The study of metal ion release and cytotoxicity in Co–Cr–Mo and Ti–Al–V alloy in total knee prosthesis – scanning electron microscopic observation

We surgically retrieved two cobalt(Co)–chromium(Cr)–molybdenum(Mo) and five titanium(Ti)–aluminum(Al)–vanadium(V) alloy knee prostheses from patients because of mechanical failure and pain. We examined the distribution of the small particles which were released from the Co–Cr–Mo and Ti–Al–V alloys using a backscattered scanning electron microscopy (SEM). In addition we analyzed the metals in the artificial knee joints and the tissues adjacent to them using energy dispersive X-ray spectroscopy (EDS). We demonstrated that a myriad of fine particles, produced by the abrasion of both Co–Cr–Mo and Ti–Al–V alloys, accumulated in the synovial cells. As Co–Cr–Mo alloys disintegrate easily in the cells, Co dissolves from the peripheral areas of them, although Cr remains within the cells. In contrast Ti–Al–V alloys are very stable in the synovial cells. From these findings we conclude that the Co–Cr–Mo alloys are hazardous to the body as the alloys release Co which enters the body. In contrast the Ti–Al–V alloys are very stable and are patently safer. Artificial joints, however, are still in considerable need of improvement.     

Effect of heating temperature on dielectric properties of Pb(Zr,Ti)O3 [PZT] fibers

Ferroelectric Pb(Zr_0.53Ti_0.47)O₃ fibers were reproducibly fabricated by sol-gel technique using triethanolamine (TEA) complexed alkoxide. The phase transition from pyrochlore to perovskite took place about 400°C and a stable single perovskite phase was obtained at 550°C. PZT gel fibers spun through nozzle were heat-treated at 700°C, and at 1000°C for 1 h to certify the effect of heat-treatment temperature on the electrical properties. The PZT fibers had elliptical cross sections with diameter of 72 m–92 m, and dense microstructure was obtained by heating at 1000°C. In the PZT fibers heat-treated at 1000°C, a distinguishable relative permittivity peak and a pyroelectric current peak were observed at their Curie temperature. The P-E hysteresis loops of the crystalline PZT fibers were also observed.     

A location model for smart environments

This paper presents a location model for location-aware and user-aware services in smart environments. It can be dynamically organized like a tree based on geographical containment, such as that in a user–room–floor–building hierarchy and each node in the tree can be constructed as an executable software component. The model is unique in existing approaches because it enables location-aware services to be managed without any database servers, it can be managed by multiple computers, and it can provide a unified view of the locations of not only physical entities and spaces, including users and objects, but also computing devices and services. A prototype implementation of this approach was constructed on a Java-based mobile agent system. This paper presents the rationale, design, implementation, and applications of the prototype system.     

Stress intensity factor analysis of a three-dimensional interface crack between dissimilar anisotropic materials

A new numerical method to calculate the stress intensity factors (SIFs) of a three-dimensional interface crack between dissimilar anisotropic materials was developed. In this study, the M-integral method was employed for mode separation of the SIFs. The moving least-square method was utilized to calculate the M-integral. Using the M-integral with the moving least-square method, SIFs can be automatically calculated with only the nodal displacements from the finite element method (FEM). Here, SIFs analyses of some typical three-dimensional problems are demonstrated. Excellent agreement was achieved between the numerical results obtained by the present method and the corresponding results proposed by other researchers. In addition, the SIFs of a single-edge crack, a through crack, and a semi-circular crack between two anisotropic solids in three-dimensional structures were analyzed.     

Shape oscillation of bubbles in a row excited by ultrasonic vibration

Behaviors of bubble(s) exposed to an ultrasonic vibration are focused. Size of the bubbles interested in the present study is of O(1 mm) in diameter. The bubbles were injected through the micro syringe to the test fluid (water or water/surfactant mixture) filled in the rectangular tank. Ultrasonic vibration was irradiated to the bubble(s) after the detachment of the bubble from the tip of the syringe; thus the bubbles were exposed to the periodic oscillation in rising the test fluid. The authors clearly detect radial and shape oscillations under the large-amplitude vibration by use of high-speed camera. Preferable mode number of the shape oscillation, and the transition process from the radial to the shape oscillation are discussed.     

煤和污泥燃烧和气化过程中汞析出行为的研究

固体燃料和固体废物在燃烧和气化过程中的汞排放问题在全球已经受到广泛关注。该文首先选取3个煤种和3种干城市污泥作为样本，通过热重(TG)实验了解汞在燃烧和气化过程中的基本析出行为。然后选取一个污泥样在滴管炉里燃烧，研究汞在接近实际燃烧状况下的析出行为。通过热平衡计算预测了在和实验相同条件下汞析出的变化趋势。结果表明，污泥燃烧过程中汞的析出行为受到污泥中硫和固定碳含量的抑制，煤燃烧过程中汞的析出行为受到煤中固定碳含量和Cl含量的重要影响。另外，因为单质汞在还原性气氛下极易形成，在气化过程中，即使是低温汞也很快析出。     

COMPUTATIONAL METHODS THROUGH GENETIC ALGORITHMS FOR OBTAINING STACKELBERG SOLUTIONS TO TWO-LEVEL MIXED ZERO-ONE PROGRAMMING PROBLEMS

In this paper, we develop computational methods for obtaining Stackelberg solutions to two-level mixed zero-one programming problems in which the decision maker at the upper level controls zero-one variables and the decision maker at the lower level controls real variables. To illustrate two-level mixed zero-one programming problems, we formulate a facility location and transportation problem as a two-level mixed zero-one programming problem. We develop computational methods through genetic algorithms for obtaining Stackelberg solutions. To demonstrate the feasibility and efficiency of the proposed methods, computational experiments are carried out and comparisons between the methods based on the branch-and-bound techniques and the proposed methods are provided.     

Shear viscosity of the B phase of superfluid3He

The shear viscosity (T) in the Balian-Werthamer (BW) state of superfluid ³ He is calculated variationally throughout the region 0t 1(t=T/T _c) from the transport equation for Bogoliubov quasiparticles. Coherence factors are treated exactly in the calculation of the collision integral. The numerical result for =_s= _s(T)/_n(T_c) agree very well with experiment in the range 0.8t1.0. Analytic expressions = 0.577 (1–1.0008t) and =1–(23/64) [=(T)/k _B T] are obtained in the low-temperature region and in the vicinity ofT _c, respectively. From the numerical analysis it is shown that the latter equation is valid only in the temperature range 0.9997t1.0.Supported by the Research Institute for Fundamental Physics, Kyoto University.