Abstract: Energetic materials, particularly explosives materials, are detected in samples by heating a mixture of a sample under a reduced pressure of not more than 100 mbar and detecting the chemiluminescent emission therefrom with a suitable light detector, for example a photomultiplier or photodiode. The sample is heated to a temperature in the region of from 300° C. to 500° C., conveniently in a quartz tube furnace placed within a vacuum chamber. The inlet to the tube furnace may be connected directly into the outlet from a gas chromatography apparatus such that individual compounds from a mixture may be detected as they pas sequentially through the chromatography apparatus and into the tube furnace. An inert carrier gas may be used such as nitrogen, argon or helium or a specific gas to enhance the responsiveness of the method for a particular sample material. Apparatus for carrying out the method is also provided.

Abstract: The invention provides an extrudable gun propellant having a specific energy content of at least 1100 kJ/kg and typically over 1200 kJ/kg, but with reduced vulnerability to shaped charge attack compared to known colloidal propellants. This is achieved by using an energetic binder prepolymer and an energetic plasticiser with a reduced content of explosive filler. The composition comprises 65-85% by weight particulate explosive filler, 10-30% by weight of a mixture of a funtionally-terminated poly(nitratoalkyl-substituted)alkyl ether prepolymer and a cross-linking agent, and 1-12% by weight of energetic plasticiser.

Abstract: An X-ray inspection system comprises an X-ray source (1) disposed to irradiate an object to be inspected (4) with a beam of X-rays in the form of a fan project from the source (1) through the object (4), detection means (6) capable of discriminating between the intensitities of X-rays coherently scattered through the object (4) at different angles to produce an output signal dependent on the intensity of the X-rays scattered through each of those angles and analyzing means (not shown) operably connected to the detention means (6) to process the output signal to determine the presence of X-rays coherently scattered through one or more pre-determined angles. Collimination means (23) is provided between the detection means (6) and the object (4) and is adapted to pass only X-rays coherently scattered at the different angles from a limited voxel (volume element) depth central at point P. Movement at the collimator (23) along the direction of the beam together with translation of the object by e.g.

Abstract: The synthesis of novel compound (I) is described: 5-bromo-2-iodopyrimidine may be used for the synthesis of a range of chemical compounds both known and novel. The synthesis of a number of novel liquid crystalline compounds is described.

Abstract: A ferroelectric liquid crystal display (FLCD), which comprises a cell including a layer of chiral smetic ferroelectric liquid crystal material contained between two substrates and at least one alignment layer for determining the surface alignment of the molecules in the liquid crystal material, is manufactured as follows. After selection of a suitable material for the alignment layer, the cell is filled by introducing liquid crystal material between the substrates to which the alignment layer is applied. After filling of the cell, a heat treatment is applied to the cell by raising the cell to an elevated temperature and maintaining the cell at that temperature for a predetermined period of time.

Abstract: For a liquid crystal display apparatus, an orientating film of an electrode substrate including more signal electrodes than scanning electrodes in a predetermined range receives a uniaxial orientation treatment parallelly or almost parallelly to a lengthwise direction of the signal electrodes. Besides, an orientating film of an electrode substrate including the scanning electrodes receives a uniaxial orientation treatment perpendicularly or almost perpendicularly to a lengthwise direction of the scanning electrodes. The electrode substrates are combined so that the directions of the uniaxial orientation treatment of the orientation films become parallel to each other. This enables growth of a smectic layer to be less frequently hindered by differences in level caused by the electrodes. Thus a uniform C2U orientation can be obtained easily. Consequently, the liquid crystal display apparatus realizes a uniform orientational state with no defects and uniform and high-contrast display properties.

Abstract: This invention relates to the manufacture of composite propellants containing rubbery binders and particulate non-binder ingredients. The process consists of curing a mixture of a functionally-terminated hydro-carbon prepolymer and a cross-linking agent to form a viscoelastic first binder composition, mixing the binder with non-binder ingredients to form a plastic propellant, and rubberising at least a part of the plastic propellant by adding to it a further quantity of the cross-linking agent, provided the propellant is formed into a propellant charge while still in a plastic state. The further quantity of the cross-linking agent may be mixed in with the plastic propellant prior to forming, or applied to the surface of the plastic propellant after having been formed into a charge.In a preferred embodiment of the invention, the prepolymer consists of an hydroxy-terminated polybutadiene having a molecular weight of about 3000 and a functionally of about 2.

Abstract: A ferroelectric liquid crystal display (FLCD), which comprises a cell including a layer of chiral smetic ferroelectric liquid crystal material contained between two substrates and at least one alignment layer for determining the surface alignment of the molecules in the liquid crystal material, is manufactured as follows. After selection of a suitable material for the alignment layer, the cell is filled by introducing liquid crystal material between the substrates to which the alignment layer is applied. After filling of the cell, a heat treatment is applied to the cell by raising the cell to an elevated temperature and maintaining the cell at that temperature for a predetermined period of time.

Abstract: A radiation field analyzer (10) provides means for analyzing the spatial mode spectrum of radiation received from a scene. In a multimode waveguide embodiment, light from a laser (24) is directed towards a scene through an alumina waveguide structure (12). A portion of the laser light is directed towards a mode generator (28) which selectively converts the laser radiation into one of a series of modes. Laser light returning from the scene is mixed with the light from the mode generator to produce interference signals. These signals are measured by a detector (34) and analyzed by a programmed computer (36). By sequentially altering the mode generated by the generator (28) and analyzing the resulting signals, a spectrum of the modes returning from the scene is obtained.

Abstract: Porous semiconductor material in the form of at least partly crystalline silicon is produced with a porosity in excess of 90% determined gravimetrically, and voids, crazing and peeling are substantially not observable by scanning electron microscopy at a magnification of 7,000. The porous silicon is dried by supercritical drying. The silicon material has good luminescence properties together with good morphology and crystallinity.

Abstract: Ferroelectric liquid crystal devices are described which contain liquid crystal mixtures comprising components A and B. Component A consists of one or more optically active compounds capable of imparting a spontaneous polarization to the material. Component B is selected as one or more compounds having formula (I), wherein a, b and c are independently 0, 1, 2; R.sub.1 and R.sub.2 are C.sub.1-15 straight or branched chain alkyl or alkoxy, preferably C.sub.3-12. In the above (for component B) CH=CH linking groups may be replaced by C.sub.2 H.sub.4 and CH.sub.2 O linking groups may be replaced by OCH.sub.2.

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: Substituted phthalocyanines of a formula (I) ##STR1## wherein M is a metal atom or a metal halide or oxide, or M is 2H, one H being bonded to each of the bonding N atoms (29 and 31 positions) shown, R.sub.1 to R.sub.8 are the same or different and are independently selected from C.sub.1 to C.sub.20 alkyl, C.sub.1 -C.sub.20 alkenyl, --X--COO--X.sup.1, --X--O--Y, .alpha., and --X--COZ where X is independently selected from a chemical bond, (--CH.sub.2).sub.n where n=0-20 or (CH.sub.2).sub.n --CH.dbd.CH (--CH.sub.2).sub.b where a and b are independently selected from 0-20 and a+b is in the range 0-20, X.sup.1 is independently selected from C.sub.1 -C.sub.20 alkyl or C.sub.2 -C.sub.20 alkenyl, Y is independently selected from C.sub.1 -C.sub.20 alkyl, C.sub.2 -C.sub.20 alkenyl or H and Z is selected from OH or NR.sup.1 R.sup.11 where R.sup.1 and R.sup.11 are independently selected from H, C.sub.1 -C.sub.20 alkyl and C.sub.2 -C.sub.

Abstract: A light emitting device (10) incorporates a layer (12) of porous silicon of low dimensionality surmounted by a discontinuous layer of silver in the form of discrete islands (20). A digitated electrode (13) is connected to the islands (20). The islands (20) have diameters in the range 5 nm to 20 nm and spacings in the range 10 nm to 50 nm, and they form a Schottky diode structure on the silicon (12). Under electrical bias, the diode structure conducts and light is generated. The device (10) is produced by vacuum deposition of silver onto a silicon wafer at a temperature which provides for the silver to separate into individual balls (20). The wafer is then anodized to produce a porous layer incorporating columns of silicon and silicon dioxide surmounted by respective silver islands (20). Each silver island (20) protects the underlying silicon (21) from the anodizing medium, and subsequently provides an electrical contact to the silicon.

Abstract: The invention relates to a dielectric resonator antenna system which exhibits an unusually wide bandwidth. This is achieved by chosing a patch antenna/dielectric resonator combination with shape and dimensions such that resonance modes over a continuous range wavelengths can be established therein. The bandwidth and transmission properties of the device are further improved by including a dielectric coupling element (between the dielectric resonator and air) whose antireflection characteristics are optimized for a wavelength which is slightly different from the maximum wavelength of the patch antenna.

Abstract: The low peel strengths of diffusion bonded joints in aluminum alloy structures has been a bar to their use in superplastic forming. The invention overcomes this disadvantage by creating a workpiece intended for subsequent superplastic forming by diffusion bonded assembly of alloy sheets (30-32) in bonding zones according to a predetermined pattern and providing reinforcing material (33) in the workpiece in the region of the diffusion bonded zones. The reinforcing material serves to prevent the tensile stresses exerted during subsequent superplastic forming from initiating peel fracture of the diffusion bonds. Instead, the tensile stresses act so as to bring about superplastic deformation in those regions of the workpiece between the diffusion bonded zones.

Abstract: An electro-optical device is arranged as a Fabry Perot etalon comprising two mirrors and a central region. The mirrors are multilayer heterostructures of Al.sub.x Ga.sub.1-x As semiconductor materials where x alternates between 1.0 and 0.3. The central region may be a multiple quantum well structure of Al.sub.x Ga.sub.1-x As where x alternates between 0 and 0.3. The etalon material doping is non-uniform so that it is electrically a semiconductor device with a biasable central region. The optical path length in the central region is electric field dependent, and the etalon transmission or reflection is accordingly modulatable by varying the central region bias. The mirrors may be heavily doped and of opposite conductivity type with the central region undoped. This provides a PIN diode. Light incident on the etalon executes multiple transits of the central region.

Abstract: In the production of alloy by evaporation from an evaporation bath and condensation under vacuum, charge replenishment is achieved by a procedure involving bleeding charge from the bath and admixing the bled charge with replenishment material and introducing replenishment from the admixture. An apparatus for use in the process comprises a mixing passageway encompassing an evaporation bath and distributed sub-surface bleed ports and feed ports linking the evaporation bath and the mixing chamber. Flow of metal through the ports is induced by pumped circulation in the mixing chamber. The circulation is turbulent for good mixing of the metals.

Abstract: Aluminium alloys having compositions within the ranges (in wt %) 2 to 2.8 lithium--0.4 to 1 magnesium--1 to 1.5 copper--0 to 0.2 zirconium--0 to 0.5 manganese--0 to 0.5 nickel--0 to 0.5 chromium--balance aluminium. The alloys are precipitation hardenable and exhibit a range of properties, according to heat treatment, which make them suitable for engineering applications where light weight and high strength are required.

Abstract: A fibre reinforced composite comprises one or more layers of unidirectional non-woven fibres alternated with one or more layers of woven fibres, preferably in a satin, embedded in a plastics matrix.