Abstract: A fuel cell power system that includes multiple strings that each have multiple sub-stacks of fuel cells. Each sub-stack is electrically isolated from other sub-stacks and each sub-stack can be independently controlled by a DC control module on a printed circuit board. The DC control module of a sub-stack can regulate or shut off the output power of the sub-stack if the sub-stack becomes weak or fails. A sub-stack can be shut off while other sub-stacks in the system continue to operate. The output power of other sub-stacks can be increased to compensate for sub-stacks that are shut down.

Abstract: A phosphonate ester (vinyl phosphonic acid reacted with equimolar diol) will cure on command (e.g. exposure to light) in the presence of an initiator. By adding inert filler, poly(vinyl phosphonic acid), ion-leachable glass powder and water, a command-curable dental cement with glass ionomer characteristics is obtained.

Abstract: A glass ionomer cement composition comprises poly(vinyl phosphonic acid) dissolved in its own mass of water; and (in treble the total mass of the solution) a powder, being glass or MgO or a cement. The powder has to be deactivated so that the setting reaction with the acid is not too fast, and this is achieved either by a raised Si:Al ratio or by heat-treating. The glass contains heavy ions such as La, Ba or Sr.

Abstract: Dental cement comprising (a) calcium or zinc oxide or hydroxide, (b) a substituted aromatic compound capable of forming a cement with (a), the calcium or zinc oxide or hydroxide of (a) being in stoichiometric excess over (b), and (c) dry poly(carboxylic acid), or a precursor thereof, or dry cation-crosslinkable polymeric acid containing on average 1 phosphonic acid group per 1 to 3 backbone carbon atoms. The cement has bacteriostatic properties, stimulates the formation of secondary dentine, forms an adhesive bond and can be used where pulp tissue is exposed.

Abstract: A glass ionomer cement composition comprises poly(vinyl phosphonic acid) dissolved in its own mass of water; and (in treble the total mass of the solution) a powder, being glass or MgO or a cermet. The powder has to be deactivated so that the setting reaction with the acid is not too fast, and this is achieved either by a raised Si:Al ratio or by heat-treating.

Abstract: A metallic container for beverage is protected from its contents by electrodeposited zinc, which is anodized in alkali then anodically reacted with weak poly(acrylic acid) and finally cured at 85.degree. C. at 100% relative humidity.

Abstract: The method of fabrication of a monolithic silicon membrane structure in which the membrane and its supporting framework are constructed from a single ultra thick body of silicon. The fabrication sequence includes the steps of providing a doped membrane layer on the silicon body, forming an apertured mask on the silicon body, and removal of an unwanted silicon region by mechanical grinding and chemical etching to provide a well opening in the silicon body terminating in the doped membrane.

Abstract: A metallic container for beverage is protected from its contents by electrodeposited zinc, which is anodized in alkali then anodically reacted with weak poly(acrylic acid) and finally cured at 85.degree. C. at 100% relative humidity.

Abstract: A sustained release device which comprises a source of at least one trace chemical element incorporated in a cement and releasable therefrom on contact with an aqueous medium.The trace chemical element is exemplified by selenium, cobalt and iodine and the cement is exemplified by a phosphate cement.

Abstract: A process for the preparation of a coherent protective layer on a substrate surface of a body, the substrate surface comprising elemental metal or an alloy thereof, which process comprises applying to the substrate surface an aqueous solution of a partially neutralised homo- or copolymer of a mono- or polybasic ethylenically unsaturated acid; and heat-curing the layer so formed at a temperature above 180.degree. C.

Abstract: A body having a substrate surface which comprises corrodible material and on which substrate surface is present a coherent protective layer of an anti-corrosion composition which comprises a solid matrix of electrical conductivity .gtoreq.10.sup.-6 mho cm.sup.-1 and formed by reaction between at least water-soluble Bronsted acid and at least one Lewis base in which matrix is incorporated an elemental metal, or an alloy thereof, the matrix and metal being effective in service as electrolyte and sacrificial anode, respectively.

Abstract: A hardenable composition which comprises (i) a poly(carboxylic acid) or precursor thereof (as herein defined); (ii) a particulate ion-leachable silicate, aluminosilicate or metal oxide reactable with (i) in the presence of water to set to a hardened composition; and (iii) a compound comprising at least one phosphorus-carbon or phosphorus-boron covalent bond, in an amount effective in service to extend the working time of the composition.

Abstract: A sustained release device which comprises a source of at least one trace chemical element incorporated in a cement and releasable therefrom on contact with an aqueous medium. A preferred cement is copper phosphate cement.

Abstract: A high precision, high throughput submicrometer workpiece positioning system, particularly useful as a workpiece positioning means in electron beam lithography tools. The positioning system increases mechanical stability by essentially eliminating mechanical hysteresis, which allows state of the art electron beam lithography systems to provide the repeatable, accurate and dense circuit patterns that modern semiconductor trends demand.The positioning system in preferred form comprises a movable positioning table, a workpiece supporting superstructure which is elastically joined to the movable positioning table by three geometrically distinct kinematic support means and a two-stage coupling means which mounts a workpiece (i.e., semiconductor mask or wafer) to the workpiece supporting superstructure. A laser interferometer locating-positioning system is utilized to position the workpiece. The interferometer mirrors are integral with the workpiece supporting superstructure.

Abstract: A poly(carboxylate) cement pack comprising a water soluble poly(carboxylic acid) having a relative viscosity of from 1.05 to 2.00, a chelating agent and a cement powder which will react with the poly(carboxylic acid) in the presence of the chelating agent and water to give a plastic mass which rapidly hardens to form a poly(carboxylate) cement.

Abstract: A large lithographic pattern is written as quickly as possible by writing successive subpatterns in a vector scan mode of operation without any interruption between successive subpatterns. This is made possible by arranging the subpatterns so that they are adjacent to each other and are preferably overlapping and by gradually moving the workpiece with respect to the writing field so as to always keep the subpattern being written within the writing field of the beam. The speed and direction of the workpiece movement (relative to the writing field) is not predetermined for all patterns but is controlled instead by the pattern being written. A sparsely written pattern or portion of a pattern is accompanied by a more rapid table movement than what accompanies a densely written pattern or portion of a pattern. This is made possible by embedding pattern determined workpiece movement commands within the pattern defining data.

Abstract: An electron beam fabricated mask used in the production of integrated circuits is tested by a method that includes the steps of forming a print of the mask and then inspecting the print by writing the same electron beam pattern or complement thereof on the print and detecting pattern coincidence and non-coincidence with a vector scan system.

Abstract: Compositions which are hardenable in the presence of water to form a poly(carboxylate) cement contain a metal salt which accelerates the setting of the composition.

Abstract: A cement-forming liquid suitable for use as a component of a poly(carboxylate) cement comprises an aqueous solution of a copolymer of acrylic acid, the copolymer having an average molecular weight of less than 20,000, and the solution having a viscosity of less than 50 poise.

Abstract: A poly(carboxylate) cement pack comprising a water soluble poly(carboxylic acid) having a relative viscosity of from 1.05 to 2.00, a chelating agent and a cement powder which will react with the poly(carboxylic acid) in the presence of the chelating agent and water to give a plastic mass which rapidly hardens to form a poly(carboxylate) cement.