Abstract: This invention relates to paper machine clothing and has particular reference to paper machine clothing suitable for use in the forming, presing and drying sections of a papermakng machine and comprises a monofilament and/or staple fibre in which themonofilament or staple fibre comprises a polyamide material which has been subjected to a treatment with an aqueous solution of aldehyde in the presence of a catalyst to effect partial cross-linking of the polyamide to provide a gel content thereof within the range of 0.1-75%.

Abstract: A gas-liquid mixing system employs an impeller/draft tube assembly submerged in liquid. Hollow eductor tubes affixed to the impeller drive shaft are used to flow gas from an overhead gas space to the liquid in the vicinity of the assembly. The positioning and size of the eductor tubes are such as to maximize the desired gas-liquid mixing and reaction rate.

Abstract: The present invention relates to a felt for use in papermaking machines showing enhanced resistance to degradation in the presence of peroxide which felt comprises a woven base and a sheet contracting layer attached thereto characterized in that at least one of said layer and said woven base comprises fibers of polyamide 12, 12 found by extrusion of a melt of polyamide 12, 12 having intrinsic viscosity of not less than 0.65 dl/gram.

Abstract: This invention relates in general to the formation of thick films having a biaxial molecular orientation. Such films are prepared in accordance with the present invention from rod-like extended chain aromatic-heterocyclic ordered polymers. Such films have high tensile strength, modulus, and environmental resistance characteristics. A preferred ordered polymer for use in the present invention is poly (para--phenylenebenzo bisthiazole), (PBT), a compound having the structure: ##STR1## The present invention is also directed to methods and apparatus suitable for producing biaxially oriented films, coatings, and like materials from ordered polymers, preferably PBT.

Abstract: This invention relates in general to the formation of multiaxially (e.g., biaxially) oriented films from high molecular weight lyotropic or thermotropic polymers (homopolymers, copolymers, and the like), wherein due to the processing conditions employed, the films have a controlled molecular orientation. The films of the present invention are preferably prepared from rod-like extended-chain, aromatic- heterocyclic polymers. These polymers generally fall into two classes; first, those that are modified in solution form, i.e., lyotropic liquid crystalline polymers; and second, those that are modSTATEMENT OF GOVERNMENT INTERESTFunding for the present invention was obtained from the Government of the United States by virtue of Contract Nos. F33615-83-C-5120 and N00164-87-C-0050, from the Departments of the Air Force and the Navy, respectively. Thus, the Government of the United States has certain rights in and to the invention claimed herein.

Abstract: This invention relates in general to the formation of thick films having a biaxial molecular orientation. Such films are prepared in accordance with the present invention from rod-like extended chain aromatic-heterocyclic ordered polymers. Such films have high tensile strength, modulus, and environmental resistance characteristics.A preferred ordered polymer for use in the present invention is poly (para - phenylenebenzo bisthiazole), (PBT), a compound having the structure: ##STR1## The present invention is also directed to methods and apparatus suitable for producing biaxially oriented films, coatings, and like materials from ordered polymers, preferably PBT.

Abstract: The invention relates to an improved felt for a paper making machine having a batt formed from polyamide-12 needled to a woven base. The polyamide 12 batt may contain an antioxidant. The felts in accordance with the invention show much improved longevity and resistance to "flattening" in service.

Abstract: The present invention relates to a method and apparatus for the generation of essentially spherical frozen droplets of a liquid biological or organic-comprising composition. The liquid composition if fed under positive pressure through a nozzle in a manner which provides a continuous stream of the liquid composition exiting the nozzle; the continuous stream travels through a gas or vapor for a distance sufficient to cause the continuous stream to break apart, forming droplets ranging in size from about 0.6 mm to about 5 mm; the liquid composition droplets are then contacted with a cryogenic liquid capable of freezing the droplets into a solid phase; the frozen droplets are concentrated into a portion of the contacting cryogenic liquid from which they are subsequently separated.

Abstract: A method and apparatus for rapidly cooling optical fiber comprising passing optical fiber through an enclosure having a flat black internal surface, the walls of said enclosure having symmetrically oriented perforations or other symmetrically oriented means of passing cryogenic gas through the walls to contact optical fiber within the enclosure, the enclosure surrounded by a gas plenum to which gas is supplied to facilitate the symmetrical passage of cryogenic gas through the walls, whereby the cryogenic gas symmetrically contacts and cools the optical fiber and also serves to cool the walls of the enclosure.

Abstract: A current amplifier is provided having a single control amplifier and a plurality of output stages. The desired output stage is digitally selected. The ratios of the output stage currents may be selected during the metalization process. A single capacitor compensates for all output stages regardless of which output stage is selected.

Abstract: In a method for cooling a process gas stream with a liquid cryogen, said stream being recycled through a pipe in a closed system comprising a reactor containing at least one pipe wherein, at the initiation of the instant method:(i) the flowrate of the stream is in the range of about 10,000 scfm to about 350,000 scfm;(ii) the temperature of the stream is in the range of about 75 degrees F. to about 450 degrees F.; and(iii) the pressure of the system is in the range of about 150 psig to about 1000 psig;and wherein, at any time during the effectuation of the instant method:(iv) the temperature differential between any two points in the pipe separated by at least about eight times the nominal pipe diameter is no greater than about 200 degrees F.; and(v) the minimum temperature of the pipe is at least about minus 20 degrees F.

Abstract: In a process for cooling and fluidizing a bed of particles by passing a cryogen through the bed, said bed being first cooled to a desired operating temperature, the improvement comprising:(a) admixing a liquid cryogen and an inert gas, said gas being at ambient temperature, at a point external, but proximate, to the bed to provide a mixture of liquid cryogen and gas at a temperature sufficiently low to maintain the bed at about the desired operating temperature;(b) introducing the mixture from step (a) into at least two heat transfer coils connected in parallel and located in the bed whereby the desired operating temperature is imparted to the bed, and the liquid cryogen in the mixture vaporizes; and(c) removing the mixture of vaporized liquid cryogen and gas formed in step (b) from the coils and introducing the mixture into the bed to fluidize the bed.

Abstract: In a process for operating a fluidized bed, wherein the bed particles have a Reynolds number of less than 20, at a predetermined cryogenic temperature comprising (i) bringing a cryogenic fluid into indirect contact with the bed; (ii) permitting the fluid to vaporize at the area of indirect contact whereby the bed is cooled; and (iii) utilizing the vapor from step (ii) to fluidize, and further cool, the bed, said cooling in steps (ii) or (iii) being from ambient temperature to the predetermined cryogenic temperature,the improvement comprising changing, continuously or stepwise, the minimum fluidizing mass flow of vapor as the temperature of the bed changes in accordance with a specified equation.

Abstract: Sheet materials for cardiovascular and other prosthetic implants are fabricated of synthetic elastomers. These materials are characterized by molecular configurations that produce a nonlinear tensile modulus characteristic similar in shape to that of natural tissue. Selected elastomers, when formed as sheet material of appropriate geometrical configuration, promote the formation of natural tissue thereon which is appropriate for the mechanical characteristics desired.

Abstract: A process for delivering a liquid cryogen to a use point in an essentially liquid phase at an about constant flow rate in the range of about 1 to about 40 pounds per hour, said use point having a variable internal pressure drop, comprising the following steps:(i) providing said liquid cryogen at a line pressure in the range of about 4 to about 10 times the maximum use point operating pressure;(ii) subcooling the liquid cryogen of step (i) to an equilibrium pressure of no greater than about one atmosphere while maintaining said ine pressure;(iii) passing the liquid cryogen of step (ii) through a device having a flow coefficient in the range of about 0.0002 to about 0.005 while cooling said device externally to a temperature, which will maintain the liquid cryogen in essentially the liquid phase; and(iv) passing the liquid cryogen exiting the device in step (iii) through an insulated tube having an internal diameter in the range of about 0.020 inch to about 0.200 inch to the use point.

Abstract: A frame system for heart valve prosthesis. A first frame has at least three generally parallel legs each comprising a pair of rod portions connected at one end and diverging at the other end as lobes respectively connecting with rod portions of others of said legs. The lobes form an aperture therebetween and the legs are adapted to receive the margin of a valve leaflet between the rod portions thereof. Thus, the leaflet may be secured to two adjacent legs and the interconnecting lobe so as to have a free edge extending between said adjacent legs. A second frame is adapted to nest with the first frame and comprises a rod formed to be substantially congruent with the interconnecting lobes, whereby the leaflets may be secured to and between the frames.

Abstract: Apparatus and process for delivering small controlled quantities of a liquid cryogen to a use point in an intermittent manner comprising an off-period in which no liquid is desired at the use point and followed by an on-period in which liquid is delivered to the use point essentially free of vapor.

Abstract: A control system for optimizing the flow of a cryogenic refrigerant into the precooler and mill of a cryopulverizing system including means responsive to a change in the discharge temperature in the mill for introducing refrigerant into the mill in direct proportion to such temperature change and means responsive to the change in discharge temperature in the mill for introducing refrigerant into the precooler at a linear rate proportional to the product of the material feed rate and the change in discharge temperature and inversely proportional to the residence time of the feed material in the precooler.

Abstract: A hollow filament separatory module utilizing an annulus of semi-permeable hollow filaments with open ends encased in a potting compound and a collection chamber communicating with said open ends adjacent the potting compound with access surface means formed in the potting compound wherein the open ends appear, said filaments having ends thereof encapsulated by the introduction of potting medium into the interfilament interstices under the urging of vibratory energy and thereafter creating said open ends by cutting of ends and potting medium at a time in the curring cycle of the potting compound prior to its final cure.

Abstract: A prosthesis for an inadequate or diseased heart valve, the prosthesis being formed of a porous fabric comprising multifilament synthetic yarns supported on a plural-lobed frame. The frame has generally parallel legs each comprising a pair of rod portions. The fabric is inserted between the rod portions of the legs to form flexible leaflets. Each leaflet consists essentially of a textile of filaments having a substantial number of open interstitial spaces in the range of 20 to 40 microns evenly distributed throughout the fabric. The resulting composite structures are free of thrombogenic complications.