processing conditions, were subjected to the test of platelet adhesion. The surface energy parameters such as surface tension, critical surface tension, interface tension, adhesive power, and polar branch and chromatic dispersion branch of surface tension based on determining balanced contact angle of ethanol, water and different ratios of ethanol/water solution on surfaces of the samples were calculated, respectively. Then the effects of these parameters on the amounts and deformation index of the platelets adhering to the samples were assessed by analyzing the T-type correlation degree in the Grey system. The results showed: (1) all degrees of correlation between surface energy parameters and adhesion amounts of platelet are positive, but for deformation index, the correlation degrees are negative except for critical surface tension; (2) the adhesion amounts of platelet increase with the rising polar branch of surface tension, while the deformation index increases with rising chromatic dispersion branch of surface tension; (3) Both adhesion amounts and deformation index of platelet are positively correlated with critical surface tension to a higher degrees; (4) the effects of polar branch of surface tension on adhesion amounts and deformation index of platelet keep pace with the surface tension, interface tension and adhesive power. Thus two important conclusions have been obtained: (1) the adhesive characteristic of platelets to the surface of DLC is closely related with the surface energy of DLC; the hemocompatibility of DLC is decided by the balance between the polarity of DLC surface and the limited humidifying water on the surface; there is a blood compatible range delimited by critical surface tension; (2) adhesion and deformation of platelets on surface of DLC have different energy mechanism: polar surface is advantageous to the adhesion, while the deformation is achieved with the aid of chromatic dispersion action stem from the surface.
Biocompatible Materials ; chemistry ; Carbon ; chemistry ; Diamond ; chemistry ; Humans ; Materials Testing ; Platelet Adhesiveness ; Surface Properties