Abstract: An electroluminescent device (10) comprises a porous silicon region (22) adjacent a bulk silicon region (20), together with a top electrical contact (24) of transparent indium tin oxide and a bottom electrical contact (26) of aluminum. The device includes a heavily doped region (28) to provide an ohmic contact. The porous silicon region (22) is fabricated by anodizing through an ion-implanted surface layer of the bulk silicon. The silicon remains unannealed between the ion-implantation and anodization stages. The device (10) has a rectifying p-n junction within the porous silicon region (22).

Abstract: A ferroelectric liquid crystal display comprises an addressable matrix of pixels, and addressing circuitry for selectively addressing each pixel in order to vary the transmission level of the pixel relative to the transmission levels of the other pixels. The addressing circuitry includes spatial and/or temporal dither circuits for addressing separately addressable subpixels with different spatial dither signals and/or for addressing each pixel or subpixel with different temporal dither signals in separate subframes.

Abstract: An antenna system for providing radiation over substantially 360.degree. in azimuth by illuminating a conical reflector with a radiation beam having a frequency distribution with a local minimum which is coincident with the point of the reflector thus avoiding scattering. Preferably the radiation intensity distribution is annular, most preferably being Laguerre-Gaussian in nature.

Abstract: 1,2 and 1,3-dinitrate esters are prepared from polyols containing 1,2- or 1,3-diol fragments using an alkyl or aryl boronic acid to form a cyclic boronate ester derivative which is then reacted with dinitrogen pentoxide to directly generate the dinitrate ester. In the cyclic ester from the 1,2- or 1,3-hydroxyl groups are protected and other reactions may then be carried out on other parts of the molecule of which the fragment form a part, leaving the dinitrate ester to be produced subsequently in the final step. High yields are obtained at both stages.

Abstract: An electro-optical detection system for detecting objects embedded in a partially transmitting medium. The system includes a receiver for receiving electromagnetic radiation and a device for separating the received radiation into two separate spectral channels. A detector in each of the spectral channels for providing a signal indicative of the received radiation in each spectral channel. A signal processor, responsive to the outputs of the detectors, having a signal channel where transmission of light of the signal channel wavelength in the medium is high and having a reference channel where attenuation of light of the reference channel wavelength in the medium is high. The signal processor ensures that the reflected light at both signal and reference wavelengths are of similar intensity and geometric distribution. A subtractor provides a difference output in which the signal and reference channels are subtracted, removing the effect of reflected light.

Abstract: A relatively fast process for producing HNS from trinitrotoluene (TNT) in high yield consists of oxidizing TNT with an oxidizing transition metal compound within a polar aprotic solvent having a weak base, such as an alkali metal carboxylate, dissolved therein. The amount of transition metal compound used is typically at least one mole per mole of TNT. An especially preferred transition metal compound for use in the present process is cupric chloride.