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A porous silicon layer (PSL) with pores of 40-200A diam was electrochemically treated at cathodic potentials in an aqueous KC1 solution. The treatment gave rise to the increase in proportion of silicon oxides. The surface had a porous structure of 0.5-2 t~m diam after the electrochemical treatment. A comparison study using He-Ne laser irradiation of the PSL was done that showed no distinct effects in the cathodic reaction rate compared with the electrochemical method. A surface-type humidity sensor was fabricated using the electrochemically treated silicon and found to be sensitive to changes in humidity over a wide range.

Non-contact measurement of torsion on a rotating shaft was done with fibre Bragg gratings and involved the use of graded index lenses for transmitting optical information between the light source and the gratings, and back to a spectrum analyser. Special Böhler steel with high yield strength was used for the shaft. For the experimental measurements, one end of the shaft was clamped in a lathe chuck, and the other end was fixed to a brake system, allowing the application of torque on the rotating shaft. Up to 97 N m of torque was applied to the shaft rotating at 190 rpm, and the results were very close to the expected values. Whereas torsion changes the differential-mode wavelength of the gratings in the proposed configuration, this wavelength difference is insensitive to temperature. For the particular system investigated experimentally, the differential wavelength change was 7.4 pm N −1 m −1 , and the corresponding temperature sensitivity was −0.547 pm • C −1 .

We present measurements of the electrical resistivity ρ(T ) on high-quality single-crystalline CeNiSn under both hydrostatic pressure up to 1 GPa and uniaxial pressure up to 0.25 GPa. At ambient pressure, ρ(T ) along the orthorhombic a-axis (b-axis) shows two maxima at T L = 12 K (14 K) and T H = 74 K (40 K), respectively, which arise from the Kondo scattering of conduction electrons by the crystal-field ground state and excited states. With increasing hydrostatic pressure, both T L and T H increase linearly, and for P 0.8 GPa, the anisotropy in ρ(T ) for I a and I b almost vanishes as a result of increased hybridization between the 4f electrons and the conduction electrons. Under P a, both T L and T H in ρ(I b) increase similarly to under hydrostatic pressure. Under P c, however, the depression of T L in ρ(I a) and ρ (I b) suggests that the c-f hybridization in the crystal-field ground state is weakened in the a-b plane of CeNiSn.