Abstract: An apparatus and method for open-path gas detection. The apparatus includes a radiation source and first and second radiation detectors sensitive to radiation in first and second spectral bands. The long cut-off wavelength of the second spectral band is longer than the long cut-off wavelength of the first spectral band, and the short cut-off wavelength of the second spectral band is shorter than the short cut-off wavelength of the short spectral band, such that the second spectral band is wider than and completely overlaps the first spectral band. Radiation from the radiation source passes through the area to be checked for gas, and is partially absorbed if gas is present. The path between the radiation source and the first and second radiation detectors need not be enclosed, and may exceed 100 meters in length. A processor compares intensity signals from the radiation detectors with a threshold value, and generates an output signal indicating a presence of gas based on the comparison.

Abstract: A medical device for insertion into human body having an echogenic portion of enhanced visibility in an ultrasound scan. The echogenic portion includes an echogenic material comprising a plastic impregnated with sonically reflective particles, the particles having an average size of less than 500 nanometers and formed of a substance having a specific gravity of 5 or greater. Preferably the particles have an average size of less than 100 nanometers and the sonically reflective particles are 5% to 40% of the echogenic material.