Transplantation of both kidneys of an anencephalic newborn to a 23-year-old patient

Both kidneys of an anencephalic newborn were transplanted into a 23-year-old male patient. Hemodialysis was required for 3 weeks postoperatively. Both organs increased in size but did not reach the normal volume of an adult kidney. 3 years post-transplantation, the patient is doing well with a plasma creatinine level of 1.5 mg/dl. Technical problems are discussed.     

A comparative study of a fluidised bed reactor and a gas lift loop reactor for the IBE process. Part II: Hydrodynamics and reactor modelling

A fluidised bed reactor with liquid recycle (FBR) and an external loop gas lift reactor (GLR) were designed for the production of isopropanol—butanol mixtures by immobilised Clostridium spp. and scaled down to laboratory scale (part I). Hydrodynamic models were set up for the two laboratory scale reactors. Liquid mixing in the 10 dm³ FBR was described by 10 tanks in series. Fluidisation velocities, bed expansions and axial dispersion coefficients agreed well with literature data. Liquid mixing in the 15 dm³ GLR was described by 100 tanks in series. The gas hold-up and circulation velocity were found to decrease with increasing hold-up of solids, in accordance with literature indications. No influence of the hold-up of solids on the axial dispersion coefficient was determined. An integrated reactor model was set up for both reactors, using the hydrodynamic and kinetic model. Actual fermentation data are presented and compared with model predictions in part III of this study; this part will also include a comparison of reactor performances and scale up aspects.     

Simple and precise measurements of fibre volume and void fractions in metal matrix composite materials

A method for determining the fibre volume fraction, V _f and the void fraction, V _g, in a metal matrix composite (MMC) material is described. These quantities are determined from specimen weight measurements in air and in a liquid using a laboratory balance. For a material without voids, V _f can be determined with an uncertainty less than 0.5% with a balance precision of 0.01%. By making the same measurements before and after etching away the matrix, using the same balance precision, V _f and V _g can be determined to an uncertainty of about 3 and 6%, respectively. It is also shown theoretically that by indenting a specimen containing no fibres and only a uniform distribution of small voids, the void fraction can also be determined from weight measurements before and after indentation.     

Theory of electrical resistivity of metal-matrix composites at cryogenic and higher temperatures

This paper presents a theory describing the electrical resistivity (conductivity) in the axial direction of unidirectional fibre-reinforced metal-matrix composite (MMC) materials at cryogenic and higher temperatures. The theory is derived from the solution of Boltzmann's equation. A triple-integral expression is obtained to describe the change in the electrical conductivity in the matrix metal due to electron scattering from the fibre surfaces. It is shown that at cryogenic temperatures, the electrical resistivity can rise by a factor of 2200 over a decrease in temperature of about 6 K below about 10 K. This effect is due entirely to electron scattering from fibre surfaces. The model developed shows that the composite resistivity agrees well with known experimental data at temperatures above 80 K. At very low temperatures, _c (T) _c (T _R) (1–CT ^–4)^–1, whereT is the absolute temperature. Shortcomings and implications of the theory are discussed.     

Direct measurements of non-linear stress-strain curves and elastic properties of metal matrix composite sandwich beams with any core material

A theory for measuring non-linear stress-strain curves and elastic properties of metal matrix composite (MMC) sandwich beams subjected to pure bending loads is discussed. The beam is made from any core material sandwiched between an upper facing of unreinforced metal and a lower facing of MMC with unidirectional fibre reinforcement or vice versa. The model developed shows that the determination of the position of the neutral axis is critical to the measurements discussed in this paper. The analysis removes the restriction of the effects of the core. With the aid of this model, we show that the position of the neutral axis can be determined directly from surface strain measurements. Measurements of neutral axis position lead directly to the determination of the beam elastic properties and, thus, directly obtained from surface strain measurements. It is shown that the model predicts longitudinal stresses and strains within any layer of the beam. The analysis includes the limiting case of a very weak core material. A consequence of this model is the determination of the MMC facing fibre volume fraction. A detailed error analysis predicts that the longitudinal elastic modulus of an MMC material facing can be obtained with an uncertainty between 4 and 6% if the surface strain measurements and beam dimensions can be obtained with an uncertainty of 1%. The volume fraction can be obtained within 10% uncertainty, although better methods are available for that measurement.