Abstract: An irreversible phototropic material consists of a plasticized matrix in which is suspended a phototropic transition metal salt and an additive which inhibits the production of haze in the phototropic material. Generally the additive is a substance which inhibits the reduction of the transition metal in the transition metal salt from a higher to a lower oxidation level. Suitable substances include chelating agents such as oxalic acid, ethylenediamine and EDTA, and oxidizing agents, such as chromium trioxide. The transition metal salt is preferably copper (II) chloride or a mixture of copper (II) chloride and bromide, while the matrix is preferably polyvinyl chloride or polyvinyl chloride/polyvinylidene chloride copolymer.These phototropic materials may be used in protective devices, such as goggles and windows, to protect objects or subjects against intense radiation.

Abstract: A liquid crystal composition suitable for use as a two-frequency material in a two-frequency switching device comprises a mixture of:a first component comprising at least one diester compound having a formula: ##STR1## where R.sub.1 is an alkyl or alkoxy group, Z is an cycloalkyl or aryl ring structure and R.sub.2 is alkyl, alkoxy or halogen; or CN; and a second component comprising at least one compound having a formula: ##STR2## wherein R.sub.3 and R.sub.4 is each independently an alkyl or alkoxy group, ##STR3## is a trans-1,4-disubstituted cyclohexane or a benzene ring, Y is a cycloalkyl ring or a benzene ring optionally having a lateral halogen substituent and n is 0 or 1.

Abstract: A method for fusion welding together two portions of a parent metal comprised by an aluminum alloy includes the steps of surface abrading the two portions in at least the region of their mutual interface and intended weld zones, applying to each abraded surface a hot-sprayed coating comprised by a metal having a lower electrochemical potential than the parent metal, abutting the two coated portions at the mutual interface, and fusing them together by fusion welding.

Abstract: A pump for supplying liquid fuel to an engine and which incorporates means, in the form of shear members, for degrading an anti-misting additive in the fuel.

Abstract: A foldable, multi-hull pontoon suitable for use in bridging or as a ferry, has a sequence of trapezoidal hull plates (1) successively hinged to one another at their parallel edges so as to fold in concertina fashion, alternate pairs of the plates being mutually and transversely webbed at each end with collapsible triangular bulkheads (7) which define with the hull plates a series of triangular section hulls (13). Gunwale spacing beams (40) are provided to stabilise the opened pontoon and to provide trackways.

Abstract: A head up display system including a light emissive object at an object plane and a collimator and combiner to provide a collimated image for viewing at an eye plane overlaid on a view through the combiner. The object emits light in at least two chromatically separated emission wavebands and by a diffractive optical element in the light path from object plane to eye plane having narrow band reflection characteristics at each emission wavelength.

Abstract: A coating having low absorbance of laser energy is provided on optical components substrates by molecular beam epitaxial growth techniques.The growth conditions prevent contamination of substrate and coating with water and carbonaceous gases. The method of coating has the following steps:arranging the substrate in a vacuum chamber,cleaning the component while holding the pressure below 10.sup.-4 millibar and the partial pressure of H.sub.2 O and carbonaceous gases below 4.10.sup.-9 mb,applying at least one layer of a coating material to the substrate, while holding the pressure below 10.sup.-8 mb and the partial pressure of H.sub.2 O and carbonaceous gases below 4.10.sup.-9 mb.The optical component may be lenses, windows, or reflectors e.g. of ZnSe, GaAs, glass, etc. The coating may be of selenide e.g. ZnSe, etc.

Abstract: A carrier shell for secondary projectiles having a shell casing, a plurality of secondary projectiles within the casing, an explosive dispersal charge for dispersing the projectiles and a safety device having a body closing a venting aperature in the casing. A first mechanical connection secures the body to the casing and yields on detonation of the charge before firing to vent any explosion before firing without dispersing the projectiles. A second mechanical connection is moved in response to firing to a condition preventing venting.

Abstract: A digital storage device comprises a crystalline substrate such as silicon in which pockets of amorphous substrate material represent one of the binary logic states; the absence of amorphous material represents the other logic state. The amorphous material is formed by irradiation with a laser beam. Typically the radiation for silicon is at 347 nanometers, 2.5 nanosecond pulse length. The power density varies with crystalline orientation; for (001) silicon it is typically 0.3 J/cm.sup.2 and for (111) silicon it is 0.3 to 0.6 J/cm.sup.2. Erasure of the information is achieved by laser annealing the amorphous material back to its crystalline form.

Abstract: A liquid crystal composition includes at least one compound of Formula (I) as follows:A--CH.sub.2.CH.sub.2 --B Formula (I)where A and B are substituted ring structures which include terminal alkyl groups, A being selected from: ##STR1## where R'.sub.1 is an alkyl group R.sub.1, an alkoxy group R.sub.1 O, an alkylcarbonyloxy group R.sub.1 CO.O or an alkoxycarbonyloxy group R.sub.1 OCO.O; ##STR2## where R.sub.1 is an alkyl group; or ##STR3## where R.sub.1 is an alkyl group; and B being selected from: ##STR4## where R'.sub.2 is an alkyl group R.sub.2, an alkoxy group OR.sub.2, an alkylcarbonyloxy group OCO.R.sub.2 or an alkoxycarbonyloxy group OCO.OR'.sub.2 ; and X is hydrogen or a cyano group or a methyl group or a halogen; ##STR5## where R.sub.2 is an alkyl group; or ##STR6## where R.sub.2 is an alkyl group; ##STR7## being a trans-1,4-disubstituted cyclohexane ring and ##STR8## a 1,4-disubstituted bicyclo(2,2,2)octane ring.

Abstract: A device for indicating windspeed and direction to a parachutist and comprising a datum element for plummetting to the ground, a status element having a parachute for floating to the ground, a cord linking the two elements, and different markers on each element.

Abstract: A method of electroluminescent panel manufacture in which a doped zinc chalcogenide phospher film--for example manganese doped zinc sulphide, is deposited upon an electrode bearing substrate in the presence of a hydrogen enriched atmosphere--for example a 90%:10% argon:hydrogen atmosphere. This is followed by rapid anneal treatment, the substrate being raised quickly to a temperature of 450.degree. C., or greater, and cooled rapidly. It is preferable that, prior to film deposition, the substrate is pretreated by baking in the hydrogen enriched atmosphere. An additional current density limiting film may be applied--a film of low resistance cermet material--for example silica/nickel 20% Ni in SiO.sub.2, or a film of amorphous silicon.

Abstract: An alternating bias is applied to a modified photoconductive detector and photosignal extracted from each detector element. This extraction may be performed using an integrator to produce a dc signal output, or alternatively by using a high-pass filter or phase-sensitive detector to extract a photosignal at an harmonic of the bias frequency. The detector used is provided with elements that have a responsivity that is a different function of bias amplitude for each polarity. The detector element may be shaped with variation in width or depth, to produce this differential responsivity. Alternatively element bias contacts may be of different width to produce field gradient and differential responsivity. It is advantageous to obscure a part of each element area by including an opaque mask.

Abstract: An imaging system for obtaining information within the diffraction limit comprises an illuminating source of radiation, e.g. a laser. A lens system focuses radiation from a small area of an object onto a detector array in an image plane. The detectors measure the amplitude of the received radiation giving a matrix of information. This matrix is then inverted by a computer to reconstruct the image for observation on a cathode ray tube. The object is scanned by scanning the radiation or stepping the object.

Abstract: A casting process is described, the process embodying the use of cores made from material comprising dicalcium silicate. Dicalcium silicate undergoes various phase changes during heating and cooling one of which, the .beta. to .gamma. transformation, is accompanied by a large volume increase. By using this feature casting cores may be produced which disintegrate during cooling of the solidified metal.

Abstract: Affinity chromatography media are prepared by reacting mono or di-chloro triazine dyes with a solid support matrix containing free hydroxy or amino groups in the presence of an alkali metal hydroxide and an alkali metal salt. In the absence of cyanogen bromide activation, the linkage to the support is entirely via the triazine ring giving high and specific protein-binding capacity. Suitable support matrices include polymers and copolymers of agarose, dextrose, dextran and acrylamide with agarose being particularly preferred. Dye binding levels are much higher than those obtained in the presence of carbonates or bicarbonates.Mono-chlorotriazinyl dyes are bound at a pH which is preferably above 9.5. The reaction time is about 40-60 hours at room temperature, however this may be reduced if the reaction temperature is increased. Dichlorotriazinyl dyes are bound at pH 8 to 12.5 in a few hours at room temperature.

Abstract: Liquid crystal compositions are described which comprise a mixture of compounds and which includes at least one additive compound characterized in that the composition includes one or more additive compounds of Formula I as follows: ##STR1## wherein R.sub.1 represents an alkyl group, R.sub.2 represents an alkyl or alkoxy group or hydrogen and ##STR2## represents a 1,4-disubstituted bicyclo(2,2,2)octane ring. The preparation and properties of novel compounds of Formula I are also described. These liquid crystal compositions are useful in display devices such as digital calculators and word displays.

Abstract: A time clock modem transmitter comprises a pseudo-random number generator (PNG) which produces a time-spaced sequence of pseudo-random numbers such that each number uniquely represents the time of day. A transmitter PNG(11) capable of producing a polynomial sequence longer than 24 hours is reset every 24 hours by a transmitter reference clock (4). A receiver clock modem includes a receiver PNG(26) having the same polynomial characteristics as the transmitter PNG(11). A received signal number is fed into the receiver PNG and the PNG is then started. The output from the receiver PNG and the received signal are then compared to ensure correct synchronization of the receiver clock modem. A detector is provided which is responsive to the random number representing 2400 hours such that it produces a resetting output pulse at 2400 hours to reset a receiver reference clock.

Abstract: A liquid crystal ester has a structure: ##STR1## where X and Y are fluorine or hydrogen at least one being hydrogen, and Z is either:(a) ##STR2## where R.sub.2 is alkyl, alkoxy, alkylcarbonyloxy or alkoxycarbonyloxy(b) ##STR3## where R.sub.3 is an alkyl group. The ester may be prepared by a conventional esterification from the corresponding phenol ##STR4## and the corresponding acid chloride Z--COCl. The ester may be used in mixtures with other liquid crystal compounds for use in known electro-optic devices.

Abstract: The invention provides a silencer for high velocity gas flow which includes a flow passage 2 and a domed, perforated plate 1 which terminates the flow passage, wherein the perforated portions 9 of the plate are distributed over the plate so as to direct gas from the passage as plurality of divergent jets 7 whereby noise is produced with a frequency at maximum intensity in a range of the audible spectrum at which human auditory perception is relatively insensitive. Such a silencer may be used to reduce the perceived noise emitted by a gas turbine engine when for reasons of engine handling and response excess air bled from the compressor stages.