Papers by Keyword: Medical

Abstract: Electron beam welding technology is a mature special welding technology. The advantage of electron beam welding like these: high power density, high ratio of depth-to-width, high-quality welds. Electron beam welding equipment has been independently developed by tracking and bringing in. Electron beam welding technology has a wide range of applications in the aerospace, automotive, medical and other branches of industry, the field of applications is also expanding with the improved welding equipment. According to the demand of research and market, Electron beam welding technology will move toward the direction of universal, integrated, information-oriented in the future.

Abstract: In this study, the influence of employing three different sodium hydroxide (NaOH) pretreatment concentration (1, 3 and 5M) and two cleaning methods (Ultrasonic or Rinse) used in rapid biomimetic coating process on phase composition, function groups, thickness, amount and microstructure of the resulted coating was carried out. Regardless of process parameters, x-ray diffraction and Fourier transform infrared spectroscopy revealed that the all coating mainly comprised octacalcium phosphate and hydroxyapatite as main phases while the microstructure similarly consisted of sharp and interconnected plate-like calcium phosphate (CaP) crystals vertically grown on the surface of titanium. However, the change in sodium hydroxide concentration in pretreatment step and cleaning method influenced the weight change after pretreatment, coating continuity and uniformity, but not the weight change after coating. This could be related to amount of the amorphous alkali gel layer formed during pretreatment step which influenced the rate of coating formation in rapid biomimetic coating process.

Abstract: The study of the characteristics of WBAN channel model is crucial, due to the fact that it is an important step to design wireless body area network (WBAN). WBAN channel models are so different from the traditional mobile channel models and there are few publications on them. In this paper, we studied the statistic characteristics of the WBAN channel based on the IEEE 802.15.6 models. We focus on body surface to body surface circumstance, simulated the path loss models on 400, 600 and 800MHz and studied the statistic characteristics of the path loss models. Finally, we used the Guass model to fit the statistic results of the path loss and obtained coefficients of Gauss model .

Abstract: In this paper, several nonwoven and woven clothing are be selected for tested their protective, strength and comfortable. Through analysis their properties, the result can be seen that the nonwoven fabrics have better protective properties than woven fabrics, especially PVA nonwoven through water resistance finish. So, varies nonwoven clothing is used in hospital and family protective daily.

Abstract: In this study, four types of PEG-PPG-PEG copolymers solids and pastes having different molecular mass (M_w~5800, 8400, 12000 and 14600) were selected and mixed at various compositions ranging from 40 to 60 % by weight. The textures and handling characteristics of the prepared samples were evaluated in comparison to that of the commercial non-resorbable bone wax. Thermal and mechanical properties of the blends were determined by a differential scanning calorimeter and a universal testing machine respectively. It was found that the combination of solid (M_w~8400) and paste-like (M_w~12000) copolymers at the ratio of 40:60 gave the closest smooth texture with good smearability and had similar melting temperature to the commercial bone wax, but having slightly lower compressive stiffness. Preliminary cytotoxicity of the selected formulations against osteoblasts revealed that the cell viability was greater than 70 % indicating that the prepared samples did not show any cytotoxic potential.

Abstract: Recently, porous hydroxyapatite was fabricated by three dimensional printing (3DP) in coupled with low temperature phosphorization to yield nanosized and low crystalline structure. However, brittleness was an intrinsic drawback for some foreseen applications. Polymer infiltration aiming to improve the toughness and mechanical integrity was thus carried out using biodegradable poly(ε-caprolactone) (PCL) as an infiltrant since it has shown good biocompatibility together with a high elongation and energy to failure as compared to other medical polymers. Three routes of infiltration were performed including melt infiltration of low molecular weight PCL (Mw ˜ 10,000), solution infiltration by 10 % high molecular weight PCL (Mw ˜ 80,000) and the combination of both melt and solution infiltration of low and high molecular weight PCL. The combination of low and high MW infiltration yielded the greatest increase in the mechanical properties and followed by the melt infiltration of low molecular weight PCL while the use of high MW infiltration yielded limited enhancement. After immersing in simulated body fluid (SBF), no significant changes in flexural properties were seen for both hydroxyapatite and high molecular weight infiltrated sample. However, flexural strength and strain at break of low molecular weight infiltrated sample largely dropped after 7 days of immersion to be closed to those of hydroxyapatite and high molecular weight infiltrated sample. The flexural properties of high-low infiltrated sample also decreased after immersion, but to a less degree and still maintained the greatest values amongst all samples. This could be associated to the difference in degradation of different molecular weight of PCL and the content of polymer infiltration induced by different infiltration routes. Calcium and phosphorus ions in the SBF were quantified and observed to be consumed continuously during immersion for all samples. Newly formed apatite crystals were observed to form on the surface of the infiltrated composites signifying that infiltration did not hinder the bioactivity of the composites.

Abstract: In textile techniques, woven, knitted, non-woven and braiding techniques all can be used to weave tubular fabrics as intraluminal stents. The radial force is the most basic mechanical property of intraluminal stent. In this study, the influence of braiding parameters such as braided materials, diameter of stents and gear ratio on the radial compressive property of braided stents were studied.

Abstract: Development of an appropriate propagation channel model is an important step to design wireless body area network (WBAN). Because the human body has different body shapes (male, female and child), different tissues with different permittivity and conductivity (even the same person at the different age), and limbs positions and postures are changing all the time, this made the in-body channel modelling extremely difficult, if not impossible. There are few publications on implant communication channel models compared to wearable WBAN. In this paper, we present a literature survey on radio channel modelling for WBAN, especially the IEEE 802.15.6 models. The performance of the model is studied by simulating probability density functions (PDF) and cumulative distribution functions (CDF). Finally, we briefly outline some aspects of our future research works.

Abstract: To counter the problems associated with the conventional processes of producing implants, a new approach has been invented, which is the adaptation of the injection moulding process for manufacturing the fracture fixation plates. With this technique in place, we have now taken a step in the right direction towards rapid manufacturing of fracture fixation plates, for the first time. The fracture fixation plates produced using this technique comply with the international standards including MPIF Standard 35, ISO 5832-1 and ISO 10933. The advantages of the present invention are design flexibility, rapid manufacturing, cost effectiveness and minimal waste compared to conventional process

Abstract: The microstructures of laser welds of the near-β titanium alloy TLM were studied for substrates in the as hot rolled, solution treated and solution treated and aged conditions. Irrespective of substrate condition the fusion zone consists of a cellular β structure. Trends in bulk hardness of the various conditions seem to be carried through into the weld consistently across the profile. The hardness in the fusion zone remained similar to that of the bulk. However, a drop in hardness occurs in the HAZ. Lath that formed around the hardness indent of the fusion zone and HAZ suggest that the weld undergoes a martensitic transformation to α" during deformation.