Medical implant devices are being increasingly used to replace or stimulate damaged or diseased body parts. Because the body rejects any foreign matter, these components should appear, to the body, to be of natural or nonforeign material. An obvious approach is to construct prosthetics or other implant devices of “natural” material, such as bone mineral. While this can be done, in practice it is not feasible for large components since bone mineral does not possess sufficient structural or mechanical strength. Furthermore, items such as pacemakers or electrodes cannot be fabricated from bone mineral.

Since it is the surface of the medical implant that is in direct contact with the body, one solution in designing the device is to choose the bulk material for mechanical strength or other properties and to hide the surface of the device with a coating of biocompatible material. Since bone mineral is one of the most biocompatible materials known, much effort has been devoted to developing surface treatment processes to deposit this material on prosthetics and other implants.

The material bones and teeth are composed of is quite complex. Tooth enamel, itself a coating, is very durable and primarily composed of a hydrated form of calcium phosphate called hydroxylapatite (Ca10(PO4)A(OH)2), or HA. Bones are approximately 60–70% HA. However, it is not sufficient to simply produce a coating with the same chemical constitutents as HA.

Since the discovery by Karl Alex Muller and Johannes Georg Bednorz (IBM Zurich) in January 1986 that an oxide of barium, lanthanum and copper might be superconducting at temperatures up to 35 K, the superconducting transition temperature has jumped to 125 K in only two years. A great tide of high Tc superconductor exploration has swept across the world. Like their counterparts in other countries, Chinese scientists also stood in the frontline of this revolution.

When Prof. Zhao Zhongxian obtained Bednorz and Müller's paper in September 1986, he thought their ideas were reasonable. A team at the Institute of Physics, Academia Sinica was then organized to search for high Tc materials. In December 1986, Zhao and his colleagues successfully obtained superconducting samples of Sr0.25La4.75Cu5Ox with onset temperature Tcon 48.6 K and Ba0.5La4.5Cu5Ox with Tcon = 46.3 K (Figure 1). This occurred only a few days after the announcement of the confirmation of superconductivity by diamag-netic observation from Japan. These were the highest records for superconducting transition temperature Tcon in the world at that time. Moreover, a sign of superconductivity with Tc0 (zero resistivity) around 70 K was also observed in some La-Ba-Cu-O samples. Because these samples were unstable, however, the Tc decreased after several days storage in air. Since then Zhao and his colleagues have searched for materials with higher Tc by using various compositions and substitutions, different sintering processes, and heat treatments.

If you are an economist in this day and age, and especially if you are an economist at MIT, you often get asked “Is economics really a science?”

I used to give a very complicated answer to that question, but recently I discovered a much simpler one: When the Discovery went up, the Space Administration announced that the success of the Discovery was entirely due to the scientific achievement of economists because in shifting from the Challenger to the Discovery the Space Aclrninistration had to do a lot of experiments, and they had to replace rats with economists in all these experiments. They announced three reasons for replacing rats with economists: First, there were now more economists and they were cheaper; second, you sometimes emotionally get attached to the rats; and third, there are some things that rats just won't do.

The serious answer to that question, however, is that economics is much like geology. Geologists understand earthquakes and volcanoes perfectly—it's plate tectonics. But if you ask a geologist, “Tell me the precise timing and the precise magnitude of the next earthquake in Los Angeles,” you are in trouble.

The problem is that people like to ask economists that question: “Give me the precise timing and the precise magnitude of some event.” And economists have a character weakness. They tend to answer those kinds of questions. And those kinds of questions simply can't be answered.

The Center for Micro-Engineered Ceramics (CMEC) recently established at the University of New Mexico is a National Science Foundation Industry/University Cooperative Research Center. It is supported by the National Science Foundation, Los Alamos and Sandia National Laboratories, New Mexico Research and Development Institute, and the ceramics industry.

The CMEC is unique in that it combines the resources of two universities (University of New Mexico and New Mexico Institute of Mining and Technology) and two national laboratories to attack ceramics-related basic research problems of industrial significance. An essential part of the effort is the strong interplay between the basic scientific disciplines, particularly physics and chemistry, along with engineering; the work is interdisciplinary with members from chemical engineering, mechanical engineering, chemistry, physics, and geology.

The goals of the CMEC are to

1. Aggressively attack ceramics-related basic research problems using university/national laboratory/industry collaborations;

2. Transfer technology between the universities, national laboratories, and industry; and

3. Train a new generation of ceramic scientists and engineers at both the undergraduate and graduate levels.

At present, the areas of major interest are novel powder synthesis and processing schemes for controlled morphology powder compacts, and coatings and porous films. In addition, both laboratories and universities have programs on ceramic superconductors.