Described are non-friable, rapidly disintegrating, fast-dissolving solid dosage forms that are produced from pharmaceutically acceptable steam extruded polymers. The solid dosage forms dissolve in the mouth and are particularly useful for subjects that require or desire oral medication but have difficulty swallowing standard oral dosage forms such as tablets or in subjects suffering from emesis. The solid dosage forms are also useful for rapid drug delivery as vaginal or rectal suppositories or for oral delivery of veterinary drugs.

This invention relates to highly porous, non-friable, rapidly disintegrating, fast-dissolving solid dosage forms that are produced from pharmaceutically acceptable steam-extruded polymers. The solid dosage forms of the invention dissolve in the mouth and are particularly useful for subjects that require or desire oral medication but have difficulty swallowing standard oral dosage forms such as tablets or in subjects suffering from emesis or who require or desire a faster acting treatment, or a more palatable dosage form. The solid dosage forms of the invention are also useful as vaginal and rectal suppositories.
The present invention is a rapidly disintegrating, fast-dissolving dosage form that is broadly applicable for the pediatric, geriatric, HIV-oncology, migraine-CNS, anti-emetic, and animal health therapies. The presently described dosage forms utilize a steam extruded polymeric matrix. Rapidly disintegrating pharmaceutical dosage forms that utilize a non-steam extruded matrix have been described in U.S. Pat. No. 4,371,516 and non-steam extruded, rapidly disintegrating materials related to pharmaceutical dosage forms is described in U.S. Pat. No. 4,305,502.
Steam extruded starch compositions for use in packaging and the methods of producing such compositions have been described in U.S. Pat. Nos. 4,072,535; 4,863,655; 5,035,930; 5,043,196; 5, 286,769; 5,405,564 and 5,849,233.
This invention relates to rapidly disintegrating, fast-dissolving dosage forms for the delivery of a medicament that are produced from steam extruded pharmaceutically compatible polymers.
A second aspect of the invention is a steam extruded rapidly disintegrating, fast-dissolving dosage form produced from high amylose starch, i.e., one comprising at least about 45% by weight of amylose which is optionally derivatized and optionally comprising about 2% or more by weight of salt.
A third aspect of the invention is a steam extruded rapidly disintegrating, fast-dissolving dosage form produced from gelatin, particularly gelatin that is hydrolyzed, or other polymeric materials such as dextran, dextrin, and alginates (e.g. sodium alginate) or mixtures of polymeric materials with each other or with other carrier materials such as polyvinyl alcohol, polyvinylpyrrolidine or acacia.
A fourth aspect of the invention is a rapidly disintegrating, fast-dissolving dosage form having a uniform, closed cell structure with low density and low friability and good resilience, compressibility, disintegration and dissolution properties. The bulk density of the rapidly disintegrating, fast-dissolving dosage form will be from about 2 to about 80 mg/cc, and preferably from about 2 to about 50 mg/cc; and more preferably from about 2 to about 9 mg/cc excluding medicament and other carriers, vehicles or diluents. The bulk density of the dosage form containing drug will be from about 2 to about 550 mg/cc; and more preferably from about 2 to about 200 mg/cc.
A fifth aspect of the invention is a steam extruded rapidly disintegrating, fast-dissolving dosage form in a shaped configuration for use as a vaginal or rectal suppository.
A sixth aspect of the invention is a method of producing rapidly disintegrating, fast-dissolving dosage forms that involves mixing a medicament with the polymeric material and other optional carriers, vehicles or diluents and steam extruding the medicament-containing polymeric material into an expanded product for forming the dosage form. The medicament-containing extruded polymeric material may be formed into the final dosage form during the steam extrusion process or may undergo subsequent shaping steps such as stamping, cutting, molding or thermoforming.
A seventh aspect of the invention is a method of producing rapidly disintegrating, fast-dissolving dosage forms by steam extruding pharmaceutically acceptable polymeric materials and later loading a medicament into the extrudate. The loading of medicament can take place prior to or subsequent to the final forming or shaping steps such as stamping, cutting, molding or thermoforming.
An eighth aspect of the invention is a method of administering a medicament to a mammal in need thereof by administering a solid dosage form comprising a steam extruded pharmaceutically acceptable polymer and a medicament to the mammal.
A ninth aspect of the invention provides for kits for use by a consumer that require or desire a rapidly disintegrating, fast-dissolving dosage form. The kits comprise a solid dosage form comprising a steam-extruded polymer and a medicament and further comprise a container for holding the dosage form and instructions for the using the dosage form.
A tenth aspect of the invention is a rapidly disintegrating, fast-dissolving veterinary dosage form that is taste-masked so that consumption of the dosage form is desired by an animal thus allowing easy administration of a medicament.
An eleventh aspect of the invention is a rapidly disintegrating, fast-dissolving dosage form containing a drug compound wherein a major portion of the drug is amorphous. As used herein, the term xe2x80x9ca major portionxe2x80x9d of the drug means that at least 60% of the drug in the dispersion is in the amorphous form, rather than the crystalline form. Preferably, when amorphous drugs are used, the drug added to the rapidly disintegrating, fast-dissolving dosage form is substantially amorphous. As used herein, xe2x80x9csubstantially amorphousxe2x80x9d means that the amount of the drug in crystalline form does not exceed 25% as measured by powder X-ray diffraction analysis or by differential scanning calorimetry or by any other standard quantitative measurement. More preferably, when amorphous drugs are used, the drug added to the rapidly disintegrating, fast-dissolving dosage form is essentially amorphous. As used herein, xe2x80x9cessentially amorphousxe2x80x9d means that the amount of the drug in crystalline form does not exceed 10% as measured by the methods previously described.
The starting materials useful for the rapidly disintegrating, fast-dissolving dosage form must be pharmaceutically acceptable polymeric materials. The polymeric materials used to produce the dosage forms of the invention are highly water-soluble and form a gel phase with hot water under pressure. After extrusion the water rapidly vaporizes leaving a highly porous solid foam. This process is known as xe2x80x9csteam extrusionxe2x80x9d.
A xe2x80x9csubjectxe2x80x9d is an animal including a human that is treatable with the compositions, methods and kits of the present invention. The term xe2x80x9csubjectxe2x80x9d or xe2x80x9csubjectsxe2x80x9d is intended to refer to both the male and female gender unless one gender is specifically indicated.
xe2x80x9cSolid dosage formxe2x80x9d is defined as a rapidly-disintegrating, fast-dissolving dosage form that can be in the form of granules, pellets, sheets, tablets, capsules, shaped forms and the like.
Amorphous drugs may be used with the rapidly disintegrating, fast-dissolving dosage form to increase the rate of dissolution over crystalline forms of the drugs.
Pharmaceutically acceptable polymers disclosed herein include all manmade and natural polymers and polymeric materials that are compatible with the processes. Non-limiting examples of polymers include gelatin, particularly gelatin that is hydrolyzed, e.g. by heating in water. For example, gelatin may be partially hydrolyzed by heating a solution of the gelatin in water in an autoclave at about 120xc2x0 C. for up to 2 hours. Other polymeric materials may include dextran, dextrin, alginates (i.e., sodium alginate), hydroxypropyl methylcellulose (HPMC) or mixtures of polymeric materials with each other or with other carrier materials such as polyvinyl alcohol, polyvinylpyrrolidine or acacia. A preferred polymeric material of the invention is high amylose starch, i.e., one containing at least 45% by weight of amylose. The starch used is unlike common starch since it is resilient, not brittle. A typical starch useful for making these materials is produced by National Starch and Chemical Company (Belle Mead, N.J.) and sold under the trade name xe2x80x9cHylon VIIxe2x80x9d. This starch is composed of 70% amylose (short chainxe2x80x94no branching) and 30% amylopectin (large branched molecules). The unique low branching nature contributes to the resilient, not brittle properties and is unlike common starch, which is predominately amylopectin (large branched molecules).
It is well known that starch is composed of two fractions, the molecular arrangement of one being linear and the other being branched. The linear fraction of starch is known as amylose and the branched fraction amylopectin. Starches from different sources, e.g., potato, corn, tapioca, rice, etc., are characterized by different relative proportions of the amylose and amylopectin components. Some plant species have been genetically developed and are characterized by a large preponderance of one fraction over the other. For instance, certain varieties of corn which normally contain about 22-28% amylose have been developed which yield starch composed of over 45% amylose. These hybrid varieties have been referred to as high amylose or amylomaize.
High amylose corn hybrids were developed in order to naturally provide starches of high amylose content and have been available commercially since about 1963. Suitable high amylose starches useful herein are any starches with an amylose content of at least about 45% and preferably at least about 65% by weight. While high amylose corn starch has been especially suitable, other starches which are useful include those derived from any plant species which produces or can be made to produce a high amylose content starch, e.g., corn, peas, barley and rice. Additionally, high amylose starch can be obtained by separation or isolation such as the fractionation of a native starch material or by blending isolated amylose with a native starch.
The high amylose starch used in this invention may be unmodified or modified and the term starch as used herein includes both types. By modified it is meant that the starch can be derivatized or modified by typical processes known in the art, e.g., esterification, etherification, oxidation, acid hydrolysis, cross-linking and enzyme conversion. Typically, modified starches include esters, such as the acetate and the half-esters of dicarboxylic acids, particularly the alkenylsuccinic acids; ethers, such as the hydroxyethyl- and hydroxypropyl starches and starches reacted with hydrophobic cationic epoxides; starches oxidized with hypochlorite; starches reacted with cross-linking agents such as phosphorus oxychloride, epichlorohydrin, and phosphate derivatives prepared by reaction with sodium or potassium orthophosphate or tripolyphosphate and combinations thereof. These and other conventional modifications of starch are described in publications such as Starch: Chemistry and Technology, Second Edition, edited by Roy L. Whistler et al. Chapter X; Starch Derivatives: Production and Uses by M. W. Rutenberg et al., Academic Press, Inc., 1984.
One modification of the high amylose starches used in this invention that is especially advantageous, is the etherification with alkylene oxides, particularly those containing 2 to 6, preferably 2 to 4, carbon atoms. Ethylene oxide, propylene oxide and butylene oxide are exemplary compounds useful in etherifying the starting starch materials with propylene oxide being especially preferred. Varying amounts of such compounds may be used depending on the desired properties and economics. Generally, up to 15% or more and preferably, up to about 10%, by weight, based on the weight of starch will be used. Extruded starches modified in this manner, show improved expansion, uniformity and resiliency.
Pharmaceutically acceptable additive compounds may also be combined or blended with the polymeric starting materials to improve properties such as strength, flexibility, resiliency, color, etc. Compounds such as polyvinyl alcohol, monoglyceride, and polyethylene vinyl acetate are typical additives which may be used. They are used in any amount provided the extrusion of the starch and the properties of the expanded product are suitable. Typically, up to about 50% by weight of such additives, and preferably up to about 10% by weight, may be used. Additive polymer compounds may be included for forming or stabilizing solid dispersions of amorphous drug compounds. A preferred class of polymers comprises ionizable and nonionizable cellulosic polymers (including those with ether or ester or a mixture of ester/ether substituents and copolymers thereof, including both so-called xe2x80x9centericxe2x80x9d and xe2x80x9cnon-entericxe2x80x9d polymers); and vinyl polymers and copolymers having substituents of hydroxyl, alkylacyloxy and cyclicamido.
Exemplary ionic cellulosics include carboxymethylcellulose (CMC) and its sodium salt, carboxyethylcellulose (CEC), hydroxyethylmethylcellulose acetate phthalate, hydroxyethylmethylcellulose acetate succinate, hydroxypropylmethylcellulose phthalate (HPMCP), hydroxypropylmethylcellulose succinate, hydroxypropylcellulose acetate phthalate (HPCAP), hydroxypropylcellulose acetate succinate (HPCAS), hydroxypropylmethylcellulose acetate phthalate (HPMCAP), hydroxypropylmethylcellulose acetate succinate (HPMCAS), hydroxypropylmethylcellulose acetate trimellitate (HPMCAT), hydroxypropylmethylcellulose acetate phthalate (HPMCAP), hydroxypropylcellulose butyrate phthalate, carboxymethylethylcellulose and its sodium salt, cellulose acetate phthalate (CAP), methylcellulose acetate phthalate, cellulose acetate trimellitate (CAT), cellulose acetate terephthalate, cellulose acetate isophthalate, cellulose propionate phthalate, cellulose propionate trimellitate, cellulose butyrate trimellitate and mixtures thereof.
Exemplary nonionic cellulosics include methylcellulose (MC), ethyl cellulose (EC), hydroxyethyl cellulose (HEC), hydroxypropylcellulose (HPC), hydroxypropylmethylcellulose (HPMC), hydroxypropylmethylcellulose acetate, hydroxyethylmethylcellulose, hydroxyethylcellulose acetate, hydroxyethylethylcellulose and mixtures thereof.
Exemplary vinyl polymers and copolymers useful as dispersion polymers include methacrylic acid copolymers, aminoalkyl methacrylate copolymers, carboxylic acid functionalized polymethacrylates, and amine-functionalized polymethacrylates, poly (vinyl acetal) diethylaminoacetate, polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), polyvinyl alcohol/polyvinyl acetate (PVA/PVAc) copolymers and mixtures thereof.
Other useful dispersion polymers include polyethylene glycol/polypropylene glycol (PEG/PPG) copolymers, polyethylene/polyvinyl alcohol (PE/PVA) copolymers, dextrin, pullulan, acacia, tragacanth, sodium alginate, propylene glycol alginate, agar powder, gelatin, starch, processed starch, glucomannan, chitosan and mixtures thereof.
Particularly preferred dispersion polymers are PVA, PVP, PVA/PVAc copolymers and cellulosic polymers that are aqueous-soluble over at least a portion of the pH range 1 less than pH less than 8, including HPMC, HPMCP, HPMCAS, CAP, CAT and mixtures thereof.
In addition to the above noted polymeric materials, modified starches and additive compounds, a pregelatinized form of the starch starting material may be used, if desired.
When using modified starch compounds, it is advantageous that the modified starch starting material contains about 2% or more by weight of salt as well as the required high amylose content. The salt in the modified starch can either be added to the already prepared starch starting material or it can be residual salt, as determined by ash content, that remains after the preparation of the modified starch, e.g., in the well known method of producing hydroxyalkyl starch ethers using alkaline conditions where salts such as sodium sulfate and sodium chloride are used. The amount of residual salt in the starch can be controlled by the amount of washing after the modified polymeric product is produced. Inclusion of such salt results in a more uniform closed cell structure. The salt used can be any inorganic, water soluble salt or mixtures thereof and more particularly, an alkali metal or alkaline earth metal salt with the sodium salts such as sodium sulfate and sodium chloride being preferred. The amount of salt used will be about 2% or more and preferably about 3% or more by weight based on the weight of the starch. The particularly useful modified starch materials for this embodiment are the etherified materials such as the hydroxyalkyl starches produced by the etherification with alkylene oxides and the esterified materials such as those acetylated with acetic anhydride, with the etherified materials being preferred.
In preparing the solid dosage forms of the invention, an extrusion process, either alone or in combination with other forming operations, may be used depending on the type of final product desired. A pharmaceutically acceptable polymeric starting material is used as feedstock for an extruder. The expanded polymeric product leaving the extruder is typically in a rope or cylindrical form. By varying the size and configuration of the die opening of the extruder, different forms such as sheets of varying thickness and widths, irregular profiles and other shapes may be obtained.
When dosage forms of different shapes and design are desired, other forming operations subsequent to the extrusion operation may be utilized. One such readily adaptable technique involves thermoforming. In this operation, a material is heated to a temperature at which it is pliable or shapable and then forced against a mold by applying vacuum, air or mechanical pressure. After the expanded polymeric product leaves the extruder, it is still quite hot and malleable and therefore well suited for the thermoforming step. Shaped dosage forms such as tablets can be formed by thermoforming an extruded starch sheet. Additionally, dosage forms of increased density and thickness can be obtained by pressing together layers of one or more extruded polymeric sheets.
Other methods of forming the expanded polymeric products may also be used in addition to or in substitution for the extrusion/thermoforming operations discussed above. Such methods include injection molding, blow molding, extrusion-blow molding and stamping, as well as combinations of these and other methods.
One method used in preparing the solid dosage forms of this invention is an extrusion process wherein the starting polymeric material such as high amylose starch is fed into an extruder and conveyed through the apparatus under select conditions. The product emerging from the extruder is an expanded, closed cell, low density material with good resilience, compression, dissolution and disintegration properties and low friability making it particularly suitable for oral dosing where swallowing of a conventional solid dosage form by a subject is difficult or undesirable.
The important property characteristics of the steam extruded solid dosage form of this invention are its relatively low density, as well as its resilience and compressibility. The uniform, closed cell structure of the product with its characteristic tiny bubble formation results in a resilient, non-friable dosage form that is easily loaded with medicament and is rapidly disintegrating and fast dissolving upon administration. The fast-dissolving dosage form gives a pleasant mouth feel in that it quickly dissolves with slight effervescence into a pleasant-tasting syrup. A closed cell structure is defined as one having largely nonconnecting cells, as opposed to open cells which are largely interconnecting or defined as two or more cells interconnected by broken, punctured or missing cell walls. The tiny bubble formation generally results in a small cell size of typically about 100 to about 600 microns.
In order to obtain the expanded, closed cell structure characteristic of the desired dosage form, it is important that the total moisture content of the pharmaceutically acceptable polymeric material feed be at a level of about 25% or less by weight, based on the dry weight of polymeric material. By total moisture or water content is meant both the residual moisture of the material, that is the amount picked up while stored at ambient conditions, and the amount of water fed to the extruder. Typically, a polymeric material such as starch, and particularly high amylose starch, will contain about 9 to about 12% residual moisture. Enough water must be present to allow the material to be processed, mixed and heated to the desired temperatures. While some water may be added to the extruder, only an amount which will bring the total moisture level to about 25% or less can be added. This is believed to be necessary to allow for the desired expansion and cell structure formation in the prepared product. Accordingly, while the total moisture content that is used for carrying out the process may vary somewhat, depending on the actual material used and other process variations, a range of from about 10 to about 25%, preferably from about 13 to about 19% and more preferably from about 14 to about 17% by weight, will generally be suitable. The temperature of the material in the extruder will be increased to reach about 150xc2x0 C. to about 250xc2x0 C. This temperature must be maintained in at least the section of the extruder closest to the die and just before the material leaves the extruder. The die is positioned at the point or location at the end of the extruder from which the extruded material emerges or exits the apparatus into the ambient air. Depending on the particular material being processed, as well as other process variations, this temperature can vary somewhat within the noted range and preferably will be from about 160xc2x0 C. to about 210xc2x0 C. When modified starch such as the etherified material is used, the temperature used will preferably be from about 160xc2x0 C. to about 180xc2x0 C. while the use of unmodified starch will have a preferred temperature of from about 170xc2x0 C. to about 210xc2x0 C. in at least the section of the extruder closest to the die. By maintaining these conditions in the extruder, the material upon leaving the die and extruder outlet into the open air, expands and cools to form an expanded, low density product.
The apparatus used in carrying out this process may be any screw-type extruder. While the use of a single- or twin-screw extruder may be used, it is preferred to use a twin-screw extruder. Such extruders will typically have rotating screws in a horizontal cylindrical barrel with an entry port mounted over one end and a shaping die mounted at the discharge end. When twin screws are used, they may be corotating and intermeshing or nonintermeshing. Each screw will comprise a helical flight or threaded section and typically will have a relatively deep feed section followed by a tapered transition section and a comparatively shallow constant-depth meter section. The screws, which are motor driven, generally fit snuggly into the cylinder or barrel to allow mixing, heating and shearing of the material as it passes through the extruder.
Control of the temperature along the length of the extruder barrel is important and is controlled in zones along the length of the screw. Heat exchange means, typically a passage, such as a channel, chamber or bore located in the barrel wall, for circulating a heated media such as oil, or an electrical heater such as calrod or coil type heaters, is often used. Additionally, heat exchange means may also be placed in or along the shaft of the screw device.
Variations in any of the elements used in the extruder may be made as desired in accordance with conventional design practices in the field. A further description of extrusion and typical design variations can be found in Encyclopedia of Polymer Science and Engineering, Vol. 6, 1986, pp. 571 to 631. The expanded polymer product may be formed in different shapes by varying the size and configuration of the die opening. The product thus may be obtained in forms such as sheets, tablets, granules or forms intended for vaginal or rectal suppositories thereby extending the type of configuration in which it might be used.
Thermoforming as well as other forming operations which may be used in making the shaped product of this invention are well known in the art. In carrying out a thermoforming operation, typically the equipment would include a heater (if necessary) or means to maintain/control/adjust the temperature of the sheet or article being worked on, a mold, pressure producing means, i.e., air, vacuum or mechanical as well as auxiliary means to hold and transfer the article, and optional means such as cutting, trimming, etc. A description of illustrative thermoforming operations and equipment used therein may be found in Encyclopedia of Polymer Science and Engineering, Vol. 13, 1976, pp. 832 to 843. This and other well known forming operations which may be used are further described in the Encyclopedia of Chemical Technology, Vol. 18, 1982, pp. 184 to 206.
The medicament contained in the fast-dissolving dosage form of the invention may be added to the polymeric material prior to extrusion. When the medicament is added to the polymeric material prior to extrusion, the medicament is homogeneously blended with the polymeric material (feed material) and the mixture subjected to extrusion as described above. The medicament may be in amorphous form and may be stabilized with other additives or may also be in the form of an amorphous dispersion. The dosage forms of the present invention may incorporate ingredients in addition to the medicament that may also be blended with the polymeric material prior to extrusion. For example the solid dosage form of the present invention may incorporate pharmaceutically acceptable adjuvants. Such adjuvants include, for example, coloring agents, flavoring agents, preservatives (i.e., bacteriostatic agents), and the like. The medicament may be microencapsulated or coated and certain unit operations may be performed on the medicament to control the particle size which is added to the fast-dissolving dosage form. The fast-dissolving dosage form may also be taste masked for the oral delivery of bitter medicaments. In the case of veterinary drugs, the fast-dissolving dosage form may be formulated to possess a desirable taste so that dosing of the animal with medicament may be readily performed.
The solid dosage forms of the present invention may also be produced by first extruding the polymeric material and cutting or molding the extruded material to the desired size and shape and then subsequently adding or xe2x80x9cloadingxe2x80x9d the medicament to the dosage form. The loading of the medicament to the dosage form can be performed by first dissolving the medicament in a solvent, preferably a nonaqueous solvent, and then applying the solvent containing dissolved medicament to the dosage form. The solvent containing dissolved medicament is absorbed into the dosage form or deposited into the dosage form and then evaporated, leaving the medicament in the dosage form. The deposited or loaded medicament may be in amorphous form and may be stabilized with other additives or may also be in the form of an amorphous dispersion. Other pharmaceutically acceptable adjuvants can be similarly applied to the extruded dosage form in solution either prior to or subsequent to the loading of medicament. Alternatively, adjuvants can be added to the polymeric material prior to extrusion and thereby are contained in the extruded, shaped dosage form prior to the loading of medicament. Non-limiting examples of suitable solvents include methanol, ethanol, acetone and ethylacetate as well as mixtures thereof.
The pharmaceutical solid dosage forms of the invention may be employed to administer a wide variety of pharmaceutical substances. In this specification the term xe2x80x9cpharmaceutical substancesxe2x80x9d not only includes medicaments for administration to human and non-human animals but also contraceptives (particularly oral contraceptives). Typical drugs which can be administered by means of this invention include, for example, drugs for treating coronary disorders, e.g., digoxin, dofetilide; antihistamines e.g., cetirizine; oral vaccines; enzymes; anti-anginal drugs, e.g., glyceryl trinitrate; peripheral vasodilators and anti-hypertensives e.g., indoramin amlodipine, nifedipine; vasoconstrictors, e.g., ergotamine; analgesics e.g., meptazinol, pentazocine; hypnotics; major and minor tranquillizers e.g., lorazepam, oxazepam, temazepam; anti-depressants e.g., ciclazindol, sertraline; anti-convulsants e.g., clonazepam; antibiotics e.g., azithromycin, trovafloxacin, sulbactam; antifungals e.g., fluconazole, voriconazole; CNS stimulants e.g., pemoline; drugs for the treatment of Alzheimer""s disease e.g., donepezil; drugs for the treatment of urinary incontinence e.g., darifenacin; drugs for the treatment of osteoporosis e.g., droloxifene; muscle relaxants e.g., orphenadrine; aldose reductase inhibitors e.g., zopolrestat, neuromuscular drugs e.g., pyridostigmine; gonadal hormones and oral contraceptives e.g., ethynyl estradiol, norgestrel; corticosteroids e.g., prednisolone; local anaesthetics; antipsychotics e.g., ziprasidone; HGM-CoA reductase inhibitors e.g., atorvasatin; anti-inflammatories e.g., oxaprozin, celecoxib, valdecoxib; drugs acting on the uterus e.g., hyoscine butyl bromide; anti-allergics e.g., triprolidine and drugs relieving poisoning; metabolic dysfunction e.g., methysergide and drugs for the treatment of male erectile dysfunction, e.g., sildenifil; drugs for the treatment of diabetes e.g., glipizide; drugs for the treatment of migraine headache e.g., eletriptan, sumatriptan; adrenergic antagonists e.g., doxazosin. The pharmaceutical dosage form is particularly useful for oral administration of drugs. This form of administration can be used for administration of drugs which are normally absorbed via the gastrointestinal tract but is also useful for administration of drugs (e.g. nitroglycerin) via the buccal route since such drugs may be very rapidly absorbed by the use of the present invention.
All references cited herein are incorporated by reference. In the case of a conflict between the cited references and the present text, the present text will be controlling.
In the following examples which are merely illustrative of the various embodiments of this invention, all parts and percentages are given by weight and all temperatures are in degrees Celsius unless otherwise noted.
The following procedures were used to determine the characteristic properties of material being evaluated and as specified throughout the description and claims:
Bulk Density
Bulk density can be measured by different methods. One method is by simple measurement of the dimensions of a steam extruded polymeric product and calculation of the measured product""s volume. The sample steam extruded polymeric product is then weighed and the weight of the product is divided by the calculated volume to determine density. Alternatively, and perhaps more precisely, bulk density is measured by the volume replacement method described by M. Hwang and K. Hayakawa in xe2x80x9cBulk Densities of Cookies Undergoing Commercial Baking Processesxe2x80x9d, Journal of Food Science, Vol. 45, 1980, pp. 1400-1407. Essentially, this involves taking a beaker of known volume, i.e., 500 ml. and determining the weight of small glass beads (diameter 0.15-0.16 mm) needed to fill the beaker thus establishing the density of the glass beads to be established (Eqn. II (below)). The weight of a sample is measured and by measuring the weight of glass beads that were needed to replace the volume of that sample, the density of the sample was calculated using the following equations:                               d          s                =                                            W              s                                      W                              g                                                  xe2x80x83                                                r                                              xc3x97                      d            g                                              (Eqn.  I)                                          d          g                =                              W            gb                                V            b                                              (Eqn.  II)
where
ds=density of sample
Ws=weight of sample
Wgr=weight of glass beads needed to replace volume of sample
dg=density of glass beads
Wgb=weight of glass beads needed to fill beaker
Vb=volume of beaker
Resiliency
Resiliency (also called rebound resilience or relaxation) refers to the ability of a material to recover to its original shape after it has been deformed by a force. Resiliency can be determined using a texture analyzer such as a Stevens LFRA Texture Analyzer employing a cylindrical probe (TA-6, 0.25xe2x80x3 diameter) run at a probe speed of 0.5 mm/sec and a probe distance of 0.1 mm.
Sample extrudates are cut into 1-inch long pieces, placed on the texture analyzer""s sample table, and secured with pins. The probe is lowered automatically using the above conditions. After the probe is fully lowered, it is held at that distance for one minute before being released. The force required to initially compress the sample and the force required to compress the sample after one minute is determined. The percent recovery of the sample is determined by dividing the compression force after one minute by the initial compression force and multiplying by 100. A higher percent recovery corresponds to a material having a better resiliency.
Compressibility
The compressibility, i.e., the force necessary to deform a material of a sample is determined using a texture analyzer employing the conditions as noted above in measuring resiliency.
Sample extrudates cut into 1-inch long pieces are placed on the analyzer""s sample table and secured with pins. The probe is lowered and raised automatically with the force required to compress the sample being measured in g/cm2. This analysis is repeated two additional times using a fresh piece of sample extrudate each time. The average of three measurements is taken as the compressibility value. A high value is attributed to a sample that is relatively hard, i.e., less compressible, while a lower value is attributed to a sample that is easily compressible.
Dosage Form Friability
Dosage form friability is measured by the United States Pharmacopeia/National Formulary (USP/NF) method 1261 (United States Pharmacopeia, Rockville, Md., USA) and is summarized below. Measurement of tablet friability supplements other physical strength measurements, such as tablet crushing strength.
For friability measurements, a drum is used with an internal diameter between 283 and 291 mm and a depth between 36 and 40 mm. The drum is of transparent synthetic polymer with polished internal surfaces, and not subject to static build-up. (An apparatus meeting these specifications is available from laboratory supply houses such as VanKel Industries, Inc., 36 Meridian Road, Edison, N.J. 08820, or from Erweka Instruments, Inc., 56 Quirk Road, Milford, Conn. 06460.). One side of the drum is removable. The tablets are tumbled at each turn of the drum by a curved projection with an inside radius between 75.5 and 85.5 mm that extends from the middle of the drum to the outer wall. The drum is attached to the horizontal axis of a device that rotates at 25(xc2x1)1 rpm. Thus, at each turn the tablets roll or slide and fall onto the drum wall or onto each other.
For tablets with a unit mass equal to or less than 650 mg, a sample of whole tablets corresponding to 6.5 g is taken. For tablets with a unit mass of more than 650 mg, a sample of ten whole tablets is taken. The tablets are carefully dedusted prior to testing. The tablet sample is accurately weighed and placed in the drum. The drum is rotated 100 times, and the tablets removed. Any loose dust is removed from the tablets and the tablets are accurately weighed.
Generally, the test is run once. If obviously cracked, cleaved, or broken tablets are present in the tablet sample after tumbling, the sample fails the test. If the results are doubtful or if the weight loss is greater than the targeted value, the test should be repeated twice and the mean of the three tests determined. A maximum weight loss of not more than 1% of the weight of the tablets being tested is considered acceptable for most products. In the case of new formulations, an initial weight loss of 0.8% would be permitted until sufficient packaging data are obtained to extend the limit to a targeted value of 1%.
If tablet size or shape causes irregular tumbling, the drum base is adjusted so that the base forms an angle of about 10 degrees with the bench top and the tablets no longer bind together when lying next to each other, which prevents them from falling freely.
Dosage Form Disintegration
Dosage form disintegration is measured by the United States Pharmacopeia/National Formulary (USP/NF) method 701 (United States Pharmacopeia, Rockville, Md., USA) and is summarized below:
For the purposes of this test, disintegration does not imply complete solution of the unit or even of its active constituent. Complete disintegration is defined as that state in which any residue of the unit, except fragments of insoluble coating or capsule shell, remaining on the screen of the test apparatus is a soft mass having no palpably firm core.
Apparatus
The apparatus consists of a basket-rack assembly, a 1000-mL, low-form beaker, 142 to 148 mm in height and having an outside diameter of 103 to 108 mm for the immersion fluid, a thermostatic arrangement for heating the fluid between 35xc2x0 C. and 39xc2x0 C., and a device for raising and lowering the basket in the immersion fluid at a constant frequency rate between 29 and 32 cycles per minute through a distance of not less than 5.3 cm and not more than 5.7 cm. The volume of the fluid in the vessel is such that at the highest point of the upward stroke the wire mesh remains at least 2.5 cm below the surface of the fluid and descends to not less than 2.5 cm from the bottom of the vessel on the downward stroke. The time required for the upward stroke is equal to the time required for the downward stroke, and the change in stroke direction is a smooth transition, rather than an abrupt reversal of motion. The basket-rack assembly moves vertically along its axis. There is no appreciable horizontal motion or movement of the axis from the vertical.
Basket-Rack Assembly
The basket-rack assembly consists of six open-ended transparent tubes, each 7.75xc2x10.25 cm long and having an inside diameter of 20.7 to 23 mm and a wall 1.0 to 2.8 mm thick; the tubes are held in a vertical position by two plastic plates, each 8.8 to 9.2 cm in diameter and 5 to 7 mm in thickness, with six holes, each 22 to 26 mm in diameter, equidistant from the center of the plate and equally spaced from one another. Attached to the under surface of the lower plate is a woven stainless steel wire cloth, which has a plain square weave with 1.8- to 2.2-mm mesh apertures and with a wire diameter of 0.60 to 0.655 mm. The parts of the apparatus are assembled and rigidly held by means of three bolts passing through the two plastic plates. A suitable means is provided to suspend the basket-rack assembly from the raising and lowering device using a point on its axis.
The design of the basket-rack assembly may be varied somewhat provided the specifications for the glass tubes and the screen mesh size are maintained.
Procedure
One dosage form is placed in each of the six tubes of the basket and the apparatus is operated using deionized water maintained at 37xc2x12xc2x0 C. as the immersion fluid. The duration of operation of the apparatus required for the solid dosage form to form a soft mass is recorded.
Dosage Form Dissolution
Dosage form dissolution is measured by the United States Pharmacopeia/National Formulary (USP/NF) method 711 (United States Pharmacopeia, Rockville, Md., USA) and is summarized below:
Apparatus 1
The assembly consists of the following: a covered vessel made of glass or other inert, transparent material; a motor; a metallic drive shaft; and a cylindrical basket. The vessel is partially immersed in a suitable water bath of any convenient size or placed in a heating jacket. The water bath or heating jacket permits holding the temperature inside the vessel at 37xc2x10.5xc2x0 C. during the test and keeping the bath fluid in constant, smooth motion. No part of the assembly, including the environment in which the assembly is placed, contributes significant motion, agitation, or vibration beyond that due to the smoothly rotating stirring element. An apparatus that permits observation of the specimen and stirring element during the test is preferable. The vessel is cylindrical, with a hemispherical bottom and with one of the following dimensions and capacities: for a nominal capacity of 1 liter, the height is 160 mm to 210 mm and its inside diameter is 98 mm to 106 mm; for a nominal capacity of 2 liters, the height is 280 mm to 300 mm and its inside diameter is 98 mm to 106 mm; and for a nominal capacity of 4 liters, the height is 280 mm to 300 mm and its inside diameter is 145 mm to 155 mm. Its sides are flanged at the top. A fitted cover may be used to retard evaporation. The shaft is positioned so that its axis is not more than 2 mm at any point from the vertical axis of the vessel and rotates smoothly and without significant wobble. A speed-regulating device is used that allows the shaft rotation speed to be selected and maintained at the rate specified in the individual monograph, within xc2x14%.
The shaft and basket components of the stirring element are fabricated of stainless steel, type 316 or equivalent, to the specifications described in USP/NF method 711. A basket having a gold coating 0.0001 inch (2.5 xcexcm) thick may be used. The dosage unit is placed in a dry basket at the beginning of each test. The distance between the inside bottom of the vessel and the basket is maintained at 25xc2x12 mm during the test.
Apparatus 2
The assembly from Apparatus 1 is used except that a paddle formed from a blade and a shaft is used as the stirring element. The shaft is positioned so that its axis is not more than 2 mm at any point from the vertical axis of the vessel and rotates smoothly without significant wobble. The vertical center line of the blade passes through the axis of the shaft so that the bottom of the blade is flush with the bottom of the shaft. The distance of 25xc2x12 mm between the blade and the inside bottom of the vessel is maintained during the test. The metallic or suitably inert, rigid blade and shaft comprise a single entity that may be coated with a suitable inert coating. The dosage unit is allowed to sink to the bottom of the vessel before rotation of the blade is started. A small, loose piece of nonreactive material such as not more than a few turns of wire helix may be attached to dosage units that would otherwise float. Other validated sinker devices may be used.
Dissolution Medium
Deionized water is used as the dissolution medium.
Procedure
The stated volume of the dissolution medium (xc2x11%) is placed in the vessel of the apparatus. The dissolution medium is equilibrated to 37xc2x10.5xc2x0C., and the thermometer removed. One solid dosage form is placed in the apparatus, taking care to exclude air bubbles from the surface of the dosage-form unit and either apparatus is immediately operated at a rate of 50 rpm. The concentration of dissolved drug in dissolution medium is measured over time by ultraviolet spectrophotometer to calculate the dissolution rate.

Rapidly disintegrating and fast-dissolving solid dosage form


A method and system for measuring heat energy of a combustible fluid in which light having wavelengths in the near-infrared is directed into a test cell containing the combustible fluid and portions of the light not absorbed by the combustible fluid and passing out of the cell are spatially dispersed by wavelength, forming a light spectrum that is projected onto a detector. The light spectrum is digitized and inputted into a data processing unit in which it is compared to the actual spectrum of the light source stored in the system to determine the absorbance spectrum of the combustible fluid. The system is spectrally calibrated by identifying known spectral features of the combustible gas absorbance spectrum. To correct for deviations in the original light source spectrum, a light source calibration system is employed. Upon determination of the absorbance spectrum of the combustible fluid, the heating value of the combustible fluid is determined by comparing the absorbance spectrum to a plurality of spectra located within an on-board database.

1. Field of the Invention
This invention relates to a method and apparatus for the measurement of a physical property of a fluid that is dependent upon a physical characteristic of at least one functional group and is related to the quantity of that functional group in the fluid. More particularly, this invention relates to the measurement of the heating value of a fuel gas at-line and in real time. Even more particularly, this invention relates to a method and apparatus for measuring the heating value of a combustible gaseous fuel mixture, including functional groups and molecules, using near infrared absorption spectroscopy.
2. Description of Related Art
Historically, the heat energy content of a combustible fluid was determined by burning precisely defined amounts of the fluid, e.g. natural gas, to determine the amount of energy produced from the combustion. Other methods determined the concentration of each whole combustible compound in the mixture, defining the energy content for each whole combustible compound, and summing them to yield the heat energy content of the entire mixture.
The heat energy content of natural gas flowing through a pipeline, which natural gas typically contains methane, ethane, propane and higher alkane hydrocarbons, frequently fluctuates, even over relatively short periods of time. Conventional methods of measurement generally require bypass flow-lines or fluid extraction to provide gas samples which are then taken to a lab and burned. The temperature of the flame is then measured. It is difficult to both continuously and accurately measure the energy content of natural gas in pipelines, and the lack of any convenient means for making such continuous and accurate measurements may result in improper charges during the course of a day to the disadvantage of both buyers and sellers.
Commercially, there are no known products capable of accurately determining the heating value of a fuel gas without removing a gas sample and reducing the sample pressure for analysis. Available sensors are primarily comprised of calorimeters and gas chromatographs (GCs). However, such devices, in addition to requiring the removal of samples from pipelines, have slow response times, and have high initial and maintenance costs.
One technique for addressing the need for both continuous and accurate measurement of the heat energy content of combustible gaseous fluid mixtures employs infrared spectroscopy in which infrared radiation causes groups of atoms of organic compounds to vibrate about their covalent bonds. Because of the vibrations, the groups of atoms absorb a quantified amount of infrared energy in particular regions of the spectrum. U.S. Pat. No. 4,594,510 to Brown et al. teaches a heat energy measuring system which directs radiation through a sample of a combustible fluid and detects the absorbance of at least one combustible component of the combustible fluid at a selected spectral line, where there is at least one spectral line for each combustible component to be examined in the fluid. The system also combines at least one heat energy proportionality factor with the absorbance at each spectral line and sums these combinations to determine the heat energy of the fluid. Calibration for specific hydrocarbon species is achieved with an on-board system of individual cells of gases from which calibration matrices are calculated. This method of calibration disadvantageously adds a significant amount of time and complexity to the system.
U.S. Pat. No. 5,822,058 to Adler-Golden et al. teaches the use of absorption spectroscopy to derive the heat of combustion of a combustible mixture. The absorption spectrum is measured by utilizing a light source, light dispersing device, and a detector. However, the heat of combustion is not measured directly. Rather, the mixture composition is first determined from which the heat of combustion is derived by relating individual hydrocarbon heats of combustion. The '058 patent further teaches the use of absorption spectra of natural gas over the wavelength range of about 700-1000 nm. The detector is a silicon detector which cannot be used to detect wavelengths higher than about 1000 nm. Light source degradation is addressed by allowing a second fiber-optic cable from the light source to be directed straight to the spectrometer and then to the detector. This is able to be accomplished because a 2D detector is used. This larger detector has more surface area, thereby allowing for a second spectrum to be analyzed.
U.S. Pat. No. 6,555,820 B1 to Tacke et al. teaches a photometric device and method for determining the gross calorific value of natural gas having a radiation source that produces a measuring beam and a modulation unit to modulate a measuring beam. A test cell with a test gas and a receiver for the beam are arranged successively in the path of the measuring beam. The measuring signals of the receiver are supplied to an evaluation unit that includes at least one signal amplifier for amplification of the signals. The gross calorific value of the gas is indicated by the sum of the amplified measuring signals produced in a computing machine. However, no means are provided for tracking the fluctuations or degradation of the light source spectrum, which fluctuations or degradation may constitute a large source of error when calculating gas energy content.

Method and apparatus for optically measuring the heating value of a multi-component fuel gas using nir absorption spectroscopy


In one embodiment, a networking device receives packets of a traffic flow destined for a mobile system. The networking device sends a first flowlet of the traffic flow towards the mobile system via a first wireless access point. The networking device determines an idle time between the first flowlet and a second flowlet of the traffic flow. The networking device sends, based on the idle time, the second flowlet towards the mobile system via a second wireless access point.

Cellular network coverage has made Internet connectivity increasingly ubiquitous. This has led to an ever-increasing demand for bandwidth, to accommodate traffic such as multimedia content and communications (e.g., bandwidth-intensive high definition video streaming or real time video calls, etc.). For instance, passengers of public transportation now expect on-board, high-speed connectivity, which implies a reliable wireless ground-to-vehicle communication.
In general, mobile wireless backhauling is challenging, particularly in cases of fast-moving mobile systems, such as trains, busses, mine carts, trucks, cranes, and the like. These vehicles have to provide connectivity to onboard wired and/or wireless devices without any interruptions. Cellular technologies, such as Long-Term Evolution (LTE), are typically not practical for such scenarios, so backhauling is performed by Wi-Fi between mobile nodes (e.g., on a train) and distributed nodes along the path (e.g., trackside nodes along the rails). However, the dynamic nature of the network, as well as the environmental radio frequency (RF) conditions, may lead to packet losses, reduced throughput, and other such conditions.
Make-before-break roaming can help to allow a mobile node to smoothly transition from one access point to another without a loss of connectivity, by ensuring that a new connection between the mobile node and a new access point is established before breaking its older connection. While this approach can help to avoid interruptions in the communications for the mobile node, this approach can also lead to packets sent to the mobile node becoming misordered. Even if the mobile node is able to correct the ordering of the packets, this extra operation can impinge on any deterministic or low latency requirements of the traffic.

Reducing packet misorderings in wireless networks


An optical module includes: a first substrate configured to include an optical waveguide, and a first concave section provided over an end surface side of the optical waveguide; a resin configured to be disposed in the first concave section; an optical component configured to be disposed over the resin; and a second substrate configured to be jointed onto the first substrate, and to include a second concave section corresponding to the end surface in a surface facing the first concave section, the optical component being disposed between the resin and the second concave section.

A technology has been known in which a groove is formed in a substrate on which an optical waveguide is disposed in an optical axis direction of the optical waveguide, an optical component is adhered to the groove by using a resin, and an optical module is obtained. For example, a method has been known in which a silicon substrate is used as the substrate, a groove is formed by an anisotropic etching, and an optical component such as a lens is adhered to the groove by using a resin.
Japanese Laid-Open Patent Publication No. 2006-10959 and Japanese Laid-Open Patent Publication No. 2005-234052 are examples of the related art.
In the optical module using the technology described above, the dimension of the groove formed in the substrate to which the optical component is adhered, the amount of resin used for adhering the optical component, thermal expansion of the resin due to heat at the time of using the optical module, and the like may be a cause to provoke a positional deviation of the optical component from a predetermined optical axis. In the optical module in which the positional deviation of the optical component occurs, sufficient optical coupling efficiency may not be obtained.
According to the disclosed technology, a positional deviation of an optical component is suppressed, and an optical module having sufficient optical coupling efficiency may be realized. In addition, an optical device including such an optical module may be realized.

Optical module, manufacturing method of optical module, and optical device


The present invention provides a digital camera for recording image data to a recording medium, which includes an image signal processor, a recording and reproducing unit having an Optical Pickup unit, and a control unit for managing files having a sequence of data stored therein based on a virtual allocation table showing correspondence between actual addresses indicative of recording positions of the files on the recording medium and virtual addresses indicative of virtual recording positions of the files. When interruption of recording processing of data due to discontinuance of drive power supply, uncovering of a cover, impact, etc. is detected, the control unit retrieves and reads out restoration file information, and restores a file whose recording processing is interrupted based on the restoration file information.

As an optical recording medium which can optically read out data, a disc-shaped recording medium (referred to as optical disc, hereinafter) such as a CD (Compact Disc) has been used. This kind of optical disc has large storage capacity and can realize random accessing. In reading out data which is optically recorded on an optical disc, since an optical read-out unit is not brought into contact with an optical disc, there is caused little fear that the recording medium and optical read-out unit are caused to be worn out or damaged due to contact between the recording medium and optical read-out unit, which may be raised in the case of using a magnetic tape as a recording medium. Since an optical disc has a protective layer made of synthetic resin formed on a surface thereof so as to protect the signal recording layer, there is little fear that data is lost by mistake as compared with the case using a magnetic tape. So, an optical disc which has much advantage as compared with a recording medium such as a magnetic tape is an excellent recording medium adopted for storing data processed in an information processing apparatus such as a personal computer.
Recently, recording and reproducing apparatuses using an optical disc capable of recording data such as a CD-R (Compact Disc-Recordable), CD-RW (Compact Disc-Rewritable) have been developed. Among those, there are recording and reproducing apparatuses which can easily perform writing processing corresponding to all standard formats used in compact discs such as a CR-ROM, CR-ROM/XA, CD-I, CD-DA. Having replaced a conventional magnetic tape or magnetic disc, a CD-R is arranged in a electronic apparatus and is used as a recording medium for recording data processed in the electronic apparatus.
As a standard concerning recording and/or reproducing data using an optical disc, there is known the UDF (Universal Disc Format) established by the OSTA (Optical Storage Technology Association) of the United States.
A recording medium conforming to the UDF employs the packet writing in writing data. Employing the packet writing, data is written in the packet configuration in which one link block and four Run-In areas are arranged before the data area and two Run-Out areas are arranged after the data area. So, seven blocks other than the data area are used as linking recording areas (referred to as Linking Area, hereinafter) being linking areas between adjacent packets.
In a file system conforming to additional recording of the UDF, management information of a directory and a file is indirectly managed using an FID (File Identifier Descriptor), a VAT (Virtual Allocation Table), a File Entry ICB (File Entry Information Control Block), etc., instead of being directly managed using a real recording position (real address).
The VAT is a technique to manage real addresses where files are really recorded and virtual addresses corresponding to the real addresses, forming a correspondence table. Employing the VAT, when additionally recording data to a recording medium, the recording medium is processed as if its arbitrary address on the recording medium is accessed so as to update or reproduce data.
That is, in the UDF, position information of directories and files is indirectly referred to. The VAT is freely arranged in the packet configuration, while a VAT ICB (Virtual Allocation Table Information Control Block) indicating the VAT is necessarily arranged at a position returning from the final sector recorded on a recording medium by the Linking Area. So, in the UDF, virtual addresses can be converted to real addresses by reading out the VAT indicated by the VAT ICB.
In the UDF, a string of logical sectors in which writing/reading out of data is performed is referred to as an extent, and start addresses of respective extents are retained as file information and are additionally recorded together with file system information to be updated.
Generally, in additionally recording image file data etc. to an optical disc, after image data is written, following a sequence of image data object, file information concerning the sequence of image data is written, as has been described above. So, since file information and file system information is recorded to the end of an extent, the file information and file system information cannot be recorded to a recording medium such as an optical disc unless writing processing of image data object is finished. In case there is no file information and file system information, or in case file information and file system information cannot be read out, since a reproducing apparatus cannot recognize a recording medium itself or respective data recorded on the recording medium, the recording medium cannot be used.
For example, in case of a recording medium such as a CD-R, when recording processing is interrupted due to discontinuance of drive power supply, uncovering of a cover arranged at a recording and reproducing apparatus which veils a recording medium, impact, etc. during recording processing, recording processing of file information cannot be completed. Thus, data which is recorded until recording processing is interrupted is caused to be unreadable, or an optical disc itself may be broken.
To cope with the situation in which thus recorded data is caused to be unreadable, there is proposed a restoration processing which restores such unreadable data to make the data readable to a certain extent. For example, there is a conventional restoration processing which retrieves file information forward and rerecord information in which damage is found. Employing this method, damaged data may be restored to be of the state before writing, while data which is interrupted during writing processing cannot be restored. That is, under the conventional restoration processing, once writing processing is interrupted, there is raised a problem that thus interrupted data cannot be accessed.
Furthermore, the larger the size of data such as a moving picture file or non-compressed still picture data becomes, the longer it takes to perform writing processing. Thus, there is raised much possibility of interruption of writing processing due to accidental factors during writing processing. Moreover, the larger the size of data becomes, the more lost data there is necessarily raised when writing processing is interrupted.
Especially, in case of recording original data which is not stored in advance, that is, recording real time data of such as moving pictures which is directly supplied from an image capturing apparatus, when an accident such as interruption of writing processing happens, not only data which is recorded during the interruption of recording processing is lost, but also data which is recorded before the interruption of recording processing is undesirably caused to be unreadable.

Data recording/reproducing apparatus and data recording/reproducing method


The mechanical seal for a compressor comprises a support member fixed to a rotary shaft for rotating therewith, an annular rotating slide member consisting of hard materials and being fitted to the support member by shrinkage, and a stationary slide member exerting pressure against an end surface of said rotating slide member. In order to prevent damage by shrinkage stress and a displacement of said rotating slide member, said rotating slide member comprises at least one peripheral recess formed by a portion of the periphery of said rotating slide member having a smaller outer diameter than the rest of the periphery and said support member comprises an inwardly extending fitting portion engaging the peripheral recess.

The present invention relates to a mechanical seal for a compressor and to a centrifugal compressor comprising the mechanical seal.
A conventional mechanical seal which is used for providing a seal between a casing and a shaft of a centrifugal compressor will be explained by means of FIG. 7 which shows the cross-sectional view of the main part of the conventional mechanical seal.
Two annular rotating slide members 33 are attached to an annular support member 32 by shrinkage. The outer end surface 36 of each slide member 33 forms a sliding surface which contacts an opposed stationary slide member 34 exerting an appropriate pressure on the rotating slide member 33. The rotating slide member 33 and the stationary slide member 34 prevent fluid from leaking out of a centrifugal compressor at the sliding area. The outer diameter of the rotating slide member 33 is constant.
In order to determine the appropriate load for shrinkage fitting the stiffness of the materials of both slide members are to be taken in consideration. The slide members are required to have low friction at the slide surfaces thereof. Because a corrosive gas such as hydrogen sulfide is often dealt with, the slide members have to be resistant against corrosion. Finally the wear has to be small so that the slide members can be used for a period of at least 2 to 3 consecutive years.
For the above mentioned reasons hard materials such as the SiC (silicon carbide) are appropriate for the slide members. However, silicon carbide is a brittle material so that when an excessive load is applied to the slide members, cracks may occur at the surface of the slide members.
On the other hand, after shrink-fitting the rotational slide member 33 and the support member 32 of the conventional mechanical seal of FIG. 7, the rotational slide member 33 is supported at its periphery at the edge 38 of an inwardly extending fitting portion 37 of the support member 32. Therefore, the shrinkage stress acts at an extremely small portion of the periphery of the rotational slide member 33. This causes a stress concentration at a contacting area of the rotaional sliding member 33 and the support member 32 which can generate a cracks on the outer surface of the rotating slide member 33.
In order to reduce the stress concentration it can be considered to round the edge 38 of the fitting portion 37 of the support member 32 as shown in FIG. 6.
However, the rounding of the edge 38 does not prevent the rotating slide member 33 from displacing in axial direction. It is further necessary to consider the additional radial stress which is caused by centrifugal forces.
The shrinkage stress becomes greater when the centrifugal compressor is operated at a higher speed. As the maximum shrinkage fitting load may not exceed a certain value, the shrinkage fitting load for installation has to be below a proper value.
Therefore, an axially displacement or falling out of the rotating slide member 33 may occur due to a lack of supporting force when an impact force is applied to the centrifugal compressor from outside during operation or installing thereof.
Further, when the above-described slide members are used in centrifugal compressor having a rated rotational speed of 5000-20000 rpm, a shaft power of 300-8000 kW, a shaft diameter of 100-200 mm and a seal pressure of 0.5-2 MPa, the peripheral speed of the supporting portion becomes large and the supporting member 32 may deflect by the centrifugal force. Therefore, a radial outward displacement of the rotating slide member 33 occurs. This displacement causes a decrease of the amount of interference between the rotating slide member 33 and the support member 32 during operation.
To overcome this inconvenience, it is needed to provide a larger amount of interference for shrinkage fitting in advance.
In the Japanese Utility model laid-open 5-3737/1993, a mechanical seal made of ceramics is described. Though this seal has a face plate having a shoulder made of ceramics, it merely shows protection of debris coming into the seal region and does not show details how to use in a centrifugal compressor.
It is the problem underlying the present invention to provide a mechanical seal which eliminates the above-mentioned inconveniences of the prior art, can be manufactured or processed easily and has a high reliability.
Further a centrifugal compressor with a high speed and a high reliability seal is to be provided.
This problem is solved by a mechanical seal for a compressor comprising a support member fixed to a rotary shaft for rotating therewith, an annular rotating slide member consisting of hard materials and being fitted to the support member by shrinkage; and a stationary slide member exerting pressure against an end surface of said rotating slide member; wherein said rotating slide member comprises at least one peripheral recess formed by a portion of the periphery of said rotating slide member having a smaller outer diameter than the rest of the periphery; and said support member comprises an inwardly extending fitting portion engaging the peripheral recess.
Advantegeously at least one of the edges of the fitting portion is rounded.
When the mechanical seal is used for a centrifugal compressor having a rotating shaft with a diameter of 100-200 mm, a rated rotational speed of 5000-20000 rpm, a shaft power of 300-8000 kW and a seal pressure of 0.5-2 MPa, the outer diameter of the bottom of the peripheral recess is preferably smaller than the outer diameter of the rest of the periphery by 0.01-0.1 mm and/or the rounded edge of the fitting portion preferably has a radius of curvature of 0.05-0.2 mm.
In a preferred embodiment said rotating slide member has an increased heat transfer area.
Conveniently said rotating slide member is made of silicon carbide.
The mechanical seal of the present invention has a high reliabilty and a simple construction. Therefore it is easy to manufacture.
A centrifugal compressor operated at a rated rotational speed of 5000-20,000 rpm and a seal pressure of 0.52 MPa and including a rotating shaft having an outer diameter of 100-200 mm preferably comprises a mechanical seal of the present invention to have a high reliability.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

Mechanical seal for a compressor and centrifugal compressor comprising the mechanical seal


Laser conversion systems and methods for converting laser systems for operation in different laser safety classification modes are disclosed herein. In one embodiment, a laser system includes a laser configured to emit radiation greater than about 5 mW and an exterior housing containing the laser. The exterior housing has a section configured to be in a first arrangement in which the laser system is classified as a class I system and a second arrangement in which the laser system is classified as a class IV system. The laser system further includes a conversion module operably coupled to the laser system and the section. The conversion module is configured to enable one or more regulatory features required for class IV operation of the laser system when the section is in the second arrangement and disable the regulatory features required for class IV operation of the laser system when the section is in the first arrangement.

Lasers are ubiquitous devices used for testing, measuring, printing, cutting, marking, medical applications, communications, data transmission, semiconductor processing, and many other applications. Many types of lasers have been developed to meet different performance criteria for different applications. Engraving, cutting, marking, printing and many other applications require relatively compact lasers that generate high power output and have beams with a desired shape and energy distribution. Accordingly, equipment containing a source of laser radiation is required by law in most countries to meet certain safety standards in order to protect the user and others from exposure to the laser beam. These safety standards generally classify lasers and laser systems by the amount of laser radiation to which a user could be exposed during normal operation and maintenance. The classifications, as defined by federal and international regulatory agencies, range from class I through class IV, in order of increasing hazard.
Class I laser systems, for example, are designed to ensure that a user has no exposure to laser radiation. All laser radiation is contained within a light-tight enclosure made from one or more materials designed to withstand direct exposure to the unfocused laser beam contained inside the enclosure for an indefinite amount of time. Some examples of class I laser systems include laser printers, CD players, and CD-ROM devices. No safety precautions are needed to operate class I laser systems. Class II laser systems (e.g., laser pointers for presentations, consumer aiming/leveling devices, and range finding equipment) contain visible light, lower power lasers (i.e., less than 1 mW), and class IIIa laser systems (e.g., laser pointers and laser scanners) contain continuous wave, intermediate power lasers (i.e., 1-5 mW). Direct viewing of class II and class IIIa laser beams can be hazardous to a person's eyes, but the human blink reflex is generally expected to provide adequate protection for users of such systems.
On the other hand, class IIIb and class IV laser systems can be hazardous to users and, therefore, a number of different safety measures must be taken when using such systems. For example, class IIIb laser systems (e.g., spectrometers, stereo lithography equipment, and entertainment light show equipment) contain intermediate power lasers (i.e., continuous wave 5-500 mW or pulsed 1-10 J/cm2), and direct viewing of class IIIb laser beams, as well as diffuse reflections of such beams, are hazardous to a person's eyes. Therefore, appropriate safety precautions and proper eye protection are required for users of class IIIb lasers.
Class IV laser systems (e.g., laser surgery equipment, lasers used in research settings, laser drilling, welding and cutting equipment, etc.) contain high-power lasers (i.e., continuous wave greater than 500 mW or pulsed greater than 10 J/cm2). The direct beam and diffuse reflections from class IV lasers are hazardous to both the eyes and skin. Class IV laser systems can also be a fire hazard, depending on the reaction of the target material when struck by the beam. Accordingly, much greater controls are required to ensure the safe operation of class IV laser systems. For example, proper eye protection is required at all times and, depending on the wavelength, skin protection may also be required. In addition, areas in which class IV laser systems are used must be secured to allow the system's owner/operator to restrict access to the laser system since the operator and any bystanders could be exposed to the laser beam. Facilities in which class IV laser systems are operated are required by law (e.g., international, federal, and/or state) to follow certain laser safety protocols. Such protocols can include, for example, training and appointing a laser safety officer to oversee installation and operation of class IV laser systems, operating class IV laser systems in restricted areas with interlocked or secured entrances that shut off the laser whenever any entrance is opened, providing ongoing safety training for all users of class IV laser systems, ensuring proper eye/skin protection is provided for all users of class IV laser systems, and providing regular eye tests for all users of such systems. The owner/operator of a class IV system is also generally responsible for registering the system with the appropriate governmental agency, paying the necessary fees to the agency or appropriate entity, and regular recording of certain operational information. Manufacturers and distributors of class IV laser systems are responsible for informing potential purchasers about the dangers and responsibilities of owning and operating class IV laser systems, and the purchaser is then responsible for implementing and following all of the required safety protocols.
Many class I laser systems used for material processing (e.g., cutting, marking, welding, etc.) contain lasers powerful enough to be classified as class IV; however, the beam is contained in an exterior housing or enclosure configured in such a way that the overall system can be classified as a class I laser system. Accordingly, openings to the housing, such as doors and hatches meant to be opened during normal operation and maintenance, must be redundantly interlocked to ensure that the laser is shut off or the beam is effectively blocked when any of these doors or hatches is opened.
One drawback with such laser systems, however, is that the arrangement of the housing can significantly limit the size of workpieces that can be placed within the system for processing. For example, most class I laser systems that include high-power (e.g., class IV) lasers are configured to only process workpieces that fit entirely within the housing because the interlocks on each door of the housing must remain engaged or otherwise activated to maintain class I operation of the system. In some cases, however, a user can defeat or otherwise deactivate the interlocks on one or more of the doors to allow a portion of an oversized workpiece to be positioned within the housing for processing. In such cases, the user has effectively nullified the laser system's safety features and turned a class I system into a potentially hazardous laser system with no classification. Furthermore, the system's user/operator was not likely informed of the dangers and responsibilities associated with operating a class IV laser system because the laser system was sold or provided as a class I laser system, and manufacturers/resellers of class I systems are not required to provide such information. Although many manufacturers of class I laser systems that include high-power lasers make reasonable efforts to prevent interlocks on the system's housing from being compromised and/or defeated, a significant number of conventional laser systems include safety features that are relatively easy to defeat and, furthermore, many manufacturers turn a blind eye to such issues.

Laser conversion systems and methods for converting laser systems for operation in different laser safety classifications


Various example embodiments are disclosed relating to efficient techniques for error detection and authentication in wireless networks. For example, according to an example embodiment, an apparatus adapted for wireless communication in a wireless network may include a processor. The processor may be configured to transmit a message including a field to provide both authentication and error detection for the message. The field may include an authenticated checksum sequence.

A number of different wireless networks have been developed. One of the most common wireless technologies is wireless LAN (wireless local area network) or WLAN technology. An example WLAN technology is described in the Institute of Electrical and Electronics Engineers IEEE 802.11 family of industry specifications, such as specifications for IEEE 802.11b, IEEE 802.11g, IEEE 802.11a and 802.11n, etc. A number of different 802.11 task groups are involved in developing specifications relating to improvements to the existing 802.11 technology. Other wireless technologies are being developed, such as IEEE 802.16 or WiMAX technology. A variety of other wireless networks exist, such as cellular networks and the like.
Errors may sometimes be introduced during transmission via a wireless or other medium. A number of different techniques have been employed in attempt to detect errors. For example, a checksum is sometimes calculated and appended to a message at a transmitting node to allow a receiving node to detect errors in the received message.
Authentication is also sometimes employed to allow a receiving node to confirm that a received message was sent by an alleged sending node, and not sent from another node (e.g., an attacker or other node pretending to be the alleged sending node). A number of different security techniques have been employed to allow authentication of messages or between nodes.
Unfortunately, in some cases, techniques that attempt to provide error detection or authentication in networks may introduce significant overhead.
For example, in IEEE 802.16, error detection for a frame body may be provided by a one byte checksum. In addition, with respect to security or authentication, a Hashed Message Authentication Code and Cipher-based Message Authentication Code (HMAC/CMAC) tuple may be provided in some messages, which may introduce significant overhead for messages.
It may be desirable to provide more efficient techniques to provide error detection and/or authentication.

Efficient techniques for error detection and authentication in wireless networks