Novel methods and compositions for treating aged and environmentally damaged skin are disclosed which provide improvements in the skin""s visual appearance, function and clinical/biophysical properties by activating at least one proteolytic enzyme in the skin""s stratum corneum. The disclosed treatment methods involve topical application of a novel cosmetic composition containing a combination of a cationic surfactant such as N,N,-dimethyldodecyl amine oxide (DMDAO), an anionic surfactant such as sodium dodecyl sulfate (SDS), or monoalkyl phosphate (MAP) and a chelating agent such as ethylene diamine tetraacetate (EDTA) to stimulate a chronic increase in the replacement rate of the skin""s stratum corneum by means of corneum protease activation. This chronic, low level stimulation is effective to induce repair and replacement of the stratum corneum, epidermis, and dermis of the skin and improvements in the appearance, function, and anti-aging properties of the skin.

The present invention relates generally to a treatment method and composition for improving the skin""s visual appearance, function, and clinical/biophysical properties which have been changed by factors such as chronological age, chronic sun exposure, adverse environmental pollutants, household chemicals, disease pathologies, smoking, and malnutrition. In particular, the present invention relates to a method of treating skin by increasing the skin""s stratum corneum turnover rate through corneum protease activation. More particularly, the invention relates to the use of a combination of a cationic surfactant such as N,N,-dimethyldodecyl amine oxide (DMDAO), an anionic surfactant such as sodium dodecyl sulfate (SDS), and a chelating agent such as ethylene diamine tetraacetate (EDTA) as additives to topically-applied cosmetic skincare products to treat and reduce the clinical and functional signs of aging and environmental damage in skin. The invention provides for an effective alternative to the use of hydroxy acids and retinoid compounds to treat aged and environmentally-damaged skin.
With chronological age and chronic exposure to adverse environmental factors, the visual appearance, physical properties, and physiological functions of skin change in ways that are considered cosmetically undesirable. The most notable and obvious changes include the development of fine lines and wrinkles, loss of elasticity, increased sagging, loss of firmness, loss of color evenness (tone), coarse surface texture, and mottled pigmentation. Less obvious, but measurable changes which occur as skin ages or endures chronic environmental insult include a general reduction in cellular and tissue vitality, reduction in cell replication rates, reduced cutaneous blood flow, reduced moisture content, accumulated errors in structure and function, and a reduction in the skin""s ability to remodel and repair itself. Many of the above alterations in appearance and function are caused by changes in the outer epidermal layer of the skin, while others are caused by changes in the lower dermis. Regardless of the stimulus for skin damage, when damage occurs, numerous natural and complex biochemical mechanisms are set into motion in attempts to repair the damage.
When the epidermis is injured, the epidermal basal cells respond to the injury by dividing at a more frequent rate. This increase in replication rate results in a more rapid replacement of the damaged epidermis with a new epidermis and stratum corneum, a process referred to as xe2x80x9cepidermal cell renewal.xe2x80x9d Common examples of injuries which can increase epidermal cell renewal rates include abrasion, chemical damage, pH extremes, excessive sun exposure, or allergic or non-allergic contact irritation. If the injury is too severe, the increased replication will result in a xe2x80x9chyperplasticxe2x80x9d epidermis and a thickened, poorly-functioning stratum corneum which is manifested as dry, rough scales. Other common stimuli which induce epidermal cell renewal include physical removal of the stratum corneum (i.e., an example of which is tape stripping, a process where tape is applied to the skin and pulled off, removing the top layer of the stratum corneum with it) and friction (i.e., on the soles and heels of the feet), all processes which result in epidermal hyperplasia. Hydroxy acids and retinoids also induce epidermal hyperplasia at appropriate concentrations, although the mechanisms appear to be different. It is believed by many that hydroxy acids exert their effects by inducing physical exfoliation of the corneum, whereas the retinoids more likely work by interacting with cytoplasmic and nuclear binding receptors to alter gene expression. Schiltz, J. et al. xe2x80x9cRetinoic acid induces cyclic changes in epidermal thickness and dermal collagen and glycosaminoglycan biosynthesis rates,xe2x80x9d J. Invest. Dermatol. 87:663-667 (1986), describe various effects of retinoic acid on epidermal and dermal biology including cyclical epidermal thickening and hyperplasia, and dermal changes in the rates of biosynthesis of collagen and glycosaminoglycans.
With chronological age and chronic environmental exposure (notably UVA, UVB, and IR radiation), the dermis undergoes changes in structure and function which result in many of the characteristics of aged skin, including loss of elasticity, formation of wrinkles, loss of water-holding capacity, sagging, and poor microcirculation. At the molecular level, these changes have been correlated with biochemical changes in the content and structure of the extracellular matrix to which the major cells of the dermis (i.e., the fibroblasts) reside. Collagen becomes highly cross-linked and inelastic, elastin is reduced in amounts and is incorrectly distributed, and the glycosaminoglycans become reduced in amounts, which results in reduced intercellular water.
As a result of this changed architecture, the normal amounts and distribution of trace metal ions, growth factors, hormones, and cytokines becomes altered which causes the fibroblasts to become metabolically less active or quiescent. Although these cells have natural mechanisms to repair themselves and the matrix in which they reside, with age and too much damage, they are less able to repair the damage, and the condition continues to deteriorate. If the quiescent fibroblasts can be metabolically activated and stimulated to divide, they will synthesize new extracellular matrix and the old, damaged matrix will be enzymatically degraded and replaced. This process of balanced synthesis and degradation is referred to as xe2x80x9cdermal remodeling.xe2x80x9d The activation process can be accomplished in many different ways, including chemical stimulation by selected hormones, growth factors, cytokines, vitamins, botanical extracts and retinoids, or by increasing the nutrient supply (i.e., blood flow) to the tissue.
Although the mechanisms are not completely understood, it appears that physical or chemical changes to the intact stratum corneum of the skin will result in epidermal basal cell replication and subsequent increases in epidermal cell renewal. If the injury stimulus is too great, the skin will be unable to correct the damage or will xe2x80x9cover-respondxe2x80x9d in such a way as to cause extensive epidermal hyperplasia and dry, flaky, poorly-differentiated stratum corneum. If the damage stimulus is less and is well controlled, the process of epidermal replacement should result in a healthier, better-functioning epidermis and in a stratum corneum which looks and feels better, has greater capacity to hold moisture, and has fewer surface fine lines.
It is known that damage to the stratum corneum not only sets into motion natural biochemical mechanisms to repair and replace the epidermis, but disturbances in the corneum also stimulate repair and remodeling of the dermis. U.S. Pat. No. 5,720,963 to Smith (xe2x80x9cthe ""963 patentxe2x80x9d) teaches that chronic and significant disruption of the skin""s water barrier using a combination of cerebrosides, hydroxy acids, and retinoids causes chronic injury to the corneum and results in epidermal and dermal repair of the structurally-deteriorated skin if the disruption is maintained for a sufficient period of time. The mechanisms by which the combination of materials used in the ""963 patent cause increased epidermal cell renewal and chronic skin repair are entirely different from those which are involved in the current invention. Although the end benefits to the skin are similar, the ""963 patent teaches that water barrier disruption agents such as cerebrosides or organic solvents or detergents, in combination with retinoids or hydroxy acids will disrupt the corneum water barrier and stimulate basal cell replication rates. The Applicant has discovered that chronic stimulation of the normal process of desquamation by activation of at least one endogenous corneum protease will result in increased epidermal turnover and epidermal and dermal remodeling. This is not a chronic injury; instead, it is an increase in the rates of corneum shedding by one of the natural mechanisms; the increased desquamation stimulates the natural mechanisms involved in replacing the lost corneum, a process which results in beneficial skin remodeling.
In a series of peer-reviewed scientific publications, Lundstrom, A. and Egelrud, T. xe2x80x9cCell Shedding from Human Plantar Skin In Vitro: Evidence of its Dependence on Endogenous Proteolysis,xe2x80x9d J. Invest. Dermatol. 91:340-343 (1988); Egelrud, T. and Lundstrom, A., xe2x80x9cThe Dependence of Detergent-Induced Cell Dissociation in Non-Palmo-Plantar Stratum Corneum on Endogenous Proteolysis,xe2x80x9d J. Invest. Dermatol. 95: 456-459 (1990); Lundstrom, A. and Egelrud, T. xe2x80x9cStratum Corneum Chymotryptic Enzyme: A Proteinase which may be Generally Present in the Stratum Corneum and with a Possible Involvement in Desquamation,xe2x80x9d Acta Dermato-Venereol 71:471-474 (1991); investigators from the Department of Dermatology, University Hospital, Umea, Sweden, demonstrated that human stratum corneum possesses endogenous chymotryptic proteinase enzyme(s) which can be activated in vitro by a combination of the cationic surfactant N,N,-dimethyldodecyl amine oxide (DMDAO), the anionic surfactant sodium dodecyl sulfate (SDS), and the chelating agent ethylene diamine tetraacetate (EDTA). Activation of these enzymes resulted in the separation of individual corneum cells (i.e. corneocytes), a process which Egelrud""s group has proposed mimics the natural desquamation process. The Egelrud group have described the role of the endogenous chymotryptic proteinase enzyme(s) to be important in natural desquamation of the skin, but their work did not predict that stratum corneum protease activation would enhance the rates of epidermal cell renewal and set up natural epidermal and dermal biochemical mechanisms which could provide benefit to aged or environmentally-damaged skin.
Prior art physiological, chemical, or mechanical methods of increasing stratum corneum renewal rates to achieve benefit such as hydroxy acids, retinoids, barrier disrupters, tape stripping, solvent extraction, etc. all have various drawbacks, such as significant irritation to the skin, skin toxicity, the requirement of high concentrations of expensive ingredients, or of low pH. In addition, all these methods involve the invocation of damage to the skin, which sets up repair mechanisms. For most of these treatments, there will be a period of time, up to several weeks or months, during which the skin becomes irritated and after which tolerance sets in and the symptoms of irritation may decrease and/or cease. When using the method described in the present invention, these drawbacks are not encountered.
Applicant has surprisingly discovered a method of treatment and composition for aged and environmentally damaged skin that enhances the stratum corneum turnover rate by activation of at least one endogenous proteinase. The treatment, which results in skin with improved visual appearance, function, and clinical/biophysical properties, is not known in the prior art. Moreover, the novel method of treatment and compositions of the present invention accomplish this at low concentrations, at a neutral pH, in all the vehicles in which the actives have been tested, and without causing clinical irritation or chronic damage to the skin.
The features of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. Further features of the invention will be set forth in part in the description which follows and in part will be apparent from the description, or may be learned by practice of the invention.
In accordance with the purpose of the invention in one of its aspects embodied and broadly described herein, there is disclosed a method of treating skin comprising topical application to aged or damaged skin of a cosmetic composition comprising a chemically compatible combination of one or more surfactants and at least one chelating agent, in an amount effective to provide chronic stimulation of the skin""s stratum corneum turnover rate, and a reduction in the stratum corneum turnover time, by activating one or more of the skin""s endogenous corneum protease enzymes. In another aspect, the present invention includes a cosmetic treatment composition for aged or damaged skin comprising a chemically compatible combination of one or more surfactants and at least one chelating agent, in an amount effective to provide chronic stimulation of the skin""s stratum corneum turnover rate, and a reduction in the stratum corneum turnover time, by activating one or more of the skin""s endogenous corneum protease enzymes.
Additional aspects of the invention will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The purposes and features of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
The present invention provides a novel method of treatment and a novel composition for treating aged and environmentally damaged or deteriorated skin. The present invention provides a method of treating skin comprising topical application to damaged skin of a cosmetic composition in an amount effective to provide a chronic, increased replacement rate of the skin""s stratum corneum by means of corneum protease activation, wherein the increased replacement rate is effective to induce repair, replacement, and remodeling of the stratum corneum, epidermis, and dermis of the skin and improvements in the appearance, function, and aging properties of the skin.
According to the present invention, xe2x80x9cincreased replacement ratexe2x80x9d and xe2x80x9cstimulation of the skin""s stratum corneum turnover ratexe2x80x9d includes any rate of stratum corneum or epidermal turnover which is greater than that of the untreated skin on the same site of the same individual. Typically, this increase in turnover rate, or reduction in turnover time, can range from about 1% to about 40%. Preferably turnover rate is increased by about 25%. There are many different ways in which epidermis and stratum corneum turnover rate can be measured, including but not restricted to assays to measure dansyl chloride disappearance, dihydroxy acetone staining disappearance, or use of radioactive thymidine to measure basal cell labeling index. Chronic stimulation of the stratum corneum turnover rate refers to the repeated, or constant stimulation occurring with regular treatment of the skin with the composition of the present invention.
Similarly, xe2x80x9creduction in skin""s stratum corneum turnover timexe2x80x9d is the resulting decrease in the time needed for the shedding of the skin layer. The turnover time reduction can range from about 1% to about 40%, preferably the time reduction is about 25%.
xe2x80x9cCorneum protease activationxe2x80x9d refers to a stimulation, above that of untreated skin, of one or more of the endogenous stratum corneum chymotryptic protease enzymes believed to be involved in the natural desquamation process of corneocyte shedding and subsequent stratum corneum turnover.
The effectiveness of the method of the present invention in providing skin anti-aging benefits can be measured by a number of ways. Each of these strategies for evaluating the effectiveness of the invention can be used independently or together by one skilled in the art. The method is effective when it decreases stratum corneum turnover time by from about 1% to about 40%, preferably by at least about 25%. It is also effective when it reduces TEWL by from about 0% to about 100%, preferably by at least about 1%. It is further effective when it decreases canthus skin roughness by from about 1% to about 60%, preferably by at least about 9%. The method is effective when it decreases the number of wrinkles on the canthus by from about 1% to about 60%, preferably by at least about 9%. It is also effective when it increases skin moisture on the canthus by from about 1% to about 90%, preferably by at least about 21%. It is effective when it increases skin moisture on the cheek by from about 1% to about 90%, preferably by at least about 14%.
The cosmetic composition should be topically applied regularly to whatever skin area requires treatment with the frequency and in the amount necessary to achieve the desired results. Preferably, the cosmetic composition is applied at least once per day, most preferably twice per day. The frequency of treatment depends on the degree of damage or deterioration of the skin, the responsiveness of the user""s skin, the strength of the active ingredients in the cosmetic product, the effectiveness of the vehicle used to deliver the active ingredients into the stratum corneum, the ease with which the formula is removed by physical contact with clothing or it""s removal by sweat or other intrinsic or extrinsic fluids, and the convenience to the user""s lifestyle. Typical concentrations of relatively simple biochemically active substances such as the novel treatment composition described herein can range from about 0.01% to about 5.0% by weight based on the total weight of the cosmetic composition, and the formula should be applied to the skin at a rate equal to from about 1.0 mg/cm2 of skin to about 20.0 mg/cm2 of skin. Preferably, the formula should contain from about 0.39% to about 0.78% by weight based on the total weight of the cosmetic composition. Most preferably, the formula should contain about 0.78% active ingredients and be applied to the skin at a rate of about 5.0 mg/cm2 of skin.
The cosmetic composition of the present invention comprises safe and effective amounts of one or more surfactants and at least one chelating agent. Use of these combinations of materials will result in an activation of one or more of the resident stratum corneum protease chymotryptic enzymes, which causes a loss of adherence between corneocytes, thus allowing them to be shed at a faster rate. While the mechanism or mechanisms of this activation process are unknown, we speculate that the surfactants could cause one or more of the following changes, including conformational changes in the enzyme, uncovering of the active site of the enzyme, or removal of lipids or other adherent substances from the enzyme. The chelating agent could somehow regulate the concentration of a metal cation which may be required for activity such as Ca++, Mg++, Sr++, or Mn++. The surfactants can be selected from any natural or synthetic surfactants suitable for use in cosmetic compositions and can be cationic, anionic, zwitterionic, non-ionic, or mixtures thereof. (See Rosen, M., xe2x80x9cSurfactants and Interfacial Phenomena,xe2x80x9d Second Edition, John Wiley and Sons, New York, 1988, Chapter 1, pages 4-31). Suitable cationic surfactants can include, but are not limited to DMDAO or other amine oxides, long-chain primary amines, diamines and polyamines and their salts, quaternary ammonium salts, polyoxyethylenated long-chain amines, and quaternized polyoxyethylenated long-chain amines. Suitable anionic surfactants can include, but are not limited to SDS, salts of carboxylic acids (i.e. soaps), salts of sulfonic acids, salts of sulfuric acid, phosphoric and polyphosphoric acid esters, alkylphosphates, monoalkyl phosphate (MAP), and salts of perfluorocarboxylic acids. Suitable zwitterionic surfactants can include but are not limited to cocoamidopropyl hydroxysultaine (CAPHS) and others which are pH-sensitive and require special care in designing the appropriate pH of the formula (i.e. alkylaminopropionic acids, imidazoline carboxylates, and betaines) or those which are not pH-sensitive (i.e. sulfobetaines, sultaines). Suitable non-ionic surfactants can include but are not limited to alkylphenol ethoxylates, alcohol ethoxylates, polyoxyethylenated polyoxypropylene glycols, polyoxyethylenated mercaptans, long-chain carboxylic acid esters, alkonolamides, tertiary acetylenic glycols, polyoxyethylenated silicones, N-alkylpyrrolidones, and alkylpolyglycosidases. Any combination of surfactants is acceptable. Preferably, the surfactant includes at least one anionic and one cationic surfactant, or at least one cationic and one zwitterionic surfactant which are compatible, e.g., do not form complexes which precipitate appreciably when mixed. Most preferably, the surfactant includes DMDAO and SDS, or DMDAO and MAP. Applicants believe that SDS and MAP are interchangeable in the present invention.
The chelating agent can be any chelating agent suitable for use in a cosmetic composition. Suitable chelating agents can include, but are not limited to any natural or synthetic chemical which has the ability to bind divalent cationic metals such as Ca++, Mn++, or Mg++. Preferably, the chelating agent is selected from EDTA, disodium EDTA, EGTA, citric acid, or dicarboxylic acids. Most preferably, the chelating agent is EDTA.
Where the cosmetic composition contains a cationic surfactant such as DMDAO, the percent of such surfactant in the composition is from about 0.01% to about 5.0% by weight based on the total weight of the cosmetic composition, preferably from about 0.18% to about 0.36% and most preferably about 0.36%. Where the cosmetic composition contains an anionic surfactant such as SDS or MAP, the percent of such surfactant in the composition is from about 0.01% to about 5.0% by weight based on the total weight of the cosmetic composition, preferably from about 0.06% to about 0.12% and most preferably about 0.12%. The cosmetic composition includes a chelating agent such as EDTA at from about 0.01% to about 5.0% by weight based on the total weight of the cosmetic composition, preferably from about 0.15% to about 0.30% and most preferably about 0.30%.
While various combinations of surfactant and chelating agents may be used, the cosmetic composition of the present invention most preferably includes a combination of DMDAO/SDS/EDTA, alternatively the same concentration of MAP can substitute for the SDS. In the context of the present invention,a preferred composition is 0.18% DMDAO, 0.06% SDS and 0.15% EDTA by weight based on the total weight of the cosmetic composition. This composition has been designated as a 1xc3x97concentration of the active ingredients. Concentration levels for this combination can range from between about 0.1xc3x97 to about 10xc3x97, preferably from about 1xc3x97 to about 3xc3x97 and most preferably about 2xc3x97. The present invention provides aged or environmentally-damaged skin with anti-aging benefits which are comparable to those achieved with hydroxy acids and retinoids. Furthermore, the indicated combinations of DMDAO/SDS/EDTA are non-toxic, and non-irritating. In this context, xe2x80x9cnon-toxicxe2x80x9d means that these materials, at the recommended concentrations and usage rates, do not damage living skin cells and xe2x80x9cnon-irritatingxe2x80x9d means that there are no periods of time during their use when these materials cause classical clinical irritation characterized by immunological reactions and/or burning, itching, stinging, erythema, or scaling of the skin. In marked contrast, efficacious levels of retinoids and hydroxy acids can cause the skin to experience all of these symptoms of irritation during the initial stages of treatment, and can persist indefinitely.
The indicated combinations of DMDAO/SDS/EDTA are effective in all suitable cosmetic vehicles, including emulsions, creams, lotions, solutions (both aqueous and hydro-alcoholic), anhydrous bases (such as lipsticks and powders), gels, and ointments. One skilled in the art would generally recognize these and other standard cosmetic vehicles that can be used in the present invention. Thus, the present invention may be formulated with a variety of cosmetic vehicles in addition to those described in the Examples below. Variations and other appropriate vehicles will be apparent to the skilled artisan and are appropriate for use in the present invention. Preferably, the cosmetic vehicle is selected from oil-in-water emulsions, hydro-alcoholic solutions, and encapsulated beads in anhydrous systems. Most preferably, the vehicle is an oil-in-water emulsion. Such emulsions and their compositions and methods of making are well known in the art. It is important, however, that the concentrations and combinations of the surfactants and chelating agents be selected in such a way that the combinations are chemically compatible and do not form complexes which precipitate from the finished product.
The composition of the present invention can be used in many cosmetic products including, but not limited to, moisturizing cream, skin benefit creams and lotions, gels, ointments, foundation, night cream, lipstick, cleansers, toners, masks, and color cosmetic products. The composition is most preferably used in anti-aging products for the face and other body parts, most especially leave-on products,
Products according to the present invention in which humectant properties are desired may include amino acids, chondroitin sulfate, diglycerin, erythritol, fructose, glucose, glycerin, glycerol, glycol, 1,2,6-hexanetriol, honey, hyaluronic acid, hydrogenated honey, hydrogenated starch hydrolysate, inositol, lactitol, maltitol, maltose, mannitol, natural moisturization factor, PEG-15 butanediol, polyglyceryl sorbitol, salts of pyrollidone carboxylic acid, potassium PCA, propylene glycol, sodium glucuronate, sodium PCA, sorbitol, sucrose, trehalose, urea, and xylitol.
Products according to the present invention in which antioxidant properties are desired may include acetyl cysteine, ascorbic acid, ascorbic acid polypeptide, ascorbyl dipalmitate, ascorbyl methylsilanol pectinate, ascorbyl palmitate, ascorbyl stearate, BHA, BHT, t-butyl hydroquinone, cysteine, cysteine HCI, diamylhydroquinone, di-t-butylhydroquinone, dicetyl thiodipropionate, dioleyl tocopheryl methylsilanol, disodium ascorbyl sulfate, distearyl thiodipropionate, ditridecyl thiodipropionate, dodecyl gallate, erythorbic acid, esters of ascorbic acid, ethyl ferulate, ferulic acid, gallic acid esters, hydroquinone, isooctyl thioglycolate, kojic acid, magnesium ascorbate, magnesium ascorbyl phosphate, methylsilanol ascorbate, natural botanical anti-oxidants such as green tea or grape seed extracts, nordihydroguaiaretic acid, octyl gallate, phenylthioglycolic acid, potassium ascorbyl tocopheryl phosphate, potassium sulfite, propyl gallate, quinones, rosmarinic acid, sodium ascorbate, sodium bisulfite, sodium erythorbate, sodium metabisulfite, sodium sulfite, superoxide dismutase, sodium thioglycolate, sorbityl furfural, thiodiglycol, thiodiglycolamide, thiodiglycolic acid, thioglycolic acid, thiolactic acid, thiosalicylic acid, tocophereth-5, tocophereth-10, tocophereth-12, tocophereth-18, tocophereth-50, tocopherol, tocophersolan, tocopheryl acetate, tocopheryl linoleate, tocopheryl nicotinate, tocopheryl succinate, and tris(nonylphenyl)phosphite.
Products according to the present invention in which moisturizing properties are desired may include acetylated lanolin, acetylated lanolin alcohol, acrylates/C10-30 alkyl acrylate crosspolymer, acrylates copolymer, alanine, algae extract, aloe barbadensis, aloe-barbadensis extract, aloe barbadensis gel, althea officinalis extract, aluminum starch octenylsuccinate, aluminum stearate, apricot (prunus armeniaca) kernel oil, arginine, arginine aspartate, arnica montana extract, ascorbic acid, ascorbyl palmitate, aspartic acid, avocado (persea gratissima) oil, barium sulfate, barrier sphingolipids, butyl alcohol, beeswax, behenyl alcohol, beta-sitosterol, BHT, birch (betula alba) bark extract, borage (borago officinalis) extract, 2-bromo-2-nitropropane-1,3-diol, butcherbroom (ruscus aculeatus) extract, butylene glycol, calendula officinalis extract, calendula officinalis oil, candelilla (euphorbia cerifera) wax, canola oil, caprylic/capric triglyceride, cardamon (elettaria cardamomum) oil, carnauba (copernicia cerifera) wax, carrageenan (chondrus crispus), carrot (daucus carota sativa) oil, castor (ricinus communis) oil, ceramides, ceresin, ceteareth-5, ceteareth-12, ceteareth-20, cetearyl octanoate, ceteth-20, ceteth-24, cetyl acetate, cetyl octanoate, cetyl palmitate, chamomile (anthemis nobilis) oil, cholesterol, cholesterol esters, cholesteryl hydroxystearate, citric acid, clary (salvia sclarea) oil, cocoa (theobroma cacao) butter, coco-caprylate/caprate, coconut (cocos nucifera) oil, collagen, collagen amino acids, corn (zea mays)oil, fatty acids, decyl oleate, dextrin, diazolidinyl urea, dimethicone copolyol, dimethiconol, dioctyl adipate, dioctyl succinate, dipentaerythrityl hexacaprylate/hexacaprate, DMDM hydantoin, DNA, erythritol, ethoxydiglycol, ethyl linoleate, eucalyptus globulus oil, evening primrose (oenothera biennis) oil, fatty acids, tructose, gelatin, geranium maculatum oil, glucosamine, glucose glutamate, glutamic acid, glycereth-26, glycerin, glycerol, glyceryl distearate, glyceryl hydroxystearate, glyceryl laurate, glyceryl linoleate, glyceryl myristate, glyceryl oleate, glyceryl stearate, glyceryl stearate SE, glycine, glycol stearate, glycol stearate SE, glycosaminoglycans, grape (vitis vinifera) seed oil, hazel (corylus americana) nut oil, hazel (corylus avellana) nut oil, hexylene glycol, honey, hyaluronic acid, hybrid safflower (carthamus tinctorius) oil, hydrogenated castor oil, hydrogenated coco-glycerides, hydrogenated coconut oil, hydrogenated lanolin, hydrogenated lecithin, hydrogenated palm glyceride, hydrogenated palm kernel oil, hydrogenated soybean oil, hydrogenated tallow glyceride, hydrogenated vegetable oil, hydrolyzed collagen, hydrolyzed elastin, hydrolyzed glycosaminoglycans, hydrolyzed keratin, hydrolyzed soy protein, hydroxylated lanolin, hydroxyproline, imidazolidinyl urea, iodopropynyl butylcarbamate, isocetyl stearate, isocetyl stearoyl stearate, isodecyl oleate, isopropyl isostearate, isopropyl lanolate, isopropyl myristate, isopropyl palmitate, isopropyl stearate, isostearamide DEA, isostearic acid, isostearyl lactate, isostearyl neopentanoate, jasmine (jasminum officinale) oil, jojoba (buxus chinensis) oil, kelp, kukui (aleurites moluccana) nut oil, lactamide MEA, laneth-16, laneth-10 acetate, lanolin, lanolin acid, lanolin alcohol, lanolin oil, lanolin wax, lavender (lavandula angustifolia) oil, lecithin, lemon (citrus medica limonum) oil, linoleic acid, linolenic acid, macadamia ternifolia nut oil, magnesium stearate, magnesium sulfate, maltitol, matricaria (chamomilla recutita) oil, methyl glucose sesquistearate, methylsilanol PCA, microcrystalline wax, mineral oil, mink oil, mortierella oil, myristyl lactate, myristyl myristate, myristyl propionate, neopentyl glycol dicaprylate/dicaprate, octyldodecanol, octyldodecyl myristate, octyldodecyl stearoyl stearate, octyl hydroxystearate, octyl palmitate, octyl salicylate, octyl stearate, oleic acid, olive (olea europaea) oil, orange (citrus aurantium dulcis) oil, palm (elaeis guineensis) oil, palmitic acid, pantethine, panthenol, panthenyl ethyl ether, paraffin, PCA, peach (prunus persica) kernel oil, peanut (arachis hypogaea) oil, PEG-8 C12-18 ester, PEG-15 cocamine, PEG-150 distearate, PEG-60 glyceryl isostearate, PEG-5 glyceryl stearate, PEG-30 glyceryl stearate, PEG-7 hydrogenated castor oil, PEG-40 hydrogenated castor oil, PEG-60 hydrogenated castor oil, PEG-20 methyl glucose sesquistearate, PEG40 sorbitan peroleate, PEG-5 soy sterol, PEG-10 soy sterol, PEG-2 stearate, PEG-8 stearate, PEG-20 stearate, PEG-32 stearate, PEG40 stearate, PEG-50 stearate, PEG-100 stearate, PEG-150 stearate, pentadecalactone, peppermint (mentha piperita) oil, petrolatum, phospholipids, polyamino sugar condensate, polyglyceryl-3 diisostearate, polyquaternium-24, polysorbate 20, polysorbate 40, polysorbate 60, polysorbate 80, polysorbate 85, potassium myristate, potassium palmitate, potassium sorbate, potassium stearate, propylene glycol, propylene glycol dicaprylate/dicaprate, propylene glycol dioctanoate, propylene glycol dipelargonate, propylene glycol laurate, propylene glycol stearate, propylene glycol stearate SE, PVP, pyridoxine dipalmitate, quaternium-15, quaternium-18 hectorite, quaternium-22, retinol, retinyl palmitate, rice (oryza sativa) bran oil, RNA, rosemary (rosmarinus officinalis) oil, rose oil, safflower (carthamus tinctorius) oil, sage (salvia officinalis) oil, salicylic acid, sandalwood (santalum album) oil, serine, serum protein, sesame (sesamum indicum) oil, shea butter (butyrospermum parkii), silk powder, sodium chondroitin sulfate, sodium DNA, sodium hyaluronate, sodium lactate, sodium palmitate, sodium PCA, sodium polyglutamate, sodium stearate, soluble collagen, sorbic acid, sorbitan laurate, sorbitan oleate, sorbitan palmitate, sorbitan sesquioleate, sorbitan stearate, sorbitol, soybean (glycine soja) oil, sphingolipids, squalane, squalene, stearamide MEA-stearate, stearic acid, stearoxy dimethicone, stearoxytrimethylsilane, stearyl alcohol, stearyl glycyrrhetinate, stearyl heptanoate, stearyl stearate, sunflower (helianthus annuus) seed oil, sweet almond (prunus amygdalus dulcis) oil, synthetic beeswax, tocopherol, tocopheryl acetate, tocopheryl linoleate, tribehenin, tridecyl neopentanoate, tridecyl stearate, triethanolamine, tristearin, urea, vegetable oil, water, waxes, wheat (triticum vulgare) germ oil, and ylang ylang (cananga odorata) oil.
Products according to the present invention in which ultraviolet light (UVA and UVB) absorbing properties are desired may include benzophenone, benzophenone-1, benzophenone-2, benzophenone-3, benzophenone-4 benzophenone-5, benzophenone-6, benzophenone-7, benzophenone-8, benzophenone-9, benzophenone-10, benzophenone-11, benzophenone-12, benzyl salicylate, butyl PABA, cinnamate esters, cinoxate, DEA-methoxycinnamate, diisopropyl methyl cinnamate, ethyl dihydroxypropyl PABA, ethyl diisopropylcinnamate, ethyl methoxycinnamate, ethyl PABA, ethyl urocanate, glyceryl octanoate dimethoxycinnamate, glyceryl PABA, glycol salicylate, homosalate, isoamyl p-methoxycinnamate, PABA, PABA esters, Parsol 1789, and isopropylbenzyl salicylate.
Additional skin care preparation ingredients include skin lightening agents (e.g. kojic acid, hydroquinine, ascorbic acid and derivatives, retinoids, etc.), hydroxy acids (e.g. lactic acid, salicylic acid, etc.), emollients (e.g. esters, fatty acids, etc.), vitamins (i.e. A, C, E, K, etc.), trace metals (e.g. zinc, calcium, selenium, etc.), anti-irritants (e.g. steroids, non-steroidal anti-inflammatories, etc.), antimicrobial agents (e.g. triclosan, etc.), botanical extracts (e.g. aloe vera, chamomile, cucumber extract, ginkgo bibloba, ginseng, rosemary, etc.), dyes and color ingredients (e.g. DandC blue no. 4, DandC green no. 5, DandC orange no. 4, DandC red no. 17, DandC red no. 33, DandC violet no. 2, DandC yellow no. 10, DandC yellow no. 11, DEA-cetyl phosphate), preservatives (e.g. BHA), emollients (i.e. organic esters, fatty acids, lanolin and its derivatives, plant and animal oils and fats, di- and triglycerides, etc.), antiirritants (i.e., steroids, nonsteroidal antiinflammatories, glycyrrhizates, etc.), antimicrobial agents (i.e., triclosan, ethanol, etc.), and fragrances (natural and artificial).
One skilled in the art will understand that the terms xe2x80x9cmixturexe2x80x9d and xe2x80x9cmixingxe2x80x9d in this patent are used in the broad sense of the words, with the term xe2x80x9cmixingxe2x80x9d including, but not limited to, stirring, blending, dispersing, milling, homogenizing, and other similar methods.
The cosmetic composition of the present invention is effective at pH values between about 2.5 and about 10.0. Preferably, the pH of the composition is between the following pH ranges: about 5.5 and about 8.5, about 5 to about 10, about 5 to about 9, about 5 to about 8, about 3 to about 10, about 3 to about 9, about 3 to about 8, and about 3 to about 8.5. Most preferably, the pH is about 8. One of ordinary skill in the art may add appropriate pH adjusting ingredients to the compositions of the present invention to adjust the pH to an acceptable range.

Treatment and composition for achieving skin anti-aging benefits by corneum protease activation


A switching power supply circuit includes a direct current (DC) power supply input, a first transistor, a capacitor, a first resistor, a second resistor, a switching circuit including a second transistor, and a first transformer including a first primary winding and a secondary winding. The DC power supply input is connected to a drain electrode of the first transistor via the capacitor. A gate electrode of the first transistor is connected to ground via the first resistor, and connected to the drain electrode of the first transistor via the second resistor. The DC power supply input is connected to a source electrode of the first transistor via the primary winding. The source electrode of the first transistor is grounded via the second transistor. The secondary winding is structured and arranged to drive a load circuit.

1. Technical Field
The present disclosure relates to a switching power supply circuit and a method for driving a switching power supply circuit.
2. Description of Related Art
Switching power supply circuits, exhibiting superior linear characteristics, consuming minimum power, converting electrical power efficiently, and performing steadily, are preferred for use in LCD TVs, displays, and other consumer devices.
FIG. 3 shows a commonly used switching power supply circuit. The switching power supply circuit 10 includes a first rectifying and filtering circuit 11, a snubber circuit 13, a transformer 14, a second rectifying and filtering circuit 12, a switching circuit 15, and a rectifying diode 16. The switching circuit 15 includes a pulse width modulation integrated circuit (PWM IC) 151, a transistor 152, and a resistor 155. The PWM IC 151 includes a voltage input 153 for receiving an operating voltage, and a pulse output 154 for transmitting a generated pulse signal to a gate electrode of the transistor 152.
The first rectifying and filtering circuit 11 includes two inputs 113, 114 structured and arranged to receive an external alternating current (AC) voltage such as a 220V AC voltage, a full-bridge rectifying circuit 111 structured and arranged to convert the 220V AC voltage to a first direct current (DC) voltage, a first filtering capacitor 112 structured and arranged to stabilize the first DC voltage, and a first output 115 structured and arranged to provide the first DC voltage to the transformer 14. Two inputs of the full-bridge rectifying circuit 111 serve as the two inputs 113, 114. A positive output of the full-bridge rectifying circuit 111 serves as the first output 115. A negative output of the full-bridge rectifying circuit 111 is grounded. The first filtering capacitor 112 is connected between the first output 115 and ground.
The transformer 14 includes a primary winding 141, an auxiliary winding 142, and a secondary winding 143. The primary winding 141 is electrically connected in parallel with the snubber circuit 13. One terminal "a" of the primary winding 141 is connected to the first output 115, and the other terminal "b" of the primary winding 141 is connected to a drain electrode of the transistor 152. A source electrode of the transistor 152 is grounded via the resistor 155. The gate electrode of the transistor 152 is connected to the pulse output 154 of the PWM IC 151.
One terminal of the auxiliary winding 142 is grounded. The other terminal of the auxiliary winding 142 is connected to the voltage input 153 of the PWM IC 151 via an anode and a cathode of the rectifying diode 16 in series.
The second rectifying and filtering circuit 12 includes an inductor 121, a storage capacitor 122, a second filtering capacitor 123, a rectifying diode 124, and a second output 125. One terminal "c" of the secondary winding 143 is connected to the second output 125 via an anode and a cathode of the rectifying diode 124 and the inductor 121 in series. The other terminal "d" of the secondary winding 143 is grounded. The second filtering capacitor 123 is connected between the second output 125 and ground. The storage capacitor 122 is connected between the cathode of the rectifying diode 124 and ground.
The switching power supply circuit 10 operates as follows:
The external AC voltage is provided to the two inputs 113, 114 of the first rectifying and filtering circuit 11, and is converted to the first DC voltage by the first rectifying and filtering circuit 11. The first DC voltage is provided to the primary winding 141. The auxiliary winding 142 is induced by the primary winding 141, generates an operating voltage, and provides the operating voltage to the voltage input 153 of the PWM IC 151 via the rectifying diode 16. Thus the PWM IC 151 generates the pulse signal for switching the transistor 152 on or off.
When the transistor 152 is switched on, a first current path is formed sequentially through the first output 115, the primary winding 141, the transistor 152, and the resistor 155. A first current I is formed when the first DC voltage provided to the first output 115 is connected to ground via the first current path. The first current I through the first current path increases linearly until electromagnetic induction generated in the primary winding 141 reaches a predetermined maximum threshold. Thus a voltage across the primary winding 141 is generated such that a potential of the terminal "a" is higher than that of the terminal "b". The secondary winding 143 is induced by the increasing first current I to generate a first induced voltage such that a potential of the terminal "c" is higher than that of the terminal "d". The rectifying diode 124 and the inductor 121 convert the first induced voltage to a second DC voltage, and provide the second DC voltage to a load circuit (not shown) via the second output 125.
When the transistor 152 is switched off, the snubber circuit 13 gradually absorbs and decreases the first current I. The secondary winding 143 is induced by the decreasing first current I to generate a second induced voltage such that the potential of the terminal "d" is higher than that of the terminal "c". Thus the rectifying diode 124 is switched off, and no voltage is outputted from the second output 125.
The switching power supply circuit 10 does not utilize the decreasing first current I to generate the second DC voltage when the transistor 152 is switched off and the first current I is absorbed by the snubber circuit 13. Thus, the switching power supply circuit 10 lacks efficiency.
It is thus desirable to provide a switching power supply circuit which can overcome the described limitations.

Switching power supply circuit and driving method thereof


A technique for centralized processing of oilfield or waterfield engineering data for design and analysis from distributed locations is disclosed. In one aspect, the invention includes a method comprising: acquiring a plurality of oilfield or waterfield data; establishing a communications link between a client computing device to a server computing device; inputting data from the client computing device to the server computing device; processing the data at the server computing device; and communicating the results to the client computing device. In a second aspect, the invention includes a computing system, comprising: a client computing device; a server computing device interconnected with the client computing device; and an analysis tool resident on the server. The analysis tool includes a calculation engine capable of analyzing the data entered from the client computing device; and a plurality of program utilities for use by the calculation engine in analyzing the data.

1. Field of the Invention
The present invention relates generally to hydrocarbon (petroleum and natural gas) production from wells drilled in the earth, and, more particularly, the centralized processing of oilfield or waterfield engineering data for the design and analysis of procedures associated with such drilling and production from distributed locations.
2. Description of the Related Art
Hydrocarbon production typically involves drilling a well through the earth""s subsurface to a hydrocarbon deposit and then extracting the hydrocarbons. Drilling a well in the subsurface is expensive, which limits the number of wells that can be economically drilled. Also, even the most skilled and talented people using the most sophisticated tools and techniques will occasionally drill xe2x80x9cdry holes,xe2x80x9d i.e., wells that do not produce. The relatively high expense, the limited number of wells, and the occasional failures drive producers to more quickly, accurately, and efficiently locate, and extract hydrocarbon deposits. Producers have consequently developed an extensive body of technology surrounding the location and production of hydrocarbons. Different parts of this technology deal with, for example, measuring physical and/or electrical characteristics of geological formations, facilitating the drilling of bore holes, and stimulating production. Typically, these areas of the technology intersect.
Consider, for instance, a production stimulation technique known as xe2x80x9cfracturing.xe2x80x9d The rate of flow, or xe2x80x9cproductionxe2x80x9d of hydrocarbon from a geologic formation depends on numerous factors. One factor is the radius of the bore hole. As the radius of the bore hole increases, the production rate increases, everything else being equal. Another factor, related to the first, is the flowpaths available to the migrating hydrocarbon. The expense of drilling a well only generally increases as the size of the hole increases. However, a larger hole imparts greater instability to the geologic formation. This increased instability increases the chances that the formation will shift, and therefore damage the well bore or, at worst, collapse the well bore. So, while a larger bore hole will, in theory, increase hydrocarbon production, it is impractical and carries a significant downside. Yet, a fracture or large crack within the producing zone of the geologic formation, originating at and radiating from the well bore, can actually increase the xe2x80x9ceffectivexe2x80x9d (as opposed to xe2x80x9cactualxe2x80x9d) well bore radius. The well then behaves (in terms of production rate) as if the entire well bore radius were much larger.
Such a fracture can be intentionally created to stimulate production, and this technique is known as fracturing. Hydraulic fracturing involves literally breaking or fracturing a portion of the surrounding strata, by injecting a specialized fluid into the well bore directed at the face of the geologic formation at pressures sufficient to initiate and/or extend a fracture in the formation. More particularly, a fluid is injected through a well bore. The fluid exits through perforations in the well casing and is directed against the face of the formation at a pressure and flow rate sufficient to overcome the in situ stress (a.k.a. the xe2x80x9cminimum principal stressxe2x80x9d) and to initiate and/or extend a fracture(s) into the formation. Actually, what is created by this process is not always a single fracture, but a fracture zone, i.e., a zone having multiple fractures, or cracks in the formation, through which hydrocarbon can more readily flow to the well bore.
In practice, fracturing a well is a highly complex operation performed with the complex orchestration of over a dozen large trucks, roughly the same number of highly skilled engineers or technicians, a mobile laboratory for real-time quality assurance, and powerful integrated computers that monitor pumping rates, downhole pressures, etc. During a typical fracturing job, over 350,000 pounds of fluid will be pumped at extraordinarily high pressures (exceeding the minimum principal stress) down a well, to a pinpoint location, often thousands of feet below the earth""s surface. Moreover, during the fracturing process, constant iterations of fluid level, pumping rates, and pumping times are performed to maximize the fracture zone, and minimize the damage to the formation.
Consider also, the use of drilling fluids known as muds. A drilling fluid or xe2x80x9cmudxe2x80x9d is typically continuously circulated from the surface down to the bottom of a well bore being drilled and back to the surface again. The mud has several functions, one of them being to transport cuttings removed by the drill bit up to the surface where they are separated from the mud. A second function is to form a filtercake on the walls of the bore hole so as to avoid a collapse of the bore hole. However, the filtercakes formed on the bore hole walls can cause damage to the reservoir and impair productivity unless they are removed or bypassed after drilling. The process of filtercake removal in open hole wells is frequently called xe2x80x9cmud clean up.xe2x80x9d
The data needed to properly design well procedures, such as fracturing or mud clean up treatments is acquired by logging or other methods of measuring reservoir properties, including, but not limited to, coring, fluid sampling, or pressure testing. This data is then analyzed and used in a variety of engineering calculations to determine the best methods of completing, producing, or stimulating a particular well. The final choice of completion or stimulation method may have a large effect on the ultimate producing efficiency of the well and its economic success. During the productive life of a well or reservoir, the data may also be used to design remedial treatments or changes in production methods.
The efficient production of hydrocarbons requires constant monitoring and maintenance of the producing wells and reservoir. Proper completion procedures and equipment are needed to insure adequate contact between the well and the reservoir. Stimulation treatments may be required to improve productivity from or infectivity into the reservoir for production enhancement. The design of well and reservoir treatments involves many steps, such as problem identification, appropriate treatment selection, fluid selection, placement process determination, and volume and rate calculations. Specifying mechanical equipment may also be required. After implementation, the effects of the various treatments are often analyzed to determine results and to improve future treatments. Many of the steps in design and analysis require some type of calculation to be made. The production, operations, reservoir, or service provider engineer at each field location typically performs these calculations. Frequently, the calculations involve the use of equations that are very well known in the art.
Large international companies typically have multiple field locations where such design and analyses are conducted on a routine basis. The engineers at each location may have their own method of making a particular calculation, and thus the same type of analysis may vary among the locations. For instance, an engineer at one location might perform an analysis using a software implemented analysis tool that embodies certain assumptions about the data operated on or employs a particular set of units of measurement. An engineer at a second location might perform the very same analysis using an analysis tool that embodies a second set of assumptions different from those in the first analysis tool and/or different units of measurement.
Each location or engineer may therefore have their own method of performing some particular analysis. For a large corporation, this means that many people are performing the same analysis in myriad ways. This is especially true when new products are introduced. The methodology for treatment design calculations is passed on in schools and by word or mouth within the organization. Each transmittal of the information increases the risk of misinterpretation and corruption of the calculation. Perhaps even worse, when one engineer borrows or trades for another""s tool, that engineer is not aware of the assumptions or the units of measurement used by the tool. This leads to significant and, if not caught in time, costly errors.
This distributed analysis impacts the marketing of oilfield or waterfield services by oilfield or waterfield service providers. Oilfield or waterfield service providers frequently provide services where they analyze data for their clients. Knowing which of the provider""s engineers are performing what calculations can help a provider market the services employing those calculations. However, the distributed nature of the current configuration makes this difficult. Although tracking new product usage typically occurs after release, the distribution of the usage hampers thorough, accurate collection of this information. Frequently, this information is obtained only after someone in the field has a problem and contacts the design team for help. This type of information consequently is of little assistance in marketing.
The present invention is directed to resolving, or at least reducing, one or all of the problems mentioned above.
The invention is a technique for centralized processing of oilfield engineering data for design and analysis from distributed locations.
In one aspect, the invention includes a method comprising: acquiring a plurality of oilfield or waterfield data; establishing a communications link between a client computing device to a server computing device; inputting data from the client computing device to the server computing device; processing the data at the server computing device; and communicating the results to the client computing device.
In a second aspect, the invention includes a computing system, comprising: a client computing device; a server computing device interconnected with the client computing device; and an analysis tool resident on the server. The analysis tool includes a calculation engine capable of analyzing the data entered from the client computing device; and a plurality of program utilities for use by the calculation engine in analyzing the data.

Method and apparatus for centralized processing of oilfield or waterfield engineering data for design and analysis from distributed locations


The present invention concerns a modular and adjustable staircase, prefabricated, destined to be installed in a rigid manner, and having at least one side which is equipped with a stiffener (1). Per stair and per side having a stiffener (1), a single element of the staircase, which is a crosspiece equipped with a heel (7a), of a shim (6), must be adjusted or is predetermined is order to obtain the desired stair height.

The present invention concerns a modular and adjustable staircase, prefabricated, designed to be installed in a rigid manner, and having at least one side which is equipped with a stiffener. Per stair and per side having a stiffener, a single element of the staircase, which is a cross piece with a heel, or a shim, must be adjusted or is predetermined in order to obtain the stair height desired. The shim is an element that is placed under the bottom side of the crosspiece to adjust the height of the step. The crosspiece with heel is a one piece element which likewise determines the height of the step.
Definitions of the terms used in the description and the claims:
floor to floor spacing: the space which separates the levels of a storey, that is, the vertical distance between the upper floor and the lower floor of the place where the present invention is to be installed.
rear of a stair: the part opposite the nosing.
tread: the horizontal spacing between two stair nosings, measured along the line of stride.
width of a stair: horizontal spacing which is perpendicular to the tread, measured between the stair extremities.
height of a stair: vertical distance between the level of the lower floor and the first stair, or between two consecutive stairs, or between the last stair and the level of the upper floor.
constant stair height: height obtained by dividing the floor to floor spacing by the number of stairs plus one.
The present invention, tending to bring improvements to patent #92 06170 published under #2691 489, differs from the prior techniques by its possibility for adjusting the heights of stairs and/or the tread and/or the width of each stair, which makes the staircase multi-purpose and suitable for installing in spaces with dissimilar volumes.
Thus the installation of the staircase can form only constant stair heights. Most of the known manufactured staircases require a staircase starting base which can be cut off at the top; which, compared to the vertical spacing of the other stairs shows a disparity in height which is detrimental to the climbing or descending cadence of the user. The base makes the structure uncomfortable and dangerous because of this disparity in height.
Patent DE-A-2619804 filed by the Carl Rehfeldt cement factory, describes several configurations for prefabricated staircases designed to be built using fiberglass-reinforced concrete. Contrary to the present invention, the various configurations described, as well as their manner of production, allow neither an adjustment of the geometry of a type of element of the prefabricated staircase, nor a choice of position and orientation of certain of the elements of the staircase in relation to one other in order to result in a possible in situ adjustment of the height and tread of the stairs, whereas the present invention allows all of that.


A semiconductor device having a fuse window above a substrate, the semiconductor device has at least one fuse protection circuit located under the fuse window. The fuse protection circuit includes a fuse having a first end connected to a first voltage and a second end. A first transistor having a drain is connected to the second end of the fuse, a gate for receiving an input signal, and a source is connected to a second voltage. A second transistor having a drain is connected to the second end of the fuse, a gate, and a source is connected to the second voltage. A first diode having an anode and a cathode, the anode of the first diode is connected to the second voltage and the cathode of the first diode is connected to the second end of the fuse.

The present invention relates generally to semiconductor devices and more specifically to fuse circuits employed in semiconductor devices.
The design concept of making redundant cells or circuits to replace defective cells or cells to be reconfigured is of vital application in the fabrication of integrated circuits. Defective cells on a chip which arose in the fabrication process are usually identified using a chip probe. The defective cells can then be replaced with redundant cells by the redefinition of connective paths. With such a reworking process to correct fabrication defects, the number of defective cells can be greatly reduced. The use of redundant cells is employed in most memory chips and logic circuit chips to increase the yield and reduce production costs.
There are several ways of modifying the connections to substitute redundant cells for defective cells. The use of a fuse circuit is one of the most widely employed methods for swapping defective cells with redundant cells. Typically, fuse circuits are incorporated in the integrated circuit design, and the fuses of the fuse circuits are selectively blown, for example, by passing an electrical current of sufficient magnitude to cause them to open. Frequently, fuses are blown by the use of laser. In such a case, a fuse window is normally formed through insulating layers above the fuse in the area where the fuse will be blown so that the laser heating will be more effective. The laser is focused through the fuse window, the fuse absorbs the heat from the laser irradiation and the fuse melts.
Typically, logic circuits are repaired or reconfigured by blowing fuses. For example, it is common to initially fabricate a generic logic chip having a large number of interconnected logic gates. Then in a final processing step, the chip is customized to perform a desired logic function by disconnecting the unnecessary logic elements by blowing the fuses that connect them to the desired circuitry. Still other applications of laser-blown fuses are possible.
Unfortunately, conventional semiconductor devices with fuse circuits have several drawbacks. One of the problems with these fuse circuits is that they do not contribute to the ordinary operation of the device. Further, they require silicon area that could otherwise be used for circuits that perform other functions. The space under a fuse window is normally unused. This lost space is significant considering the scaling down of features sizes in the sub-micron region and the fact that at least several hundred fuse circuits are required for each device. Further still, conventional semiconductor devices with fuse circuits do not adequately discharge the charge from an ESD during laser processing.
For these reasons and other reasons that will become apparent upon reading the following detailed description, there is a need to avoid using much or all of the silicon area that is occupied by fuse circuits, which silicon area could otherwise be used for circuits that perform other functions.

Protection circuit located under fuse window


A semiconductor structure and a method for operating the same. The method includes providing a semiconductor structure. The semiconductor structure includes first, second, third, and fourth doped semiconductor regions. The second doped semiconductor region is in direct physical contact with the first and third doped semiconductor regions. The fourth doped semiconductor region is in direct physical contact with the third doped semiconductor region. The first and second doped semiconductor regions are doped with a first doping polarity. The third and fourth doped semiconductor regions are doped with a second doping polarity. The method further includes (i) electrically coupling the first and fourth doped semiconductor regions to a first node and a second node of the semiconductor structure, respectively, and (ii) electrically charging the first and second nodes to first and second electric potentials, respectively. The first electric potential is different from the second electric potential.

A conventional PN junction diode structure can be used for electrostatic discharge (ESD) protection. However, these prior art PN junction diode structures are designed for low voltage CMOS technology. Standard CMOS technology continues to scale, and cannot withstand high voltages. Power technologies integrate advanced CMOS technology (with application voltages between 1.8V and 5V), with circuitry in the 20 to 120V application range. Today, the continued scaling of CMOS technology provides a larger margin between these high voltage CMOS and low voltage CMOS. In the low voltage CMOS technology, the breakdown voltages of the CMOS junctions are less than 20V. Therefore, there is a need for a semiconductor diode structure (and a method for forming the same) which can withstand higher voltages than those of the prior art.

International Business Machines Corporation


A covert camera for surveillance in an aircraft comprises a front panel that can have an appearance other than a conventional camera. The front panel can include at least one aperture therethrough. A lens can be in or near the aperture, the lens having a field of view. A camera mount can be positioned on the front panel. The camera mount can include a sensor capable of receiving an image of at least a portion of the field of view. The camera mount can be capable of adjustment without movement of the lens.

Surveillance cameras can help detect and deter theft and unwarranted trespass to secure areas of an aircraft, including cargo areas. Preferably, such cameras operate in extreme low light or no light situations and accomplish their surveillance goals in such a manner so as to discourage tampering or attempts to disable the camera equipment.
Cameras used in aircraft can be subjected to extreme environmental conditions. Vibration, temperature fluctuations, potential shock, fluctuating lighting conditions, are just a few environmental conditions to consider. See, e.g., the international standard for environmental testing of commercial avionics as set forth in RTCA/Do-160F, Environmental Conditions and Test Procedures for Airborne Equipment. Equipment designers must account for such conditions, as well as with the added goal of minimizing equipment costs, size, power and weight for all airborne equipment and avionics. Traditional cameras have an optical element, or lens, placed a certain distance from a sensor. The image is focused by adjusting the position of the lens in relation to the sensor. The focal length, the lens type, clarity and type of image to be captured impact the design of the camera. This focusing configuration can impact the overall cost and size of a camera and limit the volume in which a camera can be placed.
In view of the above goals and requirements, there is a need for a small profile camera that can be used effectively and efficiently for covert surveillance in an aircraft environment.


The invention provides a method for producing a cell aggregate containing a ciliary marginal zone-like structure by culturing a cell aggregate containing a retinal tissue in which Chx10 positive cells are present in a proportion of 20% or more of the tissue in a serum-free medium or serum-containing medium, each containing a substance acting on the Wnt signal pathway for only a period before the appearance of a RPE65 gene expressing cell, followed by culturing the “cell aggregate in which a RPE65 gene expressing cell does not appear” thus obtained in a serum-free medium or serum-containing medium, each not containing a substance acting on the Wnt signal pathway and so on.

The ciliary marginal zone of the in vivo retina is known to perform important functions for the structural formation and maintenance of retinal tissues (see, for example, non-patent document 1) and, for example, Rdh10 gene (non-patent document 2) and Otx1 gene (non-patent document 1) are known as gene markers of the ciliary marginal zone. However, there is no known method for producing such ciliary marginal zone-like structure from pluripotent stem cells with high efficiency.

This patent is subject to a terminal disclaimer.

Method for producing ciliary marginal zone-like structure


The present invention is directed to a process for purifying and characterizing "myotrophin", a novel soluble protein factor that is believed to regulate myocardial hypertrophy in hypertension. In addition, the invention is directed to the purified and partially characterized protein factor produced by the process of the present invention, as well as uses of this factor, or its antagonist to control cardiac hypertrophy.

The present invention is directed to a process for purifying and characterizing a novel soluble protein factor, designated "myotrophin" by the inventors, that is believed to influence cardiac hypertrophy associated with hypertension. In addition, the invention is directed to the purified and partially characterized myotrophin produced by the process of the present invention, as well as the use of this factor and/or its antagonist to regulate myocardial growth.
Hypertrophy is generally defined as the increase in size of an organ or structure independent of natural growth that does not involve tumor formation. Hypertrophy of an organ or tissue is due either to an increase in the mass of the individual cells (true hypertrophy) such as in the hypertrophy of a muscle produced by physical exercise, or to an increase in the number of cells making up the tissue (hyperplasia) or to both. Certain organs, such as the heart, consist of cells which lack the ability to divide, and in such cases, hypertrophy results in an increase in the size rather than in the number of constituent cells. In other tissues such as the liver, hypertrophy of the organ is effected principally by an increase in the number of cells.
Cardiac hypertrophy relates to the enlargement of the heart due to the increased size of the myocardium, or more particularly, to the increased size of the myocyte cells which make up the myocardium layer of the heart. The myocardium is the middle layer of the walls of the heart composed of cardiac muscle. The increase in size of the heart may be due to physiological, as well as pathological, stimuli. For example, the size of the heart may be increased as a result of long periods of physical exercise or because of a valvular disorder or other types of pathological disorders.
As a result of the increased stress and/or strain placed upon the heart in condition of hypertension due to the increased total peripheral resistance, etc., cardiac hypertrophy has long been associated with hypertension.
However, the lack of a close parallelism between blood pressure levels and degree of cardiac hypertrophy has been demonstrated both in clinical studies as well as in experimental animal models (Grant, R. D., Am. Heart J. 46, pp. 154-158, 1953; Ehrstrom, M. C. Acta Med. Scand. 103, pp. 86-93, 1948; Sen, S., Tarazi, R. C., Khairallah, P. A., and Bumpus, F. M., Cir. Res. 35, pp. 775-781, 1974; and, Sen, S., Tarazi, R. C., Bumpus, F. M., Cardiovas. Res. 10, pp. 254-261, 1976). Thus, factors other than blood pressure controls appear to exist that play a role in altering myocardial structure, reducing compliance and diminishing performance and thus determining the hemodynamic state throughout course of hypertension.
Moreover, while studies performed by the inventors and others (Sen, S., Tarazi, R. C., Khairallah, P. A., and Bumpus, F. M., (abstract) Clin. ExD. Pharmacol. Physiol. 3, pp. 173-177, 1976; Sen, S., and Bumpus, F. M., Am. J. Cardiol. 44, pp. 954-958, 1979; Sen, S., Tarazi, R. C., and Bumpus, F. M., Am. J. Physiol. 240, pp. H408-H412, 1981; Sen, S., Tarazi, R. C., and Bumpus, F. M., Hypertension 2, pp. 169-176, 1980; Yamori, Y., Mori, C., Nishio, T., Ooshima, et al., Am. J. Cardiol. 44, pp. 964-969, 1969; Hollander, W., Madoff, I., Paddock, J., and Kirkpatrick, B., Circ. Res. (Suppl. 6) 38, pp. 63-72, 1976; Freis, E., Spontaneous Hypertension: Pathogenesis and Complications (Okamoto, K., ed.), pp. 231-244, Springer-Verlag, N.Y., 1972; and, Tomanek, R., Davis, J., and Anderson, S. C., Cardiovasc. Res. 13, pp. 173-182, 1979) have confirmed that cardiac hypertrophy in spontaneously hypertensive rats (SHR) can be prevented or reversed to some degree by antihypertensive treatment, such treatment is highly variable depending on the specific antihypertensive agent utilized, etc.
Of significance is the marked diversity in the ability of various antihypertensive drugs to reverse cardiac hypertrophy, even though all these drugs reduced arterial pressure to the same degree. For example, the inventors have shown (Sen, S., Tarazi, R. C., Khairallah, P. A., and Bumpus, F. M., Cir. Res. 35, pp. 775-781, 1974; and, Sen, S., Tarazi, R. C., and Bumpus, F. M., Cardiovasc. Res. 11, pp. 427-433, 1977) that alpha-methyldopa lowered pressure and reduced cardiac weight to normal levels. However, hydralazine controlled pressure, but did not reverse hypertrophy, whereas minoxidil normalized blood pressure, but actually increased heart weight (Sen, S., Tarazi, R. C ., Khairallah, P. A., and Bumpus, F. M., Cir. Res. 35, pp. 775-781, 1974; and, Sen, S., Tarazi, R. C., and Bumpus, F. M., Cardiovasc. Res. 11, pp. 427-433, 1977). These differences among various drugs could be related to: (a) varied hemodynamic effects; (b) differences in the reflexes in sympathetic stimulation; or (c) direct biochemical alteration of cardiac muscle.
In a more recent study (Sen, S., Tarazi, R. C., Am. J. Physiol. 244, pp. H97-H101, 1983), the inventors have shown that a combination of a beta blocker and a vasodilator, which led to moderate blood pressure control without increased myocardial catecholamine content, reversed myocardial hypertrophy, whereas reduction of either blood pressure alone or myocardial catecholamines alone failed to regress hypertrophy. These observations suggest involvement of the beta adrenergic system in modulation of myocardial hypertrophy. However, it is not known how the adrenergic system may modify the protein structure of the myocardium. It is possible that increased wall stress, which is induced by adrenergic stimulation, triggers increased protein synthesis; an hypothesis supported by the observation that increased stress produces fundamental alteration in the contractility of the heart (Albert, N. R., Mulleri, L. A., and Litten, R. Z., Am. J. Cardiol. 114, 947-953, 1979).
As a result, while reversal of cardiac hypertrophy with proper antihypertensive therapy has been proven, it has been shown by the present inventors and others that regression of hypertrophy is highly variable depending upon the specific hypertensive agent utilized. In addition, the biochemical aspect of such reversal is still relatively unknown. Thus, the mechanisms of the development or regression of myocardial hypertrophy cannot be fully explained by blood pressure control alone.
What is clear, however, is that the development of hypertrophy is initiated by a variety of myocardial stimuli, either mechanical or humoral. It is likely that the myocardium, in turn, produces a chemical signal that is then responsible for triggering protein synthesis and myocardial cell growth.
In a recent study, the inventors demonstrated the existence of a factor in the hypertrophied myocardium of spontaneously hypertensive rats (SHR) that stimulates protein synthesis in cultured adult rat myocytes in vitro (Sen, S., and Petscher C., Hypertension 9, pp. 261-266, 1987). In this study, the inventors described the partial purification of the stimulating factor with HPLC, first by using gel filtration and then DEAE columns. During successive purification attempts of the factor by an exchange chromatograph, the stimulating activity of the partially purified factor was only moderately increased. The molecular weight of the partially purified stimulating factor was tentatively estimated to be 8500 by a HPLC molecular sieve exclusion technique. In addition, trypsin digestion (pH 7.0-7.5) destroyed the stimulating activity. The data set forth in that study suggested that the stimulating factor is of a protein moiety, however, additional research was clearly necessary in order to purify and characterize the soluble factor and to determine its physiological importance.
The present invention is directed to the isolation and purification of this protein factor to homogeneity, and to the partially elucidation of its internal amino acid sequence. From a homology search using three different databases, the isolated, purified, and partially characterized protein factor appears to be a novel molecule with no identical homology with any known protein. The isolated, purified, and partially characterized protein factor has been named "myotrophin" by the present inventors.

Process for purifying and characterizing myotrophia, a novel peptide that regulates myocardial growth


An apparatus for building pallets comprises a jig frame adapted to maintain a plurality of deck boards in deck board locations on top of a plurality of stringers in parallel stringer locations. A gantry frame is mounted above the jig frame and a plurality of nailing guns is mounted on the gantry frame. The gantry frame is movable with respect to the jig frame to position and operate the nailing guns to nail deck boards to stringers. The nailing guns are mounted to the gantry frame such that they can move up and down with respect to the gantry frame, and the nailing guns are biased toward a lowest gun position. Each gun can move vertically so that when using uneven boards, all guns will fire.

Pallets, and especially wooden pallets are an essential component in the shipping and handling of commercial goods. The demand for pallets continues to increase each year, with the result that improvements in the apparatus and methods used in their construction are desirable. Pallets are constructed by assembling a number of wood, plastic or metal members to produce a frame structure with internal support members and top and bottom surfaces upon which freight is placed and the pallet rests. While pallets can be constructed by hand, the development of machine methods of pallet construction permits an individual operator to build pallets more rapidly and safely.
Machines and methods for use in building pallets are known in the art, as disclosed for example in U.S. Pat. No. 5,249,352 to Landers, Canadian Patent 1,193,424 to Viitanen & Billett and Canadian Patent 1,037,201 to Hayworth.
Typical pallet building machines, commonly called pallet jigs, such as disclosed in Landers, comprise a jig frame to position and align the members intended for assembly into the pallet, and a number of nailing guns mounted on a gantry frame. Typically pallet stringers are placed in the jig frame, then deck boards are placed in the jig frame on top of the stringers. The stringers and deck boards are maintained in position by elements of the jig frame. The nailing guns on the gantry frame are aligned with the stringers, and the gantry frame is mounted on rollers or the like so that the gantry frame can be moved along the jig frame parallel to the stringers. Thus each nailing gun is movable along one stringer, and can drive typically two nails through each deck board and into the stringer. Springs are provided to bias the weight of the gantry frame upwards so that the operator can readily move the gantry frame up and down to fire the nailing guns at the desired locations as the gantry frame moves along the jig frame.
Typically the nailing guns are fired by pressing the nose of the gun down on the board and then continuing to move the nailing gun downward to move the nose inward with respect to the nailing gun—when the nose has moved inward a sufficient distance the gun fires a nail into the board. Once the nose has moved inward sufficiently to fire the gun, it stops and then substantially no further inward movement of the nose with respect to the gun is possible.
The nailing guns are conventionally rigidly mounted to the gantry frame, as disclosed in Landers, so that the nose of each gun is at the same vertical location with respect to the jig frame. Then as the gantry frame is moved down, each nose contacts the deck board at the same time and, as the gantry frame is moved lower, each gun will fire at substantially the same time.
The conventional pallet jigs, as exemplified by Landers, operate satisfactorily when the deck boards and stringers have a consistent thickness. The surface of the deck board is then located at the same vertical location with respect to the jig frame under each nailing gun. When the gantry frame is moved down, the nose of each gun will contact the surface at the same time and will fire at the same time.
A problem is encountered however where the deck boards do not have a consistent thickness. Commonly pallets are used in applications where a rough deck surface would be satisfactory, and thus it would be more economical to use rough deck boards that were not planed to a consistent thickness. With such boards, the nose of one nailing gun will contact the highest portion of the rough board before the noses of the other guns contact the board surface. As the gantry frame is moved lower, the other noses will contact the board surface later. The first gun to contact the board will fire before the others, and prevent further downward movement of the gantry frame, since the nailing guns are rigidly fixed to the gantry frame. Where the thickness differential is large enough, one or more of the other nailing guns may not then fire and a nail is missed in the pallet.
Similarly where one stringer is slightly higher than another the same problem will occur. In order to satisfactorily use the prior art pallet jigs both stringers and floor boards must be consistently dimensioned, requiring the use of higher cost planed stringers and deck boards even where the end use could be satisfactorily satisfied by a pallet made of rough boards.


A dental implant system having a temporary abutment made of plastic. An impression coping, also made of plastic, is attached to the temporary abutment using a snap fit. This snap fit obviates the need to remove the temporary abutment during the process of taking an impression of the mouth in the area around an implant. The cap may be provided for the temporary abutment that is attached thereto using the same snap fit mechanism. The snap fit mechanism comprises projections formed on one of the components and recesses formed on the other of the components, where the projections engage the recesses to maintain the components in a desired position relative to each other against incidental force. However, these components may be separated by deliberate application of manual force when required.

Many systems and methods are currently available for replacing lost teeth. These systems and methods comprise the following basic steps. First, an implant is threaded into a cavity formed in the patient's jaw at the location of a lost tooth. The implant is then allowed to osseointegrate with the jaw bone. A technician will then fabricate a prosthetic tooth on a permanent abutment member. The permanent abutment member is then attached to the implant to mount the prosthetic tooth at its appropriate location. In this context, the permanent abutment member forms the structural attachment between the prosthetic tooth and the implant, and the prosthetic tooth functionally and aesthetically replaces the exposed portion of the lost tooth.
It should be clear that this basic process can be employed when replacing a plurality of teeth as well as when replacing a single tooth. In the following discussion, the present invention is described in the context of replacing a single tooth; but one of ordinary skill in the art will recognize that the principles of the present invention are equally applicable to the replacement of more than one tooth at a time.
The step of fabricating the prosthetic tooth varies with the particular patient but requires that the position of the implant be captured so that the resulting prosthesis performs as required both functionally and aesthetically. If the position of the implant is not accurately captured, the resulting prosthesis may not function properly and may not look natural when attached to the implant.
The prosthesis fabrication process comprises the steps of taking an impression of the area of the lost tooth and, with the impression, forming a model of the area of the lost tooth. The process of taking the impression comprises the steps of attaching an impression coping to the implant, injecting hardenable impression material into the area surrounding the impression coping, and, when the impression material hardens, removing the impression material with the impression coping encased therein. To fabricate the model, an analog of the implant is then attached to the impression coping encased in the impression. Hardenable model material is then placed around the implant analog and allowed to harden. The model, with the implant analog buried therein, is then removed from the impression.
The position of the implant analog in the model should, and in most systems will, reflect the position of the implant in the mouth; that is, the model will contain surfaces corresponding to the surfaces of the teeth and soft tissue, with these model surfaces being accurately located relative to the implant analog. If the model accurately reflects the position of the implant in the mouth, a technician can accurately fabricate the prosthetic tooth in a laboratory setting.
While most currently available systems for replacing lost teeth allow the fabrication of a model that accurately reflects the position of the implant in the mouth, these systems each have drawbacks that, in general, result in the process of replacing lost teeth being fairly complicated and expensive.
To the Applicant's knowledge, all of the currently available systems and methods employ metal parts down to the implant during the process of taking the impression. Such metal parts are precision machined and thus relatively expensive. Although metal parts are in theory reusable, they must be sterilized between each use. And even if sterilized, these metal parts are often difficult to clean completely. Accordingly, in practice these parts are often discarded after being used once to eliminate the possibility of cross-contamination.
The use of metal parts also increases the complexity of previously available systems or methods for replacing lost teeth. More specifically, during the process of taking an impression and subsequently creating a model from that impression, it is necessary to temporarily join two components together (i.e., the impression coping is joined to the implant and the implant analog is joined to the impression coping). Using currently available systems, whenever two metal components are temporarily joined together, one of two methods must be used: (a) one of the components must be directly threaded onto the other; or (b) one of the components is internally threaded, the other component is unthreaded, and a separate screw engages the threaded component to attach the unthreaded component to the threaded component.
In the case where both of the components are threaded, one component is usually fixed and the other is rotated relative to the fixed component. For one component to be directly threaded onto another, one of these components must be freely rotatable relative to the other. For example, in certain systems, healing abutments are provided with a threaded post extending therefrom. To attach the healing abutment to the implant, the healing abutment is rotated relative to the implant such that the threaded post formed thereon is received within the threaded cavity defined by the implant.
Rotating one component relative to the other is not possible in many situations; for example, this is not possible when one of the components is an implant fixed within the mouth and the other is an impression coping fixed within an impression.
Accordingly, with previously available systems, the various components employed are attached to each other using threaded screws during the process of taking an impression and making a model therefrom. A screw is used to securely attach the impression coping to the implant while the impression material is injected around the impression coping. And a screw is also used to attach the implant analog to the impression coping during the process of making the model from the impression.
The use of screws to attach the impression coping onto the implant increases the complexity of the process of taking the impression. The dentist must thread the screw into the implant before the impression is taken and remove the screw from the implant to remove the impression from the mouth.
Another important drawback of prior art systems and methods of replacing teeth is that these systems commonly employ 20-30 components each having a specific purpose. Many of these components work only with a specific subset of other components.
In any case, all of the components of a given system must kept in inventory. And accurate records be kept to ensure that the oral surgeon, dentist, and laboratory technician all have the right parts at the right time. Further, because these components are small and many differ only in size, the difference between one component and another incompatible component may not be obvious to the naked eye, possibly resulting in confusion among various similar looking parts.
The fact that certain components work only with certain other components reduces the flexibility of the system. For example, in certain prior art systems, the permanent abutment member must be selected prior to the process of making the impression because a particular impression coping must be used for the selected permanent abutment. If, subsequently, the dentist or laboratory technician determines that another type of permanent abutment is more appropriate, a new impression with a different impression coping must be made.


A watertight closure for a reclosable package has first and second mutually interlocking profiles. Together, the profiles have two sets of interlocking members, one on either side of a central portion. There, at least one profile has a collapsible member in its central portion. The other profile may have a compressing member or a collapsible member opposite to the collapsible member, or it may have neither. In any event, when the first and second mutually interlocking profiles are joined to one another, the collapsible member encounters and compresses against the other profile to create a watertight seal.

1. Field of the Invention
The present invention relates to the packaging art, and, more particularly, to the art of reclosable plastic bags or packages having extruded zippers. In particular, the present invention relates to extruded zippers having two sets of mutually interlocking members separated by at least one compressible or partially collapsible member, the latter forming a watertight seal when the mutually interlocking members are closed.
2. Description of the Prior Art
Reclosable bags used, for example, for storing household foodstuffs are typically made of polyethylene. As shown in U.S. Pat. No. 3,416,199 to Imamura, which is commonly assigned with the present invention, a reclosable bag may be formed of two opposed walls and having a mouth equipped with fastener profiles. These profiles include a male profile attached to one wall and a female profile attached to the other wall. The profiles are shaped so that, when they are aligned and pressed together into an engaging relationship, they form a continuous closure for the bag. The bag may be opened by pulling the walls apart at the mouth, thereby separating the male and female profiles from one another.
The prior art is replete with different shapes and arrangements for the male and female profiles. In many cases, the profiles are designed to provide relatively high resistance to opening from inside the package, while rendering the package relatively easy to open from the outside.
Because the male and female profiles must be shaped so as to be readily interlocked with one another, they may not form an entirely airtight closure. For this reason, peel seals are used in the reclosable plastic packages used for the retail sale of foodstuffs to ensure that the packages remain hermetically sealed prior to sale. Moreover, the peel seals can also serve a tamper-evident function by whitening or otherwise discoloring when being opened, thereby providing a means by which a prospective purchaser could be alerted to the possibility that the package had been opened prior to purchase.
Following purchase, there may still be a need to form a hermetic seal after the initial opening of the package to preserve the freshness of any contents remaining in the package. The present invention is a watertight closure which provides such a seal.

Watertight closure for a reclosable package


A permanent magnet shaft bearing includes a shaft bearing bushing and a flange bearing bushing which are magnetized to saturation. The outer surface of the shaft bearing bushing is magnetized to have the same polarity as the inner surface of the flange bearing bushing so that both bearing surfaces repel one another. Such repulsion creates a space between the bearing surfaces so that no physical contact is present. Both the flange bearing bushing and the shaft bearing bushing are tapered to mate each other. The shaft load requirements determine the magnetic flux density, the mass of the bearing bushings, the composition of the bearing bushings, and the proper angle of the taper. An insulating sleeve protects the bearing bushings from heat transfer in order to help retain permanent magnetization. A magnetically impermeable shield protects the bearing bushings from attracting metal particles.

1. FIELD OF THE INVENTION
The present invention relates to low friction bearing assemblies; particularly those containing magnetized components.
2. DESCRIPTION OF THE RELATED ART
Bearing assemblies are employed in many different applications where sliding or rotating movement between parts is necessary. In such bearing assemblies it is desireable to have minimal friction between the sliding or rotating parts.
Designs of conventional bearing assemblies vary depending upon the load under which they are subject. Annular ball bearings or cylindrical roller bearings are most common for axial and radial loads. Problems with these bearings are that the ball or roller bearings rotate within metal retaining rings causing friction and eventual wear. The best ball bearings are good only for some thousands of hours of use.
Noncontact bearings, where there is no metal-to-metal contact except when the bearing is at rest, are an improvement over balls or rollers, however, they are costly and impractical for most mechanical applications. Noncontact bearing members rotate on a cushion of gas or fluid except when at rest. These bearings are presently reserved for precision gyro and missile guidance systems.
Magnetization has been attempted in ball bearing applications to provide uniform spacing between the balls. Ferrolubricants, lubricants that are held in place by magnetization, have also been attempted to reduce friction and thermal problems associated with metal-to-metal contact. The problem with ferrolubricants is that they are difficult to retain at the friction points and tend to break down or change viscosity when subject to heat.
A need exists, therefore, for a bearing that reduces metal-to-metal contact between sliding or rotating bearing surfaces to reduce wear and extend bearing life. An additional need exists for such a bearing that is cost effective and efficient for most mechanical applications.