Abstract: Compounds suitable for use as constituents of ferroelectric smectic liquid crystal compositions, which are ester of formula (I), where R.sub.2 and R.sub.3 together represent the residue of an alicyclic hydrocarbon ring system where *C is an asymmetric carbon atom and X is a chain of up to three linked aromatic or alicyclic six-membered organic cyclic groups, laterally and/or terminally substituted. Preferred compounds have a formula (II), where R.sub.1 is alkyl or alkoxy, A, B, and D are phenyl, fluoro or chloro substituted phenyl or cyclohexyl, n is 0 or 1, Y is a bond or CH.sub.2 CH.sub.2 if n is 0, or a bond CH.sub.2 CH.sub.2 COO or COO if n is 1. Preferred groups C(CN)R.sub.2 R.sub.3 are formula (III) and (IV).

Abstract: A continuous process for producing nitratoalkyl-substituted cyclic ethers which consists of (a) cocurrently mixing a stream of N.sub.2 O.sub.5 and a stream of a hydroxyalkyl-substituted cyclic ether each dissolved in an inert organic solvent, followed by (b) rapidly separating the nitric acid and nitratoalkyl coproducts before they can react together to rupture the ether ring. Step (b) is conveniently performed by quenching the product stream within approximately 15 seconds of its formation, in a basic aqueous solution into which the nitric acid is transferred from the organic phase and is neutralized. Examples of products which may be prepared by this process are nitratoalkyl-substituted oxiranes and oxetanes.

Abstract: A diode circuit in which the flicker noise generated by the diode is reduced comprises a diode (D1) connected in series with a resistor (R2) having a by-pass capacitor (C1) in parallel therewith. In one embodiment the side of the diode remote from this resistor (R2) is connected to one input of a DC differential inverting amplifier (A1) via a low pass filter (L1, C2). The amplifier's output is negatively fed back to the junction of the diode (D1) and the resistor (R2) so that the latter forms the amplifier load. A control voltage is applied to the other input of the amplifier of such value as to produce the required diode bias. The basic diode circuit can be extended to perform functions such as amplitude limiting, frequency control and modulation.

Abstract: A fuselage, particularly of a guided missile, having a rotatable nose body carrying a pair of similar strakes symmetricaly disposed about the body and for anchoring incidence generated vortices thereon.

Abstract: An arrangement for transferring items to or from e.g. a glovebox, in a closed moveable container, the glovebox port has a door having a non-rotatable outer portion (12) and a rotatable inner portion (13). The container (2) has a lid having a non-rotatable outer portion (3) and a rotatable inner portion (4), the outer portion (3) having a thin lip (10). The port has a thin lip (19) which can be aligned with the lip (10) of the lid. The outer portion (12) of the door retains a peripheral sealing ring (17) and the rim of the container retains a similar ring (8) which can sandwich and bridge the two lips. The container (2) is attached to the port by a rotatable locking ring (27).

Abstract: The invention is a method of producing oriented, essentially perfect colloidal crystals by subjecting a suspension of colloidal spheres, which is contained betwen two narrowly spaced substantially parallel surfaces, to oscillating motion. This motion must have a frequency greater than the Brownian motion of the spheres and an amplitude approximately equal to the thickness of the surface's separation. This method is suitable for monosized spheres of radii between about 0.1 and 1 micron. The suspension of colloidal spheres must have a volume fraction greater than 0.49. This method produces colloidal crystals with a uniform face centered cubic structure, which are suitable for use as notch optical filters, high strength ceramics, or thin film dielectric materials.

Abstract: A method of preparing a nitrate ester of an epoxy alcohol, which consists of reacting an epoxy alcohol with N.sub.2 O.sub.5 in an inert solvent at a temperature of -10.degree. C. to -40.degree. C., followed by quenching the reaction mixture in aqueous solution. Quenching separates the nitric acid and nitrate ester coproducts into aqueous and organic phases respectively to prevent subsequent reaction between the two. Reaction between the nitric acid coproduct and epoxy alcohol reagent to produce acyclic contaminants is supressed by adding the epoxy alcohol to excess N.sub.2 O.sub.5, thereby rapidly converting available alcohol to nitrate ester.

Abstract: Novel cyanohydrin derivatives of general formula (I) wherein R.sup.1 is hydrogen, alkyl, alkoxy, perfluoroalkyl or perfluoroalkoxy, R.sup.2 is alkyl, r is 1 to 10, n and m are 0 or 1, provided if both n and m are 0 then X is (II) or (III), where (F) indicates one or more optional fluorines, p is 0 or 1, Z is a single bond if p is 0 and COO if p is 1; and if one or both of n or m are 1 then X is (IV), where each ring A, B and C is phenyl, fluoro- or chloro-phenyl, cyclohexyl, pyrimidyl, pyridyl, or dioxanyl, A, B and C are single bonds or linking groups, and (a+b+c) is 2 or 3. Liquid crystal materials containing these compounds are also described.

Abstract: A method of separating N.sub.2 O.sub.5 from its solution in nitric acid which comprises the steps of: (a) preparing, by the electrochemical oxidation of N.sub.2 O.sub.4 in nitric acid, a nitric acid solution at a temperature of at least 10.degree. C. containing at least 45 wt. % of dissolved (N.sub.2 O.sub.4 +N.sub.2 O.sub.5) and having a dissolved N.sub.2 O.sub.5 :nitric acid ratio by weight of at least 1:3, and (b) cooling the acid solution to less than 8.degree. C. until an N.sub.2 O.sub.5 solvate precipitates from solution. The main advantage of the invention is that it enables electrically-efficient electrochemical methods to be employed in the production of the acid solution from which the solute is recovered.

Abstract: Articles of titanium based materials are protected against alpha case formation such as results from exposure to air at high temperatures coating with a nickel-chromium based alloy. The coating may be deposited by ion plating, sputter plating or sputter ion plating these methods being preferred for avoidance of surface contamination. A preferred nickel to chromium ratio (by weight) is 18:1 to 1.5:1. Specific coating compositions are: a) Nimonic 75 (trade name) a 20 percent chromium 80 percent nickel (by weight) based alloy; and b) Ni-35Cr-8Al-8Si (by weight).

Abstract: A process is provided for the electrochemical generation of N.sub.2 O.sub.5 in HNO.sub.3, whereby a solution of N.sub.2 O.sub.4 in HNO.sub.3 is electrolyzed. An electrolytic cell for the electrolysis is also provided, having substantially parallel electrodes in electrode compartments separated by a cell membrane. The anode is of Pt, Nb, Nb/Ta 40:60 alloy with a Pt coating. The cathode is Pt, stainless steel, Nb, Nb/Ta 40:60 alloy. The cell membrane is preferably a perfluorinated cationic exchange membrane. In use N.sub.2 O.sub.5 forms in the anolyte and N.sub.2 O.sub.4 increases in the catholyte. A suitable design of cell and its use in a single- or multi-stage electrolysis process is also described.

Abstract: A ferromagnetic material having the formula MGa.sub.2-x As.sub.x where 0.15.ltoreq.x.ltoreq.0.99 and M represents one of Fe.sub.3, Fe.sub.3 partially substituted by manganese or Fe.sub.3 partially substituted by cobalt.

Abstract: A system for detecting and classifying vehicles, moving in the vicinity of a seismic detector, includes a time threshold circuit and, complementary to this circuit, two parallel amplitude detector circuits. One detector circuit utilizes amplitude thresholding to distinguish the seismic vibrations characteristic of moving vehicles, from other seismic vibrations. The other detector circuit utilizes amplitude thresholding to distinguish the seismic vibrations characteristic of a particular kind of moving vehicle (e.g. a tracked vehicle), from other seismic vibrations. The results of these two amplitude detector circuits and of the time threshold circuit are utilized by an indicator circuit and an indication of detected vehicle kind (e.g. tracked or wheeled) provided. Indication may be relayed, to a remote observer, by radio transmission.

Abstract: A radiation sensor for centimeter, millimeter or sub-millimeter waveband receiption, comprising a metal antenna located close to a supporting dielectric body of intermediate to high dielectric constant value and having a mixer located in between and connected to the limbs of the antenna. The supporting body may itself be of semiconductor material, or if of insulating dielectric material, semiconductor material may be incorporated adjacent the antenna; and the mixer components, diodes, integrated in the semiconductor material. Antennae, as above, may be arranged in close-packed array, and the supporting body configured as, or as part of, a lens.

Abstract: An electrical switch for switching large currents in a low voltage circuit consists of two opposing terminals (32) connected to conducting rails (20) of an electromagnetic projectile launcher (10), each terminal having two conducting arms (32A, 32B) which enclose the breech chamber (114) of the launcher. Conducting contacts (66A, 66B) bridging across the opposing arms of the terminals are rapidly lifted to open the switch when the contacts are exposed to propellant gas pressure exerted on a projectile armature (22) slideable within the chamber. Electromagnetic forces of repulsion, which act upon whichever contact is the latter of the two to lift off the terminals, assist simultaneity of current pathway severance across both arms, thereby suppressing arcing at switch opening.

Abstract: An apparatus and method which provides a measure of the asymmetry as well as the size of individual fluid borne particles. Laser-light scattering techniques are employed to obtain data on the particles, which is then compared to data on known particle shapes to ascribe an asymmetry factor to the particles.

Abstract: A torch igniter intended particularly for gas turbine engine applications comprises an integral assembly of a flame lighter and a fuel atomizer of the pre-filming air blast type. The fuel atomizer is configured so as to encircle the tip of the flame lighter and this atomizer comprises fuel and air inlets, a fuel/air passage defined between a body portion of the flame lighter and a sleeve this fuel air passage extending from the inlets to an exit mouth around the electrodes at the tip of the flame lighter, and an atomizer lip at the mouth of the fuel/air passage. A secondary passage can be included to aid in atomization of the fuel and in direction of the spray of atomized fuel this secondary passage having an exit annulus encircling the mouth of the fuel/air passage. A further passage can be included which is exposed to heat exchange with exterior air to pre-cool compressor delivery air before supply to the atomizer.

Abstract: An electro-optic waveguide device (10) comprises an assembly of waveguides (30) connected to a common light input region (41) and forming a common far field diffraction pattern (44). The device (10) comprises an n.sup.+ GaAs substrate (14) bearing a waveguide lower cladding layer (16) of n.sup.+ Ga.sub.0.9 Al.sub.0.1 As, which is in turn surmounted by a waveguide core layer (18) of n.sup.- GaAs. The layer (18) has grooves (20) defining the waveguides (30), each of which has a respective Schottky contact (32). Each contact (32) is biased negative with respect to the substrate (14), which reverse biases the respective Schottky diode waveguide structure. The waveguide core layer (18) has electro-optic properties, and its refractive index varies with electric field. The phase of light emerging from each waveguide is therefore independently variable by means of its applied bias voltage.

Abstract: A fluoride ion sensitive material suitable for use as the active component in a fluoride ion sensitive electrode comprises a sintered mixture comprising of up to 99.9 molar % of Lanthanum trifluoride and from 0.1 to 20 molar % Calcium difluoride formed from a body that has been pressed at 10.sup.7 Pa or more and then sintered in a inert atmosphere at 900.degree. C. or more.

Abstract: A photodetector (10) of the non-equilibrium kind incorporates three successively disposed sections (14, 16, 18) of like layer construction. Each of the sections (e.g. 14) contains three layers (14A, 14B, 14C) of semiconductor materials of the Cd.sub.x Hg.sub.1-x Te alloy system (CMT). The central layer (14B) of each section (14) is of narrow bandgap CMT, i.e. x=0.19 or 0.265 for absorption at 3-5 .mu.m or 8-12 .mu.m, and has very low doping (10.sup.15 cm.sup.-3) providing intrinsic conductivity. It is 1.5 .mu.m thick, less than one third of an optical absorption length. The outer layers of each section (14A, 14B) are 10 .mu.m thick and are of wide bandgap CMT, i.e. x=0.4. They have respective n and p type dopant concentrations of 3.times.10.sup.16 cm.sup.-3 providing extrinsic conductivity. Each central layer (14B) is therefore bounded by an excluding contact (14AB) and an extracting contact (14BC), which depress its carrier concentration to an extrinsic level under the action of electrical bias.