Abstract: The invention concerns a preparation process of a hybrid organic-inorganic material including the following successive steps: a) preparation of a neutral organosilicon sol in at least one organic solvent, b) incorporation of a doping agent into the neutral organosiliconsol, and production of a doped sol, c) incorporation into the doped sol, of an accelerating agent in order to activate the subsequent gelation of the sol, d) condensation of the sol in order to obtain a crosslinked gel, e) drying of the gel and production of a stable doped gel. and the material obtainable by such a method.

Abstract: This invention describes a method for the loading and alignment of elastomers in electro-optic and electro-active devices. It comprises the in-situ polymerization between substrates of liquid crystal monomers in the presence of cross-linking reagents. It also describes the production of free-standing elastomer films.

Abstract: A treatment process for a composite comprising a matrix of a precipitation hardenable aluminum alloy and a particulate or short fiber ceramic reinforcement. The process includes hot and/or cold working the composite, subjecting the composite to a controlled heating step in which the composite is raised from ambient temperature to a temperature of from 250 to 450.degree. C. at a rate of temperature increase less than 1000.degree. C. per hour, and subjecting the resulting heat treated composite to a solution treating step.

Abstract: A method for manufacturing optical components having a periodic or quasi-periodic structure such as diffraction gratings, volume holograms or distributed feedback mirrors in optical fibers. An optical medium is subjected to acoustic waves which induce periodic or quasi-periodic changes in the optical properties of the medium, the changes being at least partially retained on removal of the waves. The changes may result from stress associated with the antinodes of an acoustic standing wave, alteratively the stress distribution associated with a travelling acoustic wave in an electro-viscous liquid may be semi-permanently retained by the solidification of the material resulting from the application of an electric field.

Abstract: Multiplex addressed ferroelectric liquid crystal devices containing liquid crystal mixtures composed of components A, B and C. Component A consists of one or more optically active compounds capable of imparting a spontaneous polarization to the material. Component B is a compound or compounds of the formula: ##STR1## where R.sub.1 and R.sub.2 independently represent straight or branched chain C.sub.3 -C.sub.12 alkyl or alkoxy groups, a, b and c are independently 0, 1 or 2 and the total of a+b+c is not greater than 4. Component C is selected from a range of liquid crystal components.

Abstract: A novel LCP material based on fumarate and maleate di-esters is disclosed having general formula (I); R.sub.1 and R.sub.2 may may not be the same but have general structure (II); (a)=(b), (c), (d); p=2 to 14; q=0 or 1; r=1 or 2; s=1 or 2; X.dbd.O, CO.sub.2, O.sub.2 C, CH.sub.2 ; Y.dbd.C.sub.2 H.sub.4, O, CO.sub.2, O.sub.2 C; Z.dbd.CN, halogen, R, CO.sub.2 R, OR, O.sub.2 CR, wherein R=chiral or achiral.

Abstract: Liquid crystal compounds having the formula (I) ##STR1## in which A.sub.1 is alkyl, alkoxy or alkenyl; X.sub.1, X.sub.2, X.sub.3 and X.sub.4 are independently halogens, m, n, p and q are independently 0, 1, 2, 3 or 4 such that m+n+p+q.noteq.0; Y is O or COO; and A.sub.2 is an end group of the formula (II), ##STR2## where Z is halogen, CH.sub.3, CN, CF.sub.3 or, CHF.sub.2 ; R is a linear or branched alkyl group or H; and R.sub.1 is a linear or branched alkyl group or H.

Abstract: Liquid crystal compounds of the formula:R.sup.1 --Z.sup.1).sub.m --(Z.sup.2)--X--(Z.sup.3)--(Z.sup.4).sub.n --R.sup.2These compounds may be mixed with other liquid crystal compounds to give liquid crystal mixtures which may then be used in liquid crystal devices. In the formula X is COS, CSS and CSO; each of Z.sup.1, Z.sup.2, Z.sup.3, and Z.sup.4 are independently phenyl, substituted phenyl, where substitution is lateral substitution selected from F, Cl, Br, NO.sub.2, CN, NCS; naphthalene, substituted naphthalene, where substitution is lateral substitution selected from F, Cl, Br, NO.sub.2, CN, NCS, CH.sub.3 ; thiophene, pyridine and pyrimidine; each of A.sup.1 and A.sup.2 is independently selected from single bond, C.tbd.C, CH.dbd.CH; A.sup.3 is selected from C.tbd.C and single bond; each of R.sup.1 and R.sup.2 are independently selected from CN, NCS, CH.dbd.C(CN).sub.2, C.tbd.C--CN, C.tbd.C--CF.sub.

Abstract: A microwave connector comprises two substrates arranged in orthogonal planes. A first substrate (2) is formed as a microstrip system (8) with a microstrip component (3) connected via a quarter wavelength taper (4) to a parallel transmission line (5). This transmission line terminates in a short circuit (15) to a ground electrode (7) on the back of the microstrip. A second substrate (10) is formed as a slotline system (9) having a slotline (13) between two sheet electrodes (14). In this slotline is a slot (16) of dimensions slightly less than the slotline width and sufficient length to accommodate the microstrip. The microstrip and slotline are electrically unconnected. Energy transfer between microstrip and slotline, or vice versa, takes place by electromagnetic coupling between the transmission line and the edges of the slotline. The slotline may be formed with an additional substrate and slotline electrode in a triplate configuration. Several microstrip components (8.sub.1 to 8.sub.