The invention discloses materials that adsorb readily to the surfaces of body tissues in situ and provide a steric barrier between such tissues, so that tissue adhesions, which typically form following surgical procedures, are minimized. These materials contain a polymer of hydrophilic molecules such as polyethylene glycol (PEG) bound to a polymer that spontaneously adsorbs to biological tissue such as phenylboronic acid (PBA). The PEG-PBA co-polymer can be formed in a variety of geometries. The materials can also be used to coat prosthetics and other implants.

The present invention relates to methods and polymeric compositions for preventing the formation of tissue adhesions following surgical procedures or injury.
Many pathological conditions result from the adhesion of proteins or cells to extracellular matrix, membranes, or other surfaces in the body. For example, damage to tissue surfaces after peritoneal surgery can result in formation of fibrinous attachments between tissues. G. dizerega, Fertility and Sterility 61:219-235 (1994); G. Holtz, Fertility and Sterility 41:497-507 (1984). These adhesions can have severe consequences including pain, bowel obstruction, and infertility. Adhesion can also occur as a result of cataract surgery. Residual lens epithelial cells migrate onto the posterior lens capsule, resulting in formation of a secondary cataract, referred to as posterior capsule opacification, and subsequent reduction in vision. D. Apple et al., Survey of Ophthalmology 37:73-116 (1992).
These conditions result from disruption of the naturally occurring surface of a biological tissue through surgical manipulation or external injury, followed by direct contact of one such disrupted biological surface with another biological surface, and then formation of a cellular adhesion that connects the adjacent tissues. Adhesions are scar tissue bridges that often connect to opposing organs, for example, restricting organ movement and function as well as causing pain.
One approach to prevention of adhesions has involved using a physical barrier that isolates the biological surfaces from each other. Attempts to prevent surface to surface contact of tissues have met with varying levels of success. In some cases, the materials did not remain in intimate contact with the treated biological surface for a sufficient period of time. In other cases, application of the barrier materials required extensive surgical manipulation in order to cover inaccessible tissue surfaces.
Most previous work in preventing adhesions has been in the field of gynecological surgery. Solid, liquid, and gel materials have been used. Solid treatments presumably work by providing a barrier between the damaged surface and other cells. The most popular of these materials are oxidized regenerated cellulose and expanded polytetrafluoroethylene, but use of these barriers has resulted in questionable efficacy, due to the requirement for extensive surgical manipulation, sometimes including additional surgery, nonadherence of the barrier to the surface, and immune response.
Liquid materials have included high molecular weight dextran solutions, hyaluronic acid, in liquid or gel form, and Ringer""s lactate. These materials may work by preventing tissue damage in the first place and/or by xe2x80x9cfloatingxe2x80x9d the tissues, but the materials can make surgical manipulation difficult and all of the materials have shown questionable efficacy.
Gel materials have included fibrin glues, a triblock copolymer of polyethylene glycol (PEG) and polypropylene glycol (PPG) which gels at physiological temperatures, and a PEG-co-lactic acid (PEG-PLA) hydrogel. U.S. Pat. Nos. 5,410,016, 5,626,863, and 5,567,435, to Hubbell et al., disclose PEG-PLA hydrogels useful for adhesion prevention. These treatments presumably work by forming a barrier over the injured surface. The fibrin glue has not been tested on lysed adhesions and it may induce inflammatory response. P. De Iaco et al., Fertility and Sterility 62:400-404 (1994); L. Adamyan et al., International Journal of Fertility 36:76-88 (1991). The triblock copolymer may be cleared from the wound site too quickly because it does not adhere specifically to surfaces. V. Montgomery Rice et al., Fertility and Sterility 59:901-906 (1993); A. Steinleitner et al., Fertility and Sterility 57:305-308 (1992). Application of the PEG-PLA hydrogel requires access to and specific treatment of each surface involved, as well as UV irradiation for the gel to form. J. West et al., Biomaterials 16:1153-1156 (1995).
Research on the prevention of posterior capsule opacification by blocking adhesion of epithelial cells to the posterior capsule has focused on causing firm contact between an implanted intraocular lens and the posterior capsule, presumably mechanically blocking the migration of cells into the visual axis of the posterior capsule. D. Apple et al., Survey of Ophthalmology 37:73-116 (1992); C. Ohadi et al., Current Opinion in Ophthalmology 2:46-52 (1991). The mechanism of this technique has yet to be confirmed, and clinical results vary.
Elbert has investigated self assembling treatments which sterically protect the underlying surfaces to allegedly prevent adhesions. D. L. Elbert et al., Chemistry and Biology 5:177-183 (1998). Elbert used copolymers containing PEG and lysine, having a comb geometry of a poly(lysine) backbone with PEG sidechains or a dendrimer geometry of PEG attached to a lysine dendrimer. The cationic copolymers may adsorb to many biological surfaces, presumably due to electrostatic interactions, while the PEG molecules presumably sterically hinder the approach of proteins and cells to the surfaces. Other research in the area has included using PEG to sterically protect surfaces by covalently adding PEG to the surface (S. Dunn et al., Pharmaceutical Research 11:1016-1022 (1994)), entrapping PEG in the surface (N. Desai et al., Biomaterials 13:505-510 (1992)), applying PEG to the surface within a gel (A. Steinleitner et al., Fertility and Sterility 57:305-308 (1992); J. West et al., Biomaterials 16:1153-1156 (1995)), PEG copolymers to surfaces by adding cationic moieties to the PEG (D. L. Elbert et al., Chemistry and Biology 5:177-183 (1998)).
A biocompatible material that would prevent surface to surface contact by spontaneously adhering directly to a biological surface, in sufficient quantities to protect the surface, would provide a great advantage over all of the aforementioned treatments. The material would also present a cell and protein resistant outer layer that would minimize interactions with other surfaces during healing.
It is therefore an object of the present invention to provide polymeric materials that can be applied to tissues, in a very short time period, to protect the tissues from tissue to tissue interactions, such as adhesion.
It is a further object of the present invention to provide polymeric materials which are biocompatible and resistant to degradation for a specific time period.
It is a further object of the present invention to provide methods for making and using compositions for inhibiting tissue to tissue contact and adhesion within the body.
Methods and compositions are provided that form a self assembling layer on biological surfaces. The materials prevent adhesion via steric hindrance and inhibit direct contact between adjacent tissues. The materials are easy to apply to the tissue surface and exhibit lasting intimate contact with the tissue surface. These materials are copolymers of a polymer including boronate groups such as phenylboronic acid, which adsorb onto biological surfaces, and a polymer which is nonadsorbing, and adhesion resistant, such as polyethylene glycol, which interferes sterically with surface contact between tissues. The copolymers spontaneously adsorb to many biological surfaces containing acid or hydroxyl groups and remain for a finite period of time, preferably a matter of days, to sterically protect the surface while it heals.
The compositions can be applied to isolated tissue or to tissue during surgery or by means of a catheter or other less invasive device, for example during angioplasty or atherosclerosis surgery. The compositions are useful for blocking adhesion and immune recognition and thereby aid in the prevention of postoperative adhesions, protection of injured blood vessels from thrombosis and intimal thickening relating to restenosis, and decrease the extent of metastasis of tumor cells. The materials can be used as barriers to prevent the interaction of one cell or tissue with another cell or tissue, and as carriers for bioactive species. A wide variety of biological and nonbiological surfaces, with different geometries, can also be coated with these polymeric materials.
Compositions for coating surfaces to minimize or prevent tissue to tissue contact and tissue adhesion, and methods of preparation and use thereof, are disclosed. The compositions can be used, for example, to coat tissue or other surfaces to alter cell or tissue interaction with a surface contacting the cell or tissue. The compositions can also be used to deliver therapeutic, prophylactic, or diagnostic substances or to encapsulate cells. Another use for the compositions is to minimize or prevent undesirable cell proliferation, decrease the risk of thrombosis, and decrease inflammation.
As defined herein, xe2x80x9ctissuexe2x80x9d includes tissues removed from the body and tissues present in the body, and also includes cells and cell aggregates. This term also refers to treated tissue, such as tissue heart valves, blood vessels and membranes, where the tissue is no longer living and has been chemically fixed, or a cryopreserved blood vessel or other tissue.
The following definitions apply to the copolymers described herein. Block copolymers are defined as copolymers in which a polymeric block is linked to one or more other polymeric blocks. This is distinguished from random copolymers, in which two or more monomeric units are linked in random order to form a copolymer. Brush copolymers (as in a bottle brush) are copolymers which have a backbone of one composition and bristles of another. These copolymers are also known as comb copolymers. The terms brush and comb are used interchangeably. Dendritic polymers, also known as dendrimers or starburst polymers, are polymers which include a core molecule which is sequentially reacted with monomers with three or more reactive groups, such that at each sequential coupling step, the number of reactive groups at the ends of the polymer increases, usually exponentially. A dendron is a subunit of a dendrimer, the structure resulting from sequential reactions starting with a core containing only reactive group. As used herein, molecular weight refers to weight average molecular weight, unless otherwise specified. As used herein, PEG is an abbreviation for polyethylene glycol, also known as polyethylene oxide or polyoxyethylene. The phrase xe2x80x9c(meth)acrylicxe2x80x9d refers to either acrylic or methacrylic groups.
A. Bifunctional Copolymers
These materials are copolymers which contain two functionalities. One functionality adheres the copolymer to one surface and another functionality presents an adhesion resistant outer layer to other tissue surfaces. The duration of protection provided by the copolymer is dependent on the rates of desorption and degradation of the copolymer.
The copolymers can have any of a number of geometries, including block copolymers where both segments are linear, dendritic copolymers where the adsorbing segment is dendritic, and, comb copolymers where the adsorbing segment is the copolymer backbone. The size, number of, and relative length of each segment can be varied, as required.
1. The Adherent Functionality
The adherent functionality of the copolymers is provided by a boronate group that can o a surface, such as through interaction with diols of surface polysaccharides. Useful boronates include phenylboronic acid (PBA), 2-carboxyethaneboronic acid, 1,2-dicarboxyethaneboronic acid, xcex2,xcex2xe2x80x2-dicarboxyethaneboronate, xcex2,xcex3-dicarboxypropaneboronate, 2-nitro- and 4-nitro-3-succinamidobenzene boronic acids, 3-nitro-4-(6-aminohexylamido)phenyl boronic acid, {4-[(hexamethylenetetramine)methyl]phenyl} boronic acid, 4-(N-methyl)carboxamidobenzene boronic acid, 2-{[(4-boronphenyl)methyl]-ethylammonio} ethyl and 2-{[(4-boronphenyl)methyl] diethylammonio}-ethyl groups, succinyl-3-aminophenylboronic acid, 6-aminocaproyl-3-aminophenylboronic acid, 3-(N-succinimidoxycarbonyl)aminophenylboronate, p-(xcfx89-aminoethyl)phenylboronate, p-vinylbenzeneboronate, N-(3-dihydroxyborylphenyl)succinamic acid, N-(4-nitro-3-dihydroxyborylphenyl)succinamic acid, O-dimethylaminomethylbenzeneboronic acid, 4-carboxybenzeneboronic acid, 4-(N-octyl)carboxamidobenzeneboronic acid, 3-nitro-4-carboxybenzeneboronic acid, 2-nitro-4-carboxybenzeneboronic acid, 4-bromophenylboronate, p-vinylbenzene boronate, 4-(xcfx89-aminoethyl)phenylboronate, catechol [2-(diethylamino)carbonyl, 4-bromomethyl]phenyl boronate, and 5-vinyl-2-dimethylaminomethylbenzeneboronic acid. These boronate containing groups differ in terms of pKa, spacer arms, or different coupling options associated with them.
In a preferred embodiment, the boronate group is provided by phenylboronic acid (PBA) which is known to form reversible conjugates with coplanar diols, such as closed ring carbohydrates and polyvinyl alcohol, as well as with acidic ligands such as dicarboxylic acids and xcex1-hydroxy carboxylic acids. PBA has a strong affinity to many biological surfaces, since the surfaces of cells and extracellular matrix are rich in proteoglycans and other carbohydrate moieties, as well as many acidic moieties. PBA also has been shown to form reversible complexes with glycoconjugates on endothelial cell membranes (T. Aoki et al., Journal of Biomaterials Science Polymer Edition 7:539-550 (1995)) and lymphocyte membranes (H. Miyazaki et al., Biochemical and Biophysical Research Communications 195:829-836 (1993)). The xe2x80x9cworking pHxe2x80x9d of the PBA moieties in each copolymer can be adjusted by placing amine groups in proximity to the PBA groups or by placing electron withdrawing groups within the PBA moiety itself. A PBA moiety with a nitro group in the ring and a succinamic acid functionality has been synthesized by Singhal et al., Journal of Chromatography 543:17-38 (1991), and could be coupled to amine groups using carbonyldiimidazole or N-hydroxysuccinimide. A PBA moiety that has an internal coordinate bond, making the boron tetrahedral, and that has a bromomethyl group that could be reacted with the thiol of cysteine was synthesized by X.-C. Liu et al., Journal of Chromatography A 687:61-69 (1994). A polymer precursor with a very low pKa, 5-vinyl-2-dimethylaminomethylbenzeneboronic acid that could be used in creating random copolymers containing PBA was synthesized by G. Wulff, Pure and Applied Chemistry 54:2093-2102 (1982).
2. The Adhesion Resisting Functionality
The nonadsorbing, adhesion resistant segment of the copolymer described herein consists of any of many water soluble polymers that are poorly cell adhesive. Neutral, highly hydrophilic polymers tend to be the best at resisting protein and cell adhesion. Suitable non tissue binding polymers include polyalkylene oxides, mixed polyalkylene oxides having a solubility of at least one gram/liter in aqueous solutions, water soluble polysaccharides, such as dextrans and agaroses, polyvinyl alcohol, poly-N-vinyl pyrrolidone, noncationic poly(meth)acrylates, such as poly(hydroxyethyl methacrylate), and combinations thereof. Anionic hydrophilic polymers such as polyacrylic acid can also be used, provided that the segment does not contain positive groups such as lysines, or else the polymer may precipitate with itself.
The adhesion resisting functionality is most preferably polyethylene glycol (PEG). PEG is very hydrophilic, associating with as many as 5.5 water molecules per ethylene oxide unit at 23xc2x0 C. P. Claesson et al., Journal of Colloid and Interface Science 117:366-374 (1986). PEG is also very flexible (W. B. Russel et al., Colloidal Dispersions (Cambridge University Press, New York, 1989)), and a small surface density of PEG can shield a large area. C. Pale-Grosdemange et al., Journal of the American Chemical Society 113:12-20 (1991). PEG elongates and rotates freely in water, excluding large amounts of space and resisting adsorption. There is much evidence that surfaces containing PEG are sterically protected. For example, surfaces containing PEG have been shown to greatly stabilize colloids, to resist protein adhesion much better than glucose or hydroxyl covered surfaces in vitro, to resist fibroblast adhesion in vitro, to induce less inflammation and fibrotic response than implants without PEG in vivo, and to reduce uptake of microspheres by liver cells in vivo.
B. Additional Polymeric Components
Additional polymeric components, domains, linking groups, and bioactive, prophylactic, or diagnostic materials can be added to this basic two domain structure. Examples of additional polymeric components for attachment of linking groups, and bioactive, prophylactic, or diagnostic materials include PEG, polyacrylic acid, poly-N-vinyl pyrrolidone, hyaluronic acid, and other polysaccharides. Other domains that can be incorporated include bioadhesive molecules, domains which convert from a binding domain to a nonbinding domain in vivo, and domains which convert from a nonbinding domain to a binding domain in vivo, as described in U.S. Pat. No. 5,410,016 to Hubbell et al. Examples of linking groups include biodegradable linkages, such as anhydride, ester, amide, and carbonate linkages. Examples of bioactive materials include proteins, sugars and polysaccharides, organic compounds with drug activity, and nucleic acids. The domains and/or linkages can selectively adhere to particular types of cells or molecules or be selectively degraded by enzymatic or nonenzymatic means. The domains may be a third type of polymer, for example, a biodegradable polymer such as a polyanhydride, polyhydroxy acid or polycarbonate. A peptide such as RGD, or even a single amino acid, which is used to target a polyamino acid for cleavage by an enzyme, can be incorporated into the polymer structure, to direct attachment, as discussed in more detail below.
Photopolymerizable substituents, including acrylates, diacrylates, oligoacrylates, dimethacrylates, or oligomethacrylates, and other biologically acceptable photopolymerizable groups, can also be added to the polymeric materials. These can be used to further polymerize the polymer once it is in contact with tissue or other surfaces, which can result in improved adherence to the surface.
C. Bioactive, Prophylactic, or Diagnostic Species
Bioactive, prophylactic, or diagnostic species can be attached to the copolymers, either covalently or ionically, or by mixing the species with the polymeric material, preferably before it is applied to the tissue.
A wide variety of biologically active materials can be encapsulated or incorporated, including proteins such as antibodies, receptor ligands and enzymes, peptides such as adhesion peptides, sugars, oligosaccharides, and polysaccharides, organic or inorganic drugs, nucleotides and nucleic acids, and cells, tissues or subcellular organelles or other subcellular components.
Bioactive species may be used to target adhesion of the polymeric material, to effect a biological activity at the polymeric material and tissue interface, or to effect an activity when the bioactive species is released during degradation of the polymeric material.
Exemplary ligands include the pentapeptide Tyr-Ile-Gly-Ser-Arg (YIGSR), which supports endothelial, smooth muscle cell, and fibroblast adhesion, but not platelet adhesion; and the tetrapeptide Arg-Glu-Asp-Val (REDV), which has been shown to support endothelial cell adhesion but not that of smooth muscle cells, fibroblasts, or platelets, as described in Hubbell et aL, Biotechnology 9:568-572 (1991). YIGSR, from laminin, binds to receptors on endothelial cells, but not on blood platelets. Thus, application of a copolymer having conjugated thereto the peptide YIGSR to a damaged vessel wall would be expected to block thrombosis on the vessel wall but not to block reendothelialization from the surrounding undamaged vessel wall.
Exemplary diagnostic agents include diagnostic enzymes and radiolabelled and fluorescent compounds.
A. AB Block Copolymers
An AB block copolymer, where A refers to the adsorbing segment and B refers to the non-adherent section, can be made starting from a peptide prepared using standard techniques, such as Fmoc peptide synthesis. For example, a cysteine residue can be inserted in the peptide for selective reaction with monomethoxy-PEG-vinylsulfone (monomethoxy-PEG-SO2CHCH2). Lysine residues can be inserted in the peptide for reductive amination with 4-formylphenylboronic acid. Alternatively, 4-carboxyphenylboronic acid can be synthesized as described by T. Kimura et al., Journal of the Chemical Society Perkin Transactions 2 10:1884-1894 (1995) and references therein. This can be converted to the acid chloride with SOCl2 or activated with a group such as carbonyldiimidazole or N-hydroxysuccinimide, then reacted with lysine residues. These two techniques allow lysines that are not derivatized to be intermixed with lysines that are bound to PBA groups. This can be achieved by using a low acid cleavable group, such as a 4-methyltrityl group, to protect lysines that will be reacted with PBA and using a conventional protecting group, such as t-utoxycarbonyl, to keep remaining lysines protected until the peptide-PBA compound is cleaved in 95% trifluoroacetic acid. Another alternative is to place aspartate or glutamate residues in the peptide, activate the carboxyl groups with carbonyldiimidazole or N-hydroxysuccinimide, and then react the activated carboxyl groups with 3-aminophenylboronic acid. Another option is to place serine or threonine in the peptide, react the hydroxyl groups with bisoxirane, and react the product with 3-aminophenylboronic acid. In all cases, reactions with the N- and C-terminus can be eliminated by placing N-acetyl glycine at the N-terminus of the peptide and using a peptide synthesis resin that yields an amide C-terminus. Also, a glycine spacer can be placed between the cysteine residue and the other residues, to make the cysteine more accessible to reaction with PEG. Other well defined polymer geometries such as ABA or oligo(AB) can also be synthesized using these methods.
B. A(dendrimer)B Block Copolymers
An A(dendrimer)B block copolymer of PEG and PBA can be synthesized from a monomethoxy-PEG-lysine(dendrimer) compound as described by D. L. Elbert et al., Chemistry and Biology 5:177-183 (1998). After the final generation of lysines has been coupled to the compound, the lysines can be derivatized with PBA using any of the methods described above, including a method whereby a desired amino acid is reacted with the xcex5-amino group of lysine and then reacted with the PBA moiety of the newly added amino acid.
C. A-g-B Comb Copolymers
An A-g-B comb copolymer can be synthesized starting from poly(lysine), or starting from a random copolymer containing PBA. Starting from poly(lysine), PBA groups can be added by any of the methods described in the AB block copolymer section (the ratio of PBA reactants to lysine amines present can be varied for the desired ratio of PBA to lysines).
Monomethoxy-PEG can then be added by activating the PEG with carbonyldiimidazole or N-hydroxysuccinimide, and reacting the product with remaining free lysines in the copolymer. Alternatively, a random copolymer can be synthesized that contains PBA and amine groups, such as those synthesized by D. Shino et al. (D. Shino et al., Journal of Biomaterials Science Polymer Edition 7:697-705 (1996) and references therein), but incorporate a group containing a primary amine, such as 4-vinylaniline. Monomethoxy-PEG can then be grafted as just described.
D. Optimization of the Polymeric Material for Specific Applications
The biological performance of the copolymers can be optimized by altering the structure of the copolymers, the ratio of the number of tissue binding polymers to nonbinding polymers, and the ratio of the mass of the tissue binding polymers to nonbinding polymers.
In some cases, polymeric materials that degrade by multiple mechanisms can be used. For example, degradation by nonenzymatic hydrolysis will depend primarily upon the accessibility of the polymeric material to water and the local pH. Given that pH and water concentration are similar throughout many parts of the body, this would result in a decrease in repellency as a function of time. As another example, if the degradable region is cleaved by an enzyme which is not highly regulated but is present in body fluids at a more or less constant level, the rate of loss of repellency depends primarily upon time. As another example, if the degradable region is cleaved by an enzyme which is more highly regulated, the rate of loss of repellency will be a function of enzyme activity. For example, during migration, many types of cells express the proteases plasmin or collagenase. Incorporation of a region cleaved by a protease into the polymer allows the polymer to be degraded by cells migrating onto a surface covered with the polymer, so that they can attach to and recolonize the surface. The biological performance of these polymeric materials depends upon their structure. Specific features affecting biological performance include degree of binding to the tissue, degree of repulsion of opposing tissues, duration of binding to the tissue, duration of repulsion of opposing tissues, and the mode of loss of binding or repulsion. Specific features of polymeric material structure include the chemical composition of tissue binding and nonbinding domain, the ratio of the mass of binding to nonbinding domains, the number of binding to nonbinding domains, the inclusion of sites that are particularly susceptible to nonenzymatic hydrolysis, the inclusion of sites that are particularly susceptible to enzymatic hydrolysis, and the inclusion of sites with particular biological affinity or activity.
The degree of protection of the treated surface depends on the length of time that the copolymer remains on the surface. For example, the rate of copolymer desorption from the surface depends on the number of adhesive (PBA) groups and on the size and number of non-adhesive (PEG) groups in the copolymer. Polymers with lower relative amounts of PBA would be expected to cause less activation of cells, since polymers with higher relative amounts of PBA will tend to crosslink more receptors, thereby creating a signal for cell activation.
Degradable links can be introduced within the copolymer by introducing ester moieties, such as lactic acid, added by ring opening polymerization of D,L-lactide, or enzyme cleavage sequences, in the backbone or in the backbone linkage to PEG to affect the in situ lifetime of the copolymer. D-amino acids can be used in place of any L-amino acids to reduce the rate of enzymatic hydrolysis in vivo and perhaps to reduce immune response. The boronic acid groups of PBA can be protected as described by Malan et al. or James et al. C. Malan et al., Synlett 2:167-168 (1996); T. D. James et al. Chemical Communications 6:705-706 (1996).
All of these parameters can be varied in the design of the copolymers described herein, and used in various combinations as necessary for the specific medical purpose for which the copolymer is needed.
A. Prevention of Adhesions and Abnormal Proliferation
The copolymers can be used to treat any site at which undesirable adhesions could form. These include primary, and especially secondary, adhesions in the abdominal cavity, including intestine to intestine, and intestine to peritoneum; in the pelvic cavity, including adhesion of the uterus, ovaries or fallopian tubes to other structures including each other and the pelvic wall; in tendons and their support structures, including tendon to pulley or to synovium; in the repair of nerve sheaths; in repair of the spinal column or disks; in the pericardium; in treatment of joints for inflammation and to prevent pannus formation; and in any other situation in which adhesions form which impair function or cause pain. The compositions can also be used to prevent undesirable tissue proliferation, as in restenosis, repair of keloid or hypertrophic scars, hypertrophy which obstructs ducts, such as benign prostatic hypertrophy, and endometriosis.
Alone or in combination with prevention of adhesions and cellular proliferation, the copolymers should be useful for delivery of bioactive compounds; prevention of thrombus formation at blood vessel surfaces, for example, following angioplasty; alteration of cellular attachment, especially to prevent cellular attachment, and therefore decrease metastasis of tumor cells; and coating of prosthetic implants such as heart valves and vascular grafts derived from processed tissues.
The polymeric materials can be locally or topically applied for local or systemic drug delivery. Typically, materials will be applied by spraying or injecting a very thin layer (usually on the order of monolayers of polymeric material) onto the surface to be coated. Methods for applying the polymeric materials in this manner are known to those skilled in the art.
The copolymers can be applied as a solution at the time of or shortly after tissue injury to protect the damaged surfaces during healing. This could be useful following virtually any surgery that is known to be followed by problematic wound healing responses, especially where cells, tissues, or scar tissue are typically laid down in the damaged areas, for example, cataract surgery, surgery in the peritoneal cavity, balloon angioplasty, cancer surgery, and organ transplantation. The copolymers are also useful for application to tissues which have been cauterized, stapled, dilated, treated by heating or cooling, treated by ionizing radiation, or treated by optical irradiation.
The copolymers can be applied using a catheter or using other minimally invasive techniques.
B. Coating of Non Biological Surfaces
The polymeric materials can also be applied to a nonbiological surface, such as one containing hydroxyl or carboxylic acid groups, intended to be placed in contact with a biological environment. Such surfaces include, for example, catheters, prosthetics, vascular grafts, contact lenses, intraocular lenses, other implants and ultrafiltration and dialysis membranes, and containers for biological materials. All of these surfaces include an entity such as, for example, a cellulose derivative that will interact with the adherent functionality. Additionally, cell culture dishes, or portions thereof, can be treated to minimize adhesion of cells to the dish. Cell culture dishes treated in this manner only allow spreading of anchorage dependent cells (cells which must be anchored to a solid support in order to spread) in those areas which are not treated.
Deposition of biological matter on metal surfaces can be minimized by coating the surfaces with the polymeric materials. The compositions could effectively bond to surfaces containing metal oxides such as iron oxide, titanium oxide and silicon oxide. The metals are treated with the copolymer as a part of conduit or device manufacture, or are treated in situ, following assembly of the conduit or device, or as part of the normal operation of the device. The copolymers may be applied by adsorption of the polymeric materials from a liquid solution, or by spraying. Removal of the polymer from the metal via a change in pH, or other means, may also be used as a cleaning step as a part of the normal operation of a device using this technology. The copolymer layer can then be reapplied to the metal, resulting in a resumption of the protein-repelling properties at the treated metal surface.

Methods and compositions to prevent formation of adhesions in biological tissues


This invention, though preferably applied to aircraft structure, has application to foil-bearing devices in general, creating structure somewhat similar to the structure of a mobius band surface which characteristically rejoins to itself, because said structure produces unique continuity of one surface blending into a subsequent one, said structure most often having opposed higher and lower pressure-dynamic surfaces. These xe2x80x9cmobius-likexe2x80x9d structures join foil segments and complementary surfaces to specific fluid-dynamic components (foil segments joined to foil extensions, shaped and contoured panels, subsequent foil segments, and moveable surfaces) such that there is particular unique continuity of a first fluid-dynamic component to a subsequent one thus more effectively utilizing foil-created fluid-dynamic pressure flow for orchestrated lift and thrust production and reducing vortex-induced fluid-dynamic drag than have other inventions of the prior art.

1. Field of the Invention
This invention relates in general to certain new and useful improvements in fluid-dynamic efficiency of wings and fluid-dynamic foils which are employed in dual or multiple foil structures or in joined segments of foils that are split into segments and rejoined.
2. Description of the Prior Art
Airfoil shapes and foils moving through a fluid produce pressure differential as roughly defined by the term xe2x80x9cliftxe2x80x9d. By producing pressure differential, a pattern of circulation is produced around the advancing foil. This circulation is continuous around the length of the foil and is known as a xe2x80x9cvortexxe2x80x9d, or xe2x80x9cvortical flowxe2x80x9d. This vortex remains xe2x80x9cboundxe2x80x9d around a conventional airfoil the length of the surface from root to the tip. The same phenomenon occurs with all fluid foils creating pressure differentials similar to lift. Beyond the tip of conventional fluid foils this rotating fluid circulation xe2x80x9cshedsxe2x80x9d off into tornado-like xe2x80x9cfreexe2x80x9d vortices or, in the case of aircraft a trailing xe2x80x9cwingtip vortex.xe2x80x9d Each shed vortex tends to grow into a tighter and more compact rotating fluid mass as it leaves each tip surface into the xe2x80x9cfree streamxe2x80x9d because the differential in pressures (lower pressure from the upper side of the foil and higher pressure from the opposite side of the foil) are attempting to equalize. The vortex, with its high-pressure outer layers rotating rapidly, draws the high-pressure component into its lower pressure core. This suction-creating effect produces undesirable lift-induced drag. The pair of shed tip vortices typically trailing behind conventional aircraft exemplifies this. When in flight, small vortices also shed from the trailing edge of conventional aircraft wings, but the primary drag-inducing vortices are those shed at the outer wingtips. These vortices contain tremendous quantities of rotating mass fluid-dynamic energy.
Long tornado-like rotating vortices behind large aircraft may continue for hundreds of feet or even miles, depending upon the weight of the aircraft, wing area, aspect ratio, and other variable factors. In some cases these vortices endanger other aircraft that may be entering the wake of these energy-laden vortices trailing the aircraft. It becomes obvious that trailing vortices in addition to creating tremendous amounts of fluid-dynamic drag also can be hazardous to pilots and passengers flying small aircraft where larger aircraft are departing and arriving.
Reducing induced drag results directly in decreasing the amount of energy required to sustain fluid-dynamic foil induced lift The purpose of all attempts to reduce drag is energy conservation of one form or another. Some inventors have sought to reduce induced vortice-created drag in aircraft by use of such devices as end plates, winglets at wing tips, propellers with winglet-like projections at the blade tips. Some inventors have sought to improve aerodynamic efficiency by using joined wing systems on conventional fuselages. Joined wings have inherent rigidity and some fluid-dynamic advantage over conventional wings, but there are inherent inefficiencies in prior art joined wing systems in that they do not employ devices that would eliminate or greatly reduce the drag penalty from vortex-induced drag. Up to xc2xd or more of all induced drag of conventional wings is due to xe2x80x9cvortex sheddingxe2x80x9dxe2x80x94the resulting creation of free vortices from fluid-dynamic foils in the process of producing lift.
Most the multi-wing creations of previous inventors have not reached the maximum potential of aerodynamic efficiency and drag reduction. In spite of the positive (theoretically and experientially demonstrated) potential of joined wing aircraft to reduce induced drag, most joined wing aircraft have wing intersections that unfavorably translate wing tip pressures from the leading wing to the following wing. Forward placed airfoils are commonly joined to aft ones such that vortice translation creates oppositional interference when translated pressure mass from the first airfoil interfaces with counter-rotating circulation mass of the subsequent foil. One advantage of structurally joining wingtips is a shorter, yet stronger span for the same amount of wing area. Decreased wing length results in decreased bending moments. When a wingtip union is properly designed to translate the circulating fluid mass without letting it shed as a vortex, it can also be designed to utilize this potential energy for forward thrust and lift augmentation to the rear lifting surfaces (in a joined wing, biplane system or multilayered wing arrangement). The ideal wing system would reduce overall induced drag rather than creating unwanted induced vortex drag. Utilizing such an invention would enable a designer to significantly reduce wing area because the wing system is producing more lift per square area unit. Reducing wing area also means less profile drag and the amount of energy necessary to sustain forward flight is greatly decreased. The ultimate improvement of aerodynamic or fluid dynamic foils would be to eliminate practically all foil-tip vortex-induced drag by translating this fluid-dynamic flow from a leading foil pair to corresponding surfaces of subsequent foils behind said leading foil pair, or to convert this vortical energy into forward thrust, or both. The ultimate increase in efficiency would result from utilizing inventions which eliminate the greater percentage of all wingtip vortex-induced drag, thus the effect of xe2x80x9cinfinitexe2x80x9d wing is more nearly realized without the more extensive structure and subsequent weight penalty resulting from strengthening and lengthening wings to a high aspect ratio.
Vortex shedding at the wingtips is a performance liability for conventional aircraft: Shedding wingtip vortices produce xc2xd or more of the total induced drag of lifting airfoils (wings and propeller blades). Shedding vortices are what causes increased noise from rotating blades and propellers. Inventions such as the xe2x80x9cQ-Tipxe2x80x9d propeller modify shedding vortices to minimize noise produced at the tips. Other inventions have been created for use on conventional aircraft wingtips and propellers to reduce drag and utilize the dynamic energy contained in these vortices. Such inventions reduce the drag-producing component by xe2x80x9cdiffusingxe2x80x9d or xe2x80x9cdissipatingxe2x80x9d or xe2x80x9csuppressingxe2x80x9d these vortices. xe2x80x9cWhitecomb Wingletsxe2x80x9d or Hachett""s Vortex Diffuser (U.S. Pat. No. 4,190,219) were each designed to disperse the vortex somewhat and also convert vortical energy into forward thrust. Small winglets such as these can improve wing efficiency somewhere near 15%. Most devices that are designed for conventional wings to disperse, reduce, or utilize tip vortice dynamic pressures function with varying, but limited degrees of efficiency in drag reduction. Previous attempts to significantly reduce drag due to vortex shedding have produced limited degrees of success.
Methods of modifying the wingtip vortex formed at the outer tips of airfoils have included the use of end plates to reduce vortex shedding and multiple vanes to xe2x80x9csplitxe2x80x9d, xe2x80x9cdiffusexe2x80x9d or weaken the vortex, thus lessening vortex-induced drag. Attached panels and upward or downward turned tips have been used with varying degrees of success to present. Some inventions break larger vortices down into multiple smaller vortices to lessen vortex-induced drag, thus not allowing a single trailing vortex to form off each wingtip. Such devices are attempts to reduce kinetic energy in the wake of the wing, and consequently lessen induced drag. Richard Vogt (1951, U.S. Pat. No. 2,576,981), Alexander Lippish (1956 U.S. Pat. No. 2,743,888), Clarence C. Cone, Jr. (1966 U.S. Pat. No. 3,270,988), and Scott Rethorst (1973 U.S. Pat. No. 3,712,564) each invented wingtip devices to diminish vortex-induced drag in aircraft. Nonetheless, such attempts have produced only limited improvement in induced drag reduction.
Dr. Richard T. Whitcomb of NASA (inventor/developer of the xe2x80x9cVWhitcomb Wingletxe2x80x9d) in his presentation of CONCEPTS FOR DRAG REDUCTION OF AGARD/VKI outlined the problem and suggested solutions and objectives in the section entitled xe2x80x9cMethods for Reducing Subsonic Drag Due to Lift.xe2x80x9d To utilize more effective methods of vortex-induced drag reduction and improve wing efficiency has been the objective of certain inventors who perceive that joined wing systems could be more efficient, could have better structural strength-to-weight ratio, and could provide better crash protection for passengers and pilot. Such aircraft employ dual airfoils (i.e. forward and aft pairs of wings) joined structurally such that united members ideally create little or no aerodynamic interference or even contribute to aerodynamic function by use of control surfaces, with unions that add rigidity and strength to the wing structure. Without additional special structure that changes fluid dynamic flow characteristics, joined wing systems produce only marginal drag reduction results.
Geraci (U.S. Pat. No. 2,576,294) showed a box plane configuration. Outer wingtip unions are curved such that the vortical flow of the primary wing continues outward and up to the second. The primary wing""s lift-induced vortical flow is directionally opposite to the normal pattern of vortical flow around the second wing. Both wings are swept the same direction and joined such that lower surface of the first wing transitions to upper surface of the second wing and the bottom of the first continues into the top of the second. Because interfacing lift-induced bound vortices of each adjacent wing pair rotate directionally opposite, unfavorable interference is produced. Geraci""s invention included a joined blade propeller which functions in a manner similar to joined wing systems, but this joined blade propeller suffered the same limitations inherent in conventional unmodified joined wing systems.
Zimmer (U.S. Pat. No. 4,090,681) utilizes two sets of wings forming a closed frame. All wings are rearward swept. The aft set of wings attaches to the fuselage at a lower level than front wings. The vertical fin does not support the wing. Wings are joined at the outer tips of each adjacent pair either by a flat plate or small rounded tip. There is no provision for optimizing the fluid-dynamic flow such that formed vortices are minimized or eliminated.
Ratony (U.S. Pat. No. 3,981,460) discloses an aircraft with swept back and swept forward wings that form a closed triangle or xe2x80x9cdiamondxe2x80x9d shaped frame in front elevation view. The wing is essentially a continuous loop and is supported at the roots only. In a second patent, Ratony (U.S. Pat. No. 4,053,125) shows fore and aft wing pairs joined at the tips either with a tank-like tip or a curved continuation of the first wing""s upper surface into the correspondingly opposite (i.e. the bottom) of the second. The surfaces are not linked corresponding surface to corresponding surface. Wings overlap somewhat producing greater than normal potential for fluid-dynamic interference and vortex shedding.
Miranda (U.S. Pat. No. 3,834,654) discloses an aircraft that uses forward swept rear wings and rearward swept forward wings that are connected by vertical panels forming a rectangular box configuration. Structural stiffness against side forces is limited in that it has no diagonal members. The vortical flow components of either forward foil of the pair would tend to create interference with the vortical flow component of each corresponding aft-located foil. Each said aft located foil is attached inboard at a location higher on the fuselage than said forward foil is attached. The vortical circulation produced by said forward foil would move upward and outboard, rotating around said forward foil from the root of said foil to the outer foil tips and around the vertical panel until it interfered with the lift-induced oppositely rotating vortical flow of said aft located foil. The counterrotating vortices produced interfere with each other. The result is disadvantageous lift-neutralizing effects on aircraft configured with this version of a joined wing system.
Wenzel (U.S. Pat. No. 4,146,199) demonstrates an aircraft comprised of an unconventional lifting fuselage having flat panel sides to which two wing pairs are attached. The rear wings are swept forward at negative dihedral, and the forward wings are swept rearward, each wing joining its adjacent neighbor wing at the tip. These wings are joined by a curved surface, somewhat horseshoe shaped in front or rear elevation view. As with the Miranda and Geraci designs, the outward travelling bound vortex of the front wing continues circulating around the wingtip union outward to finally interfere with the normal rotational direction of the lift-induced bound vortex circulating around the second wing.
Joined wing systems using any of the above-described techniques of fuselage attachment can be adapted to many existing aircraft with simple modifications and strengthening of structural members. The practical technology for development of joined wing aircraft is currently established in practice by NASA and by inventors who have contributed significantly to this technology, but the problem of successfully eliminating major amounts of vortex-induced drag has not been well resolved in previous inventions. What had been needed is a complement to the prior art that would resolve long-standing problems of vortex-induced drag and fluid-dynamic inefficiency inherent in fluid-dynamic systems. The problem of fluid-dynamic inefficiency and thus prevention of energy loss from fluid-dynamic drag has been only partially addressed by practitioners of the prior art.
This invention consists of joining adjacent fluid-dynamic foil segments by using mobius-like structures or segments of somewhat mobius-like elements to unite said adjacent fluid-dynamic foil segments so that there is a continuity of first fluid-dynamic foil surface into the corresponding subsequent fluid-dynamic foil surface.
When joining a first foil segment to a subsequent foil segment the top surface of said first foil segment is continuously joined to top surface of said subsequent foil segment and the bottom surface of said first foil segment is continuously joined to the bottom surface of said subsequent foil segment. These continuously joined surfaces translate vortical fluid-dynamic pressure flow from the first surface to subsequent surfaces such that major xe2x80x9cfreexe2x80x9d vortices are inhibited from forming at the outer tips of said first foil. The pressure-dynamic flow of the xe2x80x9cboundxe2x80x9d vortex circulating around said first foil can be thus translated by means of the moblus-like structure or segment of mobius-like structure to said subsequent foil surface. Said translated fluid-dynamic pressure flow tends to favorably intercept and instead of contradict, actually complement or augment the lift-induced circulating pressure-dynamic vortex bound around said subsequent foil surface. Some of this bound vortical energy may be converted to forward thrust by calculated arrangement of specific elements of this invention. The union between said first foil""s outer tip and said subsequent foil""s outer tip can be curved, twisted, bent, or canted for maximized induced drag reduction as needed for specific application and to meet the aesthetic requirements of the particular design being created or a unit can be retrofitted to an existing foil/body arrangement by developing the particular shape of mobius-like structure necessary for both complementing the particular design and achieving the specific fluid-dynamic effect and specific efficiency desired.
By maintaining continuity of cambered forward wing surface joined to corresponding rear wing cambered surface, this invention inhibits xe2x80x9cvortex interferencexe2x80x9d and xe2x80x9csheddingxe2x80x9d. As rudders, wings and elevators vary in shape, size, dihedral and thickness for structural, performance, or sometimes for aesthetic reasons, likewise variations in the appearance of this invention will manifest for the same reasons. Though different in appearance, each variation is fundamentally the same method of uniting foil surface to foil surface with one principle mode of function exclusive to the invention. While the principles of the invention is made clear in illustrative embodiment, it will become immediately obvious to those skilled in the art that many modifications of structure, arrangement, proportions, elements, materials, and components used in the practice of this invention can be particularly adopted for specific environments and operating requirements without departing from the principles of its operation and arrangement. It will be obvious to those skilled in the art that many modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.
The effect of using this method of utilizing moblus-like unions or segments of mobius-like structure for joining adjacent wings or fluid-dynamic foils is to produce one continuous vortical circulation pattern that does not shed into the free stream but instead stays in circulation from the first foil toward the tip, transitioning across the tip union and around the subsequent foil without the typical occurrence of vortices shedding into the freestream. When applied to aircraft structures using the joined wing system for example, the fuselage or rudder acts upon said circulation pattern as would a final end plate on a wingtip and does not allow this return fluid-dynamic flow to shed as a tip vortice. In effect this structure acts more closely like aerodynamic theory""s description of an ideal no-induced-drag xe2x80x9cinfinite wingxe2x80x9d than does a conventional or joined wing in spite of limited span of low aspect ratio.
Classical aerodynamic theory postulates that an infinitely long wing would produce absolutely no induced drag. Comparing the lift to drag (L/D) ratios of long-winged xe2x80x9chigh aspect ratioxe2x80x9d gliders with shorter winged craft having the same wing area but using smaller aspect ratio wings upholds the validity of this theory: Long, high aspect ratio foils produce less induced drag than shorter low aspect ratio ones. There is proportionally less vortex shedding on a high aspect ratio foil than on a low aspect ratio foil. One can infer that reducing or eliminating the production of free vortices created by lifting foils would greatly enhance fluid-dynamic efficiency of a set of fluid-dynamic foils. The effect of this invention in diminishing vortex shedding would be similar to the effect of increasing the aspect ratio of a wing without the normal problem of incurring major weight penalty by adding sufficient structure necessary to strengthen and stiffening an extended, more efficient wing.
Application of said invention would demonstrate function that is more fluid-dynamically efficient and more useable than existing systems. Said invention can be integrated into existing foil systems and designed compatible to particular shapes with function in mind, but also proportioned in harmony with an eye toward aesthetic appeal which is a realistic necessity for marketing a product or modification of an existing design. Said unions should appear xe2x80x9cintegratedxe2x80x9d with a specific aircraft design without changing the fundamental pressure translating function of said invention. Unions described herein should be adaptable to change of shape, proportion, arrangement, and combination in tandem or multiples. They should maintain integrity of function according to specific principles of operation described herein even if said union""s proportions are changed to aesthetically and functionally suit a particular aircraft configuration to which it is applied. Said invention""s universal application demands that it must be adaptable to rearrangement of elements and change of materials and components without departing from a principle mode of operationxe2x80x94whether employed singly or as multiples in tandem, and can therefore appear quite different in different applications, yet it will be the same invention operating according to said principle mode of operation, i.e. the favorable translation of fluid-dynamic flow from one foil segment to a subsequent foil segment by means of using said mobius-like structures or said segments of mobius-like structure to unite adjacent foils.
Said invention described herein uniquely complements the prior art and related inventions. Said invention can be directly adapted to most joined wing systems, similarly arranged propellers, and fluid-dynamic devices configured to utilize said principle mode of operation. The result is greatly improved fluid-dynamic foil efficiency and reduction of induced drag.
Properly utilizing vortical energy potential available at the outer tip of a lifting foil system produces these results: minimal induced drag, positive vortical translation, extraction of forward thrust from differential pressure flow, and efficient translation of directionally-correct vortical circulation around the wing. The advantages for aircraft are: the effect of high aspect ratio wings using shorter wing-spans, less structural weight, greater wing stiffness, and greater compactness. By utilizing panels that unite one or more foil segments to another (i.e. when using more than two foils, uniting the subsequent foil and the next subsequent, etc.), a more efficient path for vortical flow transition is formed. This can be accomplished by arranging panels such that they give the appearance of being doubled over or bent. These panels unite two or more foil segments so that corresponding opposite surfaces of both foils are continuously united such that upper surface of the first foil segment transitions into upper surface of the subsequent foil segment, and opposite surface of said first foil transitions into opposite surface of said subsequent foil segment. These panels which unite foils can be molded, constructed, or shaped to be efficient, strong and aesthetically balanced. Specific portions of these panels with a shape that appears doubled over result in a load-bearing union that favorably translates vortical flow from a primary foil to one or more successive ones. This invention is meant to be used as a universal upgrade for specific wing systems, greatly improving the efficiency of its operation, resulting in energy conservation.
It is intended that this invention be integrated with existing configurations either during manufacture or as accessory retrofit. By varying proportion and combination of elements without departing from the basic function and spirit of the invention, it can be integrated into different aircraft designs to maximize efficiency and maintain style continuity.
This invention""s potential application goes beyond xe2x80x9cjoined wingxe2x80x9d aircraft. When properly configured for each specific application, singly, in tandem, or in multiples, it can greatly improve efficient operation of varying aircraft such as biplanes with joined wingtips, joined tip canard systems and aircraft having rear tail planes joined to wingtips.
This invention relates to aircraft specifically and in general to all similar fluid-dynamic devices that create lift or thrust by use of one or multiple foils. Application of the moblus-like union of foils is not limited to aerodynamics, but as well to other fluid-dynamic devices such as hydrofoils and fluid-dynamic blades or rotary blade systems that extract energy from or add energy to the fluid medium they traversexe2x80x94which is the essence of fluid-dynamic interraction between foils and fluid mediums.
One potential for application is in use with rotary wings such as those found in helicopters. A set of rotating foils typically used on a helicopter has blades which are essentially lift and thrust producing foils which rather than remain fixed on a fuselage, instead rotate about an axis, but still function as foils producing lift. In practice such foil sets can be correctly defined by observing their principle mode of operation. Rather than being something other than foils that are simply wings or foils that are just propellers or foils that are only rotary wings, in essence all wings, rotary wings, or propellers are the same entity. They are simply lifting foils operating in various attitudes and with different applications, using the same principle mode of operation. Some craft have rotary wings that once in flight are transitioned from horizontal to vertical orientation, suddenly becoming propellers rather than as formerly, rotary wings, until there is reversion to previous attitude for landing. These foil sets have not changed in function, structure, or mode of operation other than orientation in space producing forward thrust rather than lift. Forward thrust created by blades is in essence simply horizontally applied lift. The terms thrust and lift by popular definition are considered dissimilar, but as applied to fluid-dynamic foils in practice and observation, they are identical except that propellers are applied in roughly a horizontal plane, creating horizontal lift while spiraling through the fluid medium in which they operate. Wings likewise operate in roughly a horizontal plane, do not spiral but utilizing fluid-dynamic flow over foil surfaces create upward lift while travelling in a linear direction. The rotary wing likewise produces lift in roughly the upward direction, as does the wing, but spirals through the medium as does the horizontally travelling propeller. Gravitational force is the only other major factor that affects them both in similar and dissimilar ways simultaneously. In the first case, rotary wings and conventional lifting foils generally create lift in 180 degree opposition to gravity, and in the second case, propellers and fans create lift largely in the horizontal plane at approximately a 90 degree opposition to the force of gravity. In essence, a lifting foil is the same device whether it is travelling upwardly, horizontally, or spiraling through the medium it traverses.
Foil-produced lift and foil-produced thrust are in essence the same thing. The principle of operation is the same in spite of differences of terminology we have applied to the phenomenon because of the influence our prevailing cultural orientation has had upon our language. Our language useage influenced by our culture can mislead our perception of technology. When a foil surface is passed through a fluid, pressure differential influences the foil to move toward the direction of the least pressure or foil shape causes pressure differential on opposite sides of the foil. The same principle governing foils interacting with fluids applies whether the result is horizontal movement produced because force moves the foil along a spiral path; it is the same principle governing when horizontal linear force applied to a foil produces lift which is perpendicular to the plane in which the force is applied; it is the same principle governing when vertical movement is produced because force moves the foil along a spiral path. Foil-produced lift and foil-produced thrust are the same phenomenon, the extraction of energy from fluid-dynamic flow, in spite of our language.
Rationally, application of this invention would be to fluid-dynamic foils in general, because they are by means of the pressure differential creating lift or thrust, which in essence is the same thing.
Mobius-like unions or segments of mobius-like structures can be used to join fluid-dynamic foils that are xe2x80x9csplitxe2x80x9d into separated segments and united again in order to increase fluid-dynamic efficiency of the united foil system. These foil segments, though rejoined to the original foil segment, are equivalent to separate foils joined to one another, in that they are separate foil segment which are joined with the initial foil. In appearance they look to be miniature joined wing-like structures on the tips of a conventional wing, and they are in essence the same thing, just terminating differently, because they function according to the same operating principle of this inventionxe2x80x94that of redirecting fluid-dynamic pressure flow by maintaining continuity of corresponding surface to corresponding surface when joining pressure-dynamic surface to subsequent pressure-dynamic surface.
It is also possible to utilize this invention to redirect fluid-dynamic pressure through channels or pathways formed by moblus-like unions joined to foils and foil segments. This redirected fluid-dynamic pressure flow can be utilized to cool propulsion systems, engines, and other devices. This redirected pressure flow can also be used to supply and augment pressure used or created by propelling devices and engines. Additionally foil systems utilizing mobius-like structure to unite them can both supply surface burning propulsion devices with pressure-dynamic flow, and in some cases even be the specially prepared surfaces upon which the fuel ignites and burns.
In some cases it is desirable to add xe2x80x9clips,xe2x80x9d or xe2x80x9ccuffsxe2x80x9d and extensions to existing mobius-like structure in order to improve fluid-dynamic function and to enhance creation of thrust from redirected fluid-dynamic pressure flow. It is also possible to extend said lips or cuffs into longer, more tubular shapes while still maintaining the principle mode of operation of this invention, namely translation of pressure-dynamic flow from one foil segment to another fluid-dynamic advantage.
Mobius-like structure can be used to join said foil segments or said foils to helical-shaped foil segments which are xe2x80x9cwrappedxe2x80x9d directionally opposite to the rotational direction normal to that of a shedding vortex. This causes pressure-dynamic flow to be turned inward and opposite the direction normal to rotation of a shed vortex. Greater thrust potential is achieved and vortices are inhibited from forming as they would with use of conventional foil surfaces not having modification. This helical curved foil segment joined to a previous foil segment would also lend itself to surface burn technology. The high pressure from the lower foil surface would supply the burn surface with fluid-dynamic pressure flow, and the surface formed would be designed to function as a burn surface. Thus combustion would occur directly upon specific parts of the configuration formed by said mobius-like structure joining foils and subsequent foil segments, and consequently thrust would be produced. The mobius-like structure joining foils described herein would easily lend itself to adaptation of this kind of technology. Such technology combined with this invention has application to wings, helicopter blades, propellers, and other devices which are likewise foil-based fluid-dynamic systems operating in a fluid medium.
This apparatus has a wide range of potential usage and attachability to an almost unlimited array of structures, particularly those that function in fluid media, and can be joined to various intermediate attachment structures: transportation and vehicular structure in some cases; some automotive systems utilizing foil structure; aircraft structure (which includes ring wings, biplanes, monoplanes, canard aircraft, C wing structure, joined wing, channel wing, boxplane, lifting fuselages and others); various foil structures and attachment methods (joined foils, intermediate foils attached to other surfaces, foil tip and root structure, apparatus tied directly to spar structure, winglets, joined tips, airfoil tip structure, ducted fans, rotary wings, foil structure split into segments, propellers, swept wings, straight wings, delta wings, and cambered surfaces generally including rudders and elevators). Use of these unions results in:
A. Mobius-like fluid-dynamic structure which will modify the vortex shedding characteristics of foil tips.
B. Structurally rigid unions of foil segments and complementary fluid-dynamic shapes that modify fluid-dynamic pressure flow.
C. Mobius-like structure that modifies segmented foil tips so that they become more efficient fluid-dynamic shapes.
D. Creation of fluid-dynamic unions by uniquely reuniting segments of an individual segmented foil.
E. Fluid-dynamic structural unions comprising segments of separate foils that are rejoined for fluid-dynamic advantage.
F. Creation of structure and specific fluid-dynamic shape using mobius-like unions which direct pressure from one foil segment to subsequent foil segment such that favorable fluid-dynamic interaction between these foil segments is made possible for purposes of drag reduction (if adapted and designed correctly this invention has potential to be united with and improve the function of many of these structures: structure intended to extract thrust by means of fluid-dynamic function, structure intended to produce lift, structure intended to affect fluid-dynamic pressure differentials, structure intended to inhibit pressure differential from equalizing, structure intended to impel fluids, structure intended to transition fluid-dynamic flow, structure intended to cause augmentation of fluid-dynamic flow and structure intended to direct fluid-dynamic flow).
G. Mobius-like joining structure used to develop systems which can utilize combinations of foil segments, unions, complementing panels, and surfaces used for directing fluid-dynamic flow, for reduction of drag, for vortex reduction, for creating surfaces, for special-purpose flow functions, and incorporating drag reducing shapes to augment fluid-dynamic function (these forms of structure can be intended to produce directed thrust, to increase directional thrust, extract thrust by means of fluid-dynamic function, to inhibit pressure differential from equalizing, or to impel fluids. Any foil-related structure having material arrangement, fluid-dynamic element, and designed or proportioned components has potential for combination with this invention including crash protection structure having fluid dynamic characteristics, foils with end plate attachment or structure attached, such as loops, continuous structure, and structure having various aspect ratios).
H. Incorporation of added moveable control surface elements for directing flow and for modifying fluid-dynamic function used as a means to direct fluid-dynamic flow for lift augmentation, maneuver and flight control (structure for directing fluid-dynamic flow, structure for controlling fluid-dynamic flow, control apparatus structure, structure used for affecting fluid-dynamic flow; structure for affecting directional control, structure for affecting lift augmentation, structure for lift control, structure for affecting conventional maneuver, structure for affecting non-conventional maneuver).
L. Creation of mobius-like unions which, when combined with fluid-dynamic components, channel fluid-dynamic pressure to specific areas for utilization by fans, blades, engines, or other devices to propel fluids, for cooling, for use as augmenting fluid-dynamic pressure flow for propulsion purposes, or to be used as directed pressure flow to external burn surface propulsion systems (propelling structure, fluid-dynamic lift-producing structure, fluid-dynamic structure involved in thrust production, structure connected to propulsion devices or systems, rotating structure having fluid-dynamic elements, structure which extracts pressure-dynamic energy from fluid-dynamic flow, structure which utilizes foil structure to extract lift from fluid-dynamic flow, structure which translates fluid-dynamic pressure flow to another structure, structure translating fluid-dynamic flow to a subsequent sector of itself, fluid-dynamic structure passively activated by fluid-dynamic flow, foil structure actively modifying or affecting fluid-dynamic flow, helicopter structure, propeller blade structure, structure used for ducting fans, fan blade structure, pump structure, wind-operated foil-bearing fluid-dynamic structure, structure which embodies a plurality of said apparatus).
J. Using mobius-like structure to join foil segments to subsequent helical or spiral, or otherwise variously shaped foil segments as means of inhibiting vortex production by forcing fluid-dynamic pressure flow to rotate in a direction opposite the direction normal to a shedding vortex and to inhibit vortex shedding (these foil-related structures are intended to produce specific fluid-dynamic functions creating structure intended to modify vortex formation including vortex generator structure, structure intended to modify vortex intensity, structure intended to reduce vortex production resulting from fluid-dynamic function, and structure intended to reduce vortex drag).
K. Foil segments can be joined by mobius-like structural elements that have xe2x80x9clipsxe2x80x9d or xe2x80x9ccuffsxe2x80x9d extended from existing fluid-dynamic elements used as a means to augment efficiency and performance efficiency of foils and foil segments joined by said moblus-like structure or unions.
L. Having mobius-like structural elements join foil segments to subsequent helical (spiral) or variously shaped foil segments forming a fluid-dynamic surface components of a propulsion means used to produce surface burning propulsion (there are many composite systems having function to which variations of this apparatus can be attached for improving their operation: structure for cooling, structure used to augment pressure used by propelling devices and engines, structure of on-surface-bum devices which produce thrust directly on a fluid-dynamic surface, structure using on-surface-burn technology, structure used as a means of containing surface burn combustion).
M. Composite systems comprised of mobius-like structure joining foil segments that direct fluid-dynamic flow for developing thrust, or for use in other purposes that would utilize directed fluid-dynamic pressure from these unions (there are other structures for various fluid-dynamic purposes having diverse characteristics to which this apparatus may be attached for fluid-dynamic function purposes: structure having panel area which operates in a fluid medium, structure having curved shape which operates in a fluid medium, structure having shapes which modify fluid-dynamic pressure flow, the apparatus mounted to structure in tandem, the apparatus mounted to structure in multiples, foil structures that operate in fluid medium, foil-based systems that operate in a fluid medium, scale model structure, marine structure, boat structure, hydrofoil structure, underwater vehicle structure, structure which when combined with said apparatus forms loop or channel shape, foil structure having helical shape, multiple connections in array comprised of foil structure and said apparatus, structure comprised of foil segments and surfaces, structure comprised of foil segments and attached panels, structure comprised of foil segments and unions, structures used to reduce fluid-dynamic drag, structures used for creating new fluid-dynamic surfaces added to existing structure, structures incorporating drag reducing shapes, structure used as projectile or arsenal means, structure temporarily or permanently attached to projectile or arsenal means. There are other categories of foil-based devices having structure, having some fluid-dynamic characteristics, operating in fluid medium, and having the potential for application of this apparatus. These include: foil segment-bearing structure having recreational use; foil segment-bearing structure having commercial use; foil segment-bearing structure having transportation use; foil segment-bearing structure having military use; foil segment-bearing structure having decorative use; foil segment-bearing structure having presentation purposes; kite structure; toy structure; floating cube electric powered kite structure; floating cube aircraft structure; parachute structure; paraglider structure).
N. Fluid-dynamic structural elements which are joined to form surface continuity from a first element surface to surfaces on subsequent elements, creating shape which separates high pressure areas from low pressure areas, thus keeping high pressure flow transitioning across said subsequent surfaces, recirculating it over high pressure areas comprised of said first surface joined to subsequent surfaces which in turn are rejoined to first surface. By keeping high pressure flow on high pressure surfaces longer said fluid-dynamic elements which are joined are used as a means to favor thrust and lift being produced rather than production of shedding vortex. Foil-created high pressure is thereby inhibited from equalizing with low pressure flow and shedding as a vortex, but instead is caused to recirculate with this fluid-dynamic energy being converted to directional thrust and additional lift by the arrangement of said fluid-dynamic elements.

Mobius-like joining structure for fluid dynamic foils