Methods and apparatus for recovering dental pulp from dentition of a donor are disclosed, wherein the pulp from within extracted teeth utilizing such methods and apparatus is harvested, while preserving a sterile environment and avoiding trauma and infection, and stem cells, dendritic cells, and other cells isolating from the pulp, and the various cells propagated and expanded for subsequent use in repair or regeneration of tissues of the body, for therapeutic treatments, and other medical purposes.

The present invention relates generally to methods and apparatus for recovering dental pulp from dentition of a patient or other donor, in order to use the pulp so secured, and the stem cells and other cells contained in the pulp, for beneficial medical purposes. More specifically, the present invention relates to a method of obtaining dental pulp from teeth at times and under conditions most suitable, such as during normal tooth loss of xe2x80x9cdeciduousxe2x80x9d teeth. At such times teeth may be taken, and the pulp from within the teeth extracted or xe2x80x9charvested,xe2x80x9d while preserving a sterile environment to avoid contamination of the pulp and, at the same time, avoiding trauma and infection of the donor. The pulp so secured may be utilized by isolating from it xe2x80x9cstem cells,xe2x80x9d which may exhibit an ability to differentiate into cells of the same or other types, or propagated and manipulated to exhibit such xe2x80x9cplasticity,xe2x80x9d for subsequent use in repair or regeneration of the same or other tissues of the body. The pulp may also be utilized by isolating from it other kinds of cells, such as dendritic cells which may exhibit an ability to detect hostile proteins foreign to a patient""s body, for subsequent use in therapeutic treatments.
In recent years, scientific interest has increased in cell biology in the areas of the derivation of cells, and the ability of certain cells to differentiate into cells of specific tissues. A broad interest in these areas dates back to the first report of animals produced by in vitro fertilization (xe2x80x9cIVFxe2x80x9d) in 1959, through the first report of the first fertilization of a human egg by IVF in 1968, and the report of the first IVF baby born in England in 1978. However, as a result of interest in developing innovative cell replacement strategies to rebuild tissues and restore critical functions of the diseased or damaged human body, some studies in these areas have more recently focused on the derivation and culturing of xe2x80x9cstem cells,xe2x80x9d and more particularly on human stem cells.
A stem cell is a cell that has the ability to divide (self replicate) for indefinite periods, often throughout the life of the organism. Under the right micro-environmental conditions, or given the right signals, stem cells can give rise (xe2x80x9cdifferentiatexe2x80x9d) to the many different cell types that make up the organism. That is, stem cells have the potential to develop into mature cells that have characteristic shapes and specialized functions, such as heart muscle, skin cells, hepatic tissues, or nerve cells.
It is widely recognized that a fertilized egg may generate all the cells and tissues that make up an embryo and that support its development in utero. The fertilized egg divides and differentiates until it produces a mature organism which, in mammals, requires the division of cells and their differentiation into more than 200 kinds of cells in the mature organism. These kinds of cells include nerve cells (neurons), blood cells (such as erythrocytes, monocytes, lymphocytes), and bone cells (osteocytes). xe2x80x9cPluripotentxe2x80x9d stem cells can give rise to cells derived from all three embryonic germ layers (mesoderm, endoderm, and ectoderm) of an embryo, and much attention has therefore been focused recently on pluripotent stems cells from organisms at early stages of embryonic development. However, ethical concerns have been raised about the use of embryonic cells. As a result, adult (i.e., not embryonic) stem cells have taken on more importance as a source for stem cells for developing innovative therapeutic strategies.
An adult stem (xe2x80x9cASxe2x80x9d) cell is an undifferentiated (unspecialized) cell that is found in a differentiated (specialized) tissue; it can renew itself and become specialized to yield all of the specialized cell types of the tissue from which it originated, and possibly other specialized cells. AS cells are capable of self-renewal for the lifetime of the organism. Cells capable of differentiating along only one lineage (i.e, xe2x80x9cunipotentxe2x80x9d cells, which allow a steady state of self-renewal), have been assumed for most tissues of adults until recently. Adult bone marrow cells, for example, have been known and used for decades in transplant therapies. However, even tissues containing only unipotent cells may be repaired if the tissue becomes damaged. When replacement of multiple cell types is required, pluripotent stems cells may become activated to repair the damage. Thus, for several decades stem cells harvested from skeletal bone marrow have been used in therapy in cases of cancer, aplastic anemia, lymphomas, and other life-threatening diseases. Sometimes marrow is transplanted directly from a donor to a patient requiring rescue therapy, and sometimes it is first preserved for a time in liquid nitrogen prior to transplantation.
It was not until recently that researchers have considered the possibility that stem cells in adult tissues could generate the specialized cell types of another type of tissue from that in which they normally reside. However, recent studies have demonstrated that blood stem cells (derived from bone marrow) may be able to generate both skeletal muscle and neurons. This facility of AS cells to generate specialized cell types of another type of tissue has been variously referred to as xe2x80x9cplasticity,xe2x80x9d xe2x80x9cunorthodox differentiation,xe2x80x9d or xe2x80x9ctransdifferentiation.xe2x80x9d Presently, there is evidence that AS cells can generate mature, fully functional cells, or that the cells have restored lost function in vivo. Collectively, studies on plasticity suggest that stem cell populations in adult mammals are not fixed entities, and that after exposure to a new environment, they may be able to populate other tissues and possibly differentiate into other cell types.
Most studies on plasticity show plasticity in adult stem cells involving cells derived from bone marrow or brain tissue. Bone marrow appears to contain three stem cell populations, hemoatopoietic stem cells, bone marrow stromal cells, and (possibly) endothelial progenitor cells. Bone marrow stromal cells are a mixed cell population of cells that generate bone, cartilage, fat, fibrous connective tissue, and the reticular network that supports blood cell formation (mesenchymal stem cells of the bone marrow also give rise to these tissues, and may constitute the same population of cells as the bone marrow stromal cells). Studies of hematopoietic stem cells from bone marrow demonstrate an ability to regenerate an entire tissue system, i.e., all cell types found in blood. Thus, bone marrow shows promise as a source for AS cells exhibiting plasticity, and further development of materials and techniques may allow the utilization of all three stem cell populations found in bone marrow.
Efforts are now underway to take advantage of the newly found capability of adult stem cells, with the goal of devising new treatments for disease and disability. Medical science is now providing voluminous evidence of many potential uses for stem cells, such as organogenesis, gene therapy, anti-aging therapies, angiogenesis, organ and tissue repair (particularly in cases of nerve damage), and the treatment of brain tumors, liver disease, and other diseases. AS cells from marrow may now be treated with certain chemicals such as dimethyl sulfoxide (DMSO) and hetastard with PBS, cryopreserved in liquid nitrogen, and later removed, thawed and used for transplantation and other therapies. Today there is new evidence that AS cells may be found in more tissues and organs than previously thought, and that these cells are capable of developing into more kinds of cells than previously imagined. Efforts to devise new treatments for disease and disability utilizing AS cells hold great promise for the future if AS cells may be (i) secured from tissues of the body in a safe, painless, and convenient way, (ii) secured in acceptable quantity, (iii) isolated, (iv) propagated and aggregated (xe2x80x9cexpandedxe2x80x9d via cellular division) to numbers useable for tissue regeneration, (v) and adapted to generate cell types of another type of tissue from that in which they normally reside.
The present invention is directed to the identification of a source of AS cells and other cells within a tissue and organ of the body, and a method for removal of such cells safely and conveniently, by a means which maintains a sterile field, so that the cells may be set aside for isolation, and in such quantity as to be use for propagation to numbers and forms usable for tissue regeneration. Such removal of cells from the body using the present invention takes place under circumstances which offer the minimum of discomfort, is maximally safe, and may in most cases be undertaken in the normal course of body growth and tissue replacement. The present invention is also directed to an apparatus useful for accomplishing the method of the invention. More specifically, the present invention is directed to the identification of teeth as a source of a variety of cells useful for therapeutic purposes (AS cells and other cells useful for medical purposes, such as dendritic cells and precursor cells, collectively xe2x80x9cUseful Cellsxe2x80x9d), the removal of teeth under controlled conditions to preserve sterility, and the further removal of the pulp within such teeth (these processes collectively, xe2x80x9cHarvestingxe2x80x9d), so that Useful Cells within such teeth may be subsequently isolated and utilized for tissue repair or regeneration.
A number of schemes have been devised to extract human bone marrow. Such schemes employ methods and apparatus applied at various locations of the human skeleton or soft tissue. Published scientific papers, including the recent paper from the National Institute of Health entitled Stem Cells: Scientific Progress and Future Research Directions (June 2001), indicate that sources of AS cells include bone marrow, peripheral blood, blood vessels, the cornea and the retina of the eye, brain, skeletal muscle, dental pulp, liver, skin, the lining of the gastrointestinal tract, and pancreas. Methods and apparatus have been developed to remove stem cells from some of these areas of the human body. As to removal of stem cells from bone material specifically, such methods and apparatus include:
U.S. Pat. No. 5,913,859 to Shapira, which discloses an apparatus for extracting bone marrow from the jawbone of a patient before, during, or after dental procedures.
U.S. Pat. No. 6,110,176 to Shapira, which discloses a method for extracting bone marrow from the jawbone of a patient before, during, or after dental procedures.
In addition, bone marrow collection for transplantation purposes is often accomplished by inserting a needle into a donor""s hip or pelvic bone. A needle is inserted into the bone approximately 25 to 30 times through several small incisions made in the pelvic area. Each insertion of the needle takes a xe2x80x9ccore,xe2x80x9d which may be aspirated through the needle. The extraction process typically lasts at least one hour or more, or until approximately 1,000 to 1,500 milliliters of the donor""s marrow and blood is withdrawn. The donor of the donated marrow requires hospitalization, but may recover fully in a few weeks after the procedure. However, the extraction process is painful, and the patient may feel fatigued for a period of time after the procedure is performed. Further, the procedure requires general anesthesia in an operating theater. This type of device is also frequently used at bedside as a means of taking small biopsy samples using a single coring of the ilial crest. Bone marrow may also be obtained by similar methods from the sternum, or from long bones such as the tibia or femur in adolescents, or other methods having similar drawbacks.
Thus, there is a need for extraction methods that avoid the considerable inconvenience and discomfort of current methods, and apparatus to accomplish such methods, so that AS cells may be secured for use, and for isolation and propagation of AS cells for the medical benefits to be derived for donors and other patients. While the inventions disclosed in these prior patents, methods, and articles fulfill their respective objectives, these prior patents do not describe or suggest a method or apparatus designed to utilize AS cells, and other cells, found in teeth. These prior methods and apparatus of the prior art are directed to securing bone marrow from skeletal tissues, including areas of the skeleton closely associated with dentition, but not from the dentition itself. That is, nothing in the prior art refers to any method for obtaining tissue from teeth in order to produce AS cells for tissue repair or replacement, or other purposes (such as research). No apparatus of the prior art is constructed to achieve this result. Further, the prior art, to the extent it is used to secure marrow from bone, is directed to main skeletal components only, that is iliac (pelvic) bones, long bones, the skull, and connective tissues, all of which tissues the body must replace or repair after marrow is removed. Accordingly, no prior method of marrow removal may be employed without some trauma and increased risk to the donor or patient, or both. Using the method of the present invention, on the other hand, a user may conveniently secure tooth pulp from a patient at the time of normal tooth loss during growth, or during dental work in which teeth are removed, or routinely maintained (such as drilling for a xe2x80x9croot canalxe2x80x9d), which patient may then receive the benefits derived from that pulp, including any benefits derived from his or her own AS and other cells. Significantly, a user may, using the method of the present invention, take tooth pulp, from which AS cells may be secured, and apply those cells which may exhibit plasticity to the benefit of other individuals, and to the repair or regeneration of a variety of tissue types within the donor or such other individuals.
Moreover, the pulp secured from the donor""s teeth may be utilized by isolating from it dendritic and other cells, which may then be utilized in therapeutic treatment for their ability to detect hostile or foreign proteins. Further, AS cells may be a particularly good source of genetic material for gene therapy (in, e.g., the production of xe2x80x9cgenomic pharmaceuticalsxe2x80x9d), and in genotyping for donor registration and donor matching. Finally, teeth are not affected by the soft tissue or hard tissue tumors of other parts of the body, including tumors of the jaw, even after metastasis of such tumors. Accordingly, it may be possible to take teeth from a patient prior to administering chemotherapy or radiotherapy in the treatment of cancer in other parts of the body. It may then be possible to autograft the expanded AS and other cells harvested from those teeth back into the patient. By such a procedure, it may be possible to thereby reintroduce into the patient his or her own xe2x80x9cfresh,xe2x80x9d non-cancerous regenerative cells. Such cells, as with bone marrow xe2x80x9crescuexe2x80x9d therapy, have not have been exposed to the damaging effects of chemotherapy and radiotherapy, and so are unaffected by such therapies. However, such cells are less likely to have tumorous or metastasized tissues which could then repopulate the patient. All such benefits are derived from the present invention, which provides for securing AS and other cells without trauma, usually at a time convenient to the donor, and generally in a sterile field without significant possibility of contaminating the cells so secured.
In this respect, the method of the present invention substantially departs from pre-existing methods of the prior art, and all apparatus associated with methods of the prior art, and in so doing provides the user with a means for harvesting stem cells (and other cells which may be found in teeth and applied for medical purposes) from the pulp of teeth. By using the invention disclosed herein, users gain the highly desirable ability to secure AS cells for present or future use for tissue regeneration or replacement, while avoiding trauma and long recovery, contamination of the pulp, risk of infection of and by the donor, and other problems associated with extracting marrow from other parts of the body.
The present invention overcomes the problems and disadvantages of the prior art by utilizing pulp from teeth, a location from which AS cells (and other cells) have not before now been obtained for medical purposes.
A normal tooth contains living tissue known as xe2x80x9cdental pulp.xe2x80x9dThis tissue occupies a canal extending from the apex of the tooth root (or roots), where it communicates with the bone in which the tooth is anchored (the mandible on the lower part of the mouth, and the facial maxillae on the upper part of the mouth), to the area immediately under the crown of the tooth. The canal in each tooth is relatively narrow in and near the root apex, but widens out near the crown into a pulp chamber, which is an enlarged area accommodating a larger volume of dental pulp than is present in the root. The pulp chamber is therefore the location of the great majority of the dental pulp of the tooth. The volume of dental pulp within the pulp chamber contains sufficient dental pulp to be useful in the process of extracting pulp to obtain the AS cells residing there (or xe2x80x9cHarvestxe2x80x9d or xe2x80x9cHarvestingxe2x80x9d such cells) for medical use (and other cells). Locating and Harvesting dental pulp from teeth, and particularly the pulp chamber of teeth, for isolation and use of AS cells and other useful cells, is the purpose and object of both the method and apparatus of the present invention.
Dental pulp comprises nerve tissue, blood vessels, lymphatic tissue, mesenchymal tissues, and, possibly, hematopoietic tissues. Mesenchymal and hematopoietic tissues are known to contain Useful Cells (stem cells, dendritic cells, precursor cells, and [note to look up other known medically useful cells] cells useful for medical purposes), when found in other organs of the body. Such tissues are likely to contain such Useful Cells when found within the dental pulp. As noted above, stem cells harvested from skeletal bone marrow have been used in therapy, to counter disease and to provide tissues for generation of tissues for organ and tissue repair. Using the methods and (or) apparatus of the present invention, dental pulp is an additional source for obtaining AS cells and other Useful Cells and, therefore, Harvesting dental pulp provides an additional means for obtaining such cells.
Because of the small amount of pulp residing within a tooth, the quantity of Useful Cells obtained from individual teeth is quite small. However, recently several companies have devised methods for expansion of the number of AS cells by propagation, so that the numbers of such cells are useable for transplantation and other medical purposes. It may also be possible to combine the dental pulp from two or more teeth, extracted at the same or different times, in order to augment the quantity of cells. Thus, AS cells from dental pulp could be used to save lives and improve the health of both the individual from whom they came (by xe2x80x9cautologousxe2x80x9d transplant) after such propagation. For such patients, the pulp may be frozen and stored as set forth more fully below, or the pulp may be first processed to isolate Useful Cells, the AS cells then propagated and aggregated to numbers useable for tissue regeneration, and then cryopreserved in liquid nitrogen and stored. The AS cells may also be expanded by cellular division (xe2x80x9cpropagatedxe2x80x9d), and used immediately for therapeutic purposes. Accordingly, the dentition of a patient may become the source for AS cells which, once adapted to generate cell types of another type of tissue from that in which they normally reside (i.e., they exhibit xe2x80x9cplasticityxe2x80x9d), are useful for treatment of that patient""s disease, or his or her need for replacement or repair tissue. With sufficiently close histocompatibility (from a close relative for instance) or immunosupressive treatment, dentition taken from a non-patient donor may also become the source of AS cells for other patients (by xe2x80x9callogeneicxe2x80x9d transplant). However, the immediate need is for collection of AS cells and other Useful Cells for treatment of the patient-donor.
When a tooth is newly extracted by a dentist, oral surgeon or periodontist, or when a tooth is shed from its socket naturally, it carries with it the living dental pulp which may remain vital for some hours following the removal or release of the tooth, particularly if the tooth is stored under ice. Using the method of the present invention, following removal of a tooth from its socket, or following a natural loss of a tooth, the tooth is first placed briefly into a bath of alcohol or other sterilizing liquid medium. Such sterilizing medium is likely to be damaging to cells of many types, including the Useful Cells residing within the pulp chamber of the tooth, should the medium come into contact with that pulp. However, the sterilizing medium using the method and apparatus of the present invention will generally only come into brief contact with the tissue immediately within the opening of the canal or canals at the apex of the root. Because the opening at the root apex is small, and because the pulp is gelatinous and viscous, the sterilizing medium cannot move into, and so damage, the main part of the pulp found within root or the pulp chamber. Rather, only the exposed surface tissue located at the apex of the tooth root may be damaged by exposure to the medium. As to such surface tissue and bacteria, all or virtually all cells are killed. Thus, the sterile field present at the root tip prior to tooth extraction is preserved or restored, or a sterile field at the root tip is produced if the area of bone surrounding the root apex was not already sterile while anchored in the donor""s mouth, or was contaminated as it passed out of its socket. At the same time, the exterior surface of the remainder of the tooth, which is generally teeming with bacteria, virus and fungi, is also sterilized by the sterilizing medium, as bacteria present on that surface (and everywhere on the exterior surface of the tooth) is exposed to the same sterilizing medium. As the main part of the dental pulp residing in the pulp chamber is already generally sterile, the result of placing a newly removed tooth into sterile medium is to produce a sealed (within the hard exterior tooth surfaces), sterile field around the tooth, within which is located sterile dental pulp. After achieving sterilization, the entire tooth may then be placed into a saline solution, Ringer""s, or other isotonic solution, thereby washing away or diluting the sterilizing medium and creating a barrier to further contamination. After it is diluted or rinsed away, the sterilizing medium is no longer present, and so cannot be absorbed into the pulp located away from the apex of the tooth root, nor can it seep into the pulp cavity through the root or through accessory canals. As access to the pulp within the pulp chamber and the root is generally only afforded through the root, preserving pulp within the tooth root against damage by rinsing away the sterilizing medium will also preserve the pulp within the pulp chamber distal to the apex of the root.
The preferred amount of time for a tooth to rest within a container of sterilizing medium will depend generally on the properties of the medium. At the least, the tooth should remain in the medium for a time sufficient to kill most bacteria normally found in the mouth. On the other hand, the tooth should remain in the medium for a time short enough to avoid significant pulp loss from the apex of the tooth root. The optimal time for a tooth to rest in a sterilizing medium may therefore be as little as one second, or as great as about one hour depending on the medium used. However, for alcohol as a medium, and with access to the pulp within the interior of the tooth only through the apex of the root assumed, the preferred time for a tooth to rest in a sterilizing medium falls within a range of approximately one (1) to five (5) minutes, depending on concentration.
Harvesting the dental pulp from a tooth requires dissecting or opening the tooth to reveal the pulp, or otherwise manipulating the pulp to remove it from the pulp chamber and root. In its simplest form, the method of the present invention comprises the steps of (1) removing a tooth from the mouth of a human, or gathering such a tooth as it is shed, (2) sterilizing the tooth, especially the part of the tooth near the apex of its root or roots, (3) dissecting the tooth by breaking it open, and (4) removing the tooth pulp from the hard exterior fragments of the tooth so dissected. While the present invention is specifically directed toward the benefits to be derived from human teeth, the methods and apparatus of the present invention may also be adapted to the same benefits in dogs, cats, mice, and other mammals.
It should be noted, however, that the removal of the pulp using the method of the present invention may take place at various times after a tooth is naturally shed or identified for removal, and various steps may be taken in the process of the present invention in various orders, at various places, and utilizing various tools and solutions. For example, once a tooth has been removed from the mouth of a donor and sterilized, the tooth may be placed in a cool, sterile medium for temporary storage. In such condition the Useful Cells may be utilized immediately, or within a few hours or days in the place where the tooth was removed (generally at a dentist""s office) or nearby (generally at a hospital or other location more suitable for medical procedures). At the location of use, then, the tooth may be opened utilizing the method or apparatus of the present invention, and the pulp then processed to isolate from it the AS and other Useful Cells. The Useful Cells may then be expanded via cellular division to numbers useful in the medical technique to be employed, and then introduced to a patient in an acceptable medical procedure. At the location of use, in the alternative, the dental pulp may be then frozen and stored for a longer period of time after the tooth is opened, or the Useful Cells obtained from the tooth may be isolated, expanded by propagation, and then frozen and stored. However, in these steps of the present invention, and in the further steps set forth below, every effort should be made to remove the pulp from the remainder of the tooth fragments within 12 hours, after such time the viability of the Useful Cells may be substantially reduced, and treatment using such cells compromised.
As a further example the timing of the removal of the pulp using the method of the present invention, once a tooth has been removed from the mouth of a donor and sterilized, the tooth may be immediately opened utilizing the method and apparatus of the present invention. Once the pulp is removed from the tooth fragments, the pulp may then be processed to isolate the AS and other Useful Cells from the connective tissue of the pulp, the Useful Cells expanded, and then used in treatment of a patient without transporting them to another facility or freezing them for long term storage.
As yet a further example the timing of the removal of the pulp using the method of the present invention, once a tooth has been removed from the mouth of a donor and sterilized, the tooth may be shipped in a sterile medium to a location for processing and storage, much as cord blood is now transported, treated, and stored at a location separate from both the donor and the patient-recipient. At such location, the tooth may be treated further and frozen, or it may be opened, treated, and the pulp frozen, or it may be opened, treated, the useful cells isolated, and those cells then expanded via cellular division. If the pulp is frozen, cell isolation and propagation may take place at a later time, and the cells so produced then shipped to a location for treatment of a patient. In some cases the cells may not themselves be used, but products of the cells may be used for treatment, such as in gene therapy. If the cells are expanded without freezing of the pulp, then the cells may be frozen and stored, or expanded by propagation and then frozen and stored, for later shipment to and use at a remote location for introduction into a patient. As the cells obtained from teeth using the method and apparatus of the present invention may be utilized to generate entire tissues, and perhaps organs, the cells may be placed within a process of growing such tissues and organs at any point in any of these processes once the cells are in a condition to begin the process of tissue generation. As growing tissues is generally done in a larger facility having the tissue generating capability, it may be convenient to conduct the steps of isolating AS cells, expanding by propagation, and tissue generation at the same centralized facility. Such variation in the series of steps of the present invention would be more typical of those steps taken at a central processing and storage facility, much as cord blood and its components is handled today. A generalized representation of the method of the present invention appears in the form of a flow chart as FIG. 1 appended hereto.
In any case, however, whether AS cells and other Useful Cells are used in the form of dental pulp, or as isolated cells, or as isolated and propagated cells, or as tissue or organs grown from such cells, or as products derived from any of the forgoing, all methods of identifying and producing Useful Cells should be considered to be part of the present invention if such cells are Harvested from teeth. Moreover, whether the cells are used early in their processing, as isolated AS cells for instance, or later in the process, as wholly grown organs for instance, all methods of producing Useful Cells should be considered part of the present invention regardless of the timing of such use if such cells are Harvested from teeth. Further, all methods which use AS cells and other Useful Cells, whether the cells are used fresh or they are frozen, whether the dental pulp is frozen, or the isolated cells frozen, or the propagated cells frozen, or the whole tissue frozen, and whether such cells are cryopreserved in liquid nitrogen as with skeletal marrow and cord blood, or otherwise preserved, should be considered part of the present invention if such cells are Harvested from teeth. Finally, whether the cells are used before freezing or after, or without freezing, before or after isolation or propagation or aggregation, or growth to entire organs, all methods of using the such cells should be considered part of the present invention regardless of the order of the steps taken to produce the desired type and number of cells, and regardless of the location of their isolation, propagation, aggregation, growth, or ultimate use, if such cells are Harvested from teeth.
Given the unusual nature and properties of teeth amongst the places from which Useful Cells may be obtained, it may be appreciated that the method of the present invention is particularly suited for collection and Harvesting of cells useful for treatment of disease, in tissue repair or replacement, or for the production of other beneficial products, such as pharmaceuticals, and in research. Collection may take place long before the need arises for pulp, AS cells, or other Useful Cells. Such early collection will take place, and is more likely to take place than by other means, during the process of tooth loss or tooth extraction. At such times the tooth is often easily lost or removed in the normal course of growth or in routine dental treatment, such as in the removal of teeth to make room for others, as in orthodontics, or to reduce the possibility of dental problems by prophylactically removing a patient""s third molars (so called xe2x80x9cwisdom teethxe2x80x9d extraction). With respect to children specifically, it is a medical axiom that the younger the stem cells used in therapy (for example xe2x80x9crescue therapyxe2x80x9d in cases of cancers), the better the therapeutic outcome. Harvesting the dental pulp of an 8-year old child and preserving it for later use could result in an improved outcome of from 30% to 45% over what would be the outcome were the marrow of a 38-year old donor used (the average age of donors in the United States). Moreover, by utilizing the methods and apparatus of the present invention, particularly as they relate to freezing for long-term storage, a donor-child may obtain and xe2x80x9cbankxe2x80x9d for use later in life Useful Cells from his or her own teeth at the time of normal loss of xe2x80x9cdeciduousxe2x80x9d teeth as a child. Thus, the process of collecting dental pulp, and the AS cells and other Useful Cells such pulp contains, is easily undertaken, and likely to become as common as routine dental work, particularly in children.
One embodiment of the apparatus of the present invention comprises a vessel into which a tooth may be placed. The bottom of the vessel in such embodiment is formed to create an elongated, generally xe2x80x9cv-shapedxe2x80x9d bottom, or a xe2x80x9ctroughxe2x80x9d with narrow bottom. The vessel may have within it a fluid, such as simple saline solution, Ringer""s, or other isotonic solution, for the protection of the tooth to be dissected, and the pulp within the tooth once dissected. As the method of the present invention requires the sterilization of the subject tooth with a sterilizing medium, the fluid within the vessel may provide such protection of the tooth by first providing a wash, or dilution of, the sterilizing medium. Additionally, when the tooth has been dissected, the pulp within the tooth would be exposed to air unless such a neutral solution is used to isolate the pulp from the environment. An isotonic solution, at normal body temperature or below, will preserve the now accessible pulp from dessication, contamination, or other damaging exposure to air. Accordingly, such an isotonic solution, in a quantity sufficient to cover the tooth prior to dissection should be used in conjunction with the apparatus of the present invention.
Two of the sidewalls of the vessel in such embodiment join the sides of the bottom. Accordingly, a tooth placed within the vessel will fall in response to gravity until it rests on the bottom of the vessel and, as the sides of the v-shaped bottom narrow and join near the elongated center of the bottom, the arrangement of sidewalls and v-shaped bottom of the vessel allow a tooth placed within the vessel to fall within the vessel until the tooth comes up against the opposite side of the bottom where the sides meet at the apex of the v-shaped bottom. In such position, the tooth will come to rest so that it falls to, and comes to rest within the apex of the bottom, and the tooth will in further response to gravity and the fluid within the vessel tend to come to rest so that the major axis of the tooth is oriented longitudinally, along and parallel to the length of the lowest portion of the v-shaped bottom, and as low within the trough as the width of the trough will allow. In such position, a tooth is in a good position to open evenly in response to pressure which may be exerted by the apparatus. In such position, the tooth is xe2x80x9cclampedxe2x80x9d into position by the v-shaped bottom so it cannot roll to the side of the bit, but the tooth fragments are free to fall aside and not damage or compress the pulp.
A wedge-shaped splitting bit is provided in the apparatus of the present invention, arranged to move within the vessel toward the apex of the bottom of the vessel. The bit is arranged so that it may so move until it bears against a tooth residing within the trough of the vessel""s bottom. The splitting bit may be shaped to fit tightly within the bottom of the vessel, the apex of the bit matching the apex of the trough, so as to run tightly along and within the corresponding length at the apex of the bottom trough. However, in other embodiments of the present invention, the angle at the edge of the splitting bit may be either more or less acute than the trough (i.e., the bit may narrow to an edge more quickly than the bottom of the trough at the bottom of the vessel), or it may present a relatively flat face toward a tooth residing at the bottom of the trough. In yet other embodiments, the bit may have projections which may extend from the leading edge or face of the bit, so as to apply pressure to a very small area of the tooth residing at the bottom of the trough.
The splitting bit is situated within the vessel when in use, and held tightly against movement perpendicular to the length of the trough at the bottom of the vessel. Such restriction of movement is accomplished in one embodiment by guide tracks running from a position near the opening of the vessel to a position near the bottom of the trough, which tracks constrain movement of the bit perpendicularly to the length of the apex of the trough. Within such tracks, the bit may, in one embodiment of the apparatus of the invention, travel toward the opening of the vessel a sufficient distance to allow a large tooth to come to rest within the trough, and also toward the apex of the bottom of the vessel a distance sufficient to allow the bit to bear against a small tooth. Other embodiments of the apparatus may be manufactured to accommodate different sizes of teeth.
The splitting bit is provided with a means for moving the bit both toward and away from the trough of the bottom of the vessel. In one simple embodiment of the present invention, the means for moving the bit is a supporting shaft formed to create a screw, having an exterior thread, upon the end of which the bit is mounted. In such embodiment, the mounting of the bit on the screw may be accomplished by fixing the bit on the end of the screw so that the bit and screw cannot rotate one against the other. In such embodiment, the screw is advanced toward the trough of the bottom of the vessel by the turning of a xe2x80x9cnutxe2x80x9d having complimentary (to the screw) interior thread, or by other means having complimentary thread which may engage the screw. The screw or the nut, or both, are appropriately held in position so that the nut may rotate and the screw may advance, but each such component is otherwise constrained. In another simple embodiment of the present invention, the screw means for moving and supporting the bit is rotatably mounted. In such embodiment, the screw is advanced toward the trough of the vessel by the turning of the screw within a nut having complimentary interior thread, or by other means having complimentary thread which may engage the screw. Again, the screw or the nut, or both, are appropriately held in position so that the screw may rotate and advance, but each such component is otherwise constrained.
In yet other embodiments of the apparatus of the present invention, the means for moving the bit is a supporting shaft formed to create a piston or push rod, which may be acted upon by a motor, a cam, a screw, or by hydraulic piston or other means for advancing the piston or push rod toward the trough at the bottom of the vessel. In all of the above arrangements the means for advancing the bit toward the trough at the bottom of the vessel may also be used to withdraw the bit from the trough a distance sufficient to allow the placement of a (large) whole tooth in the apparatus for dissection, and sufficient to allow removal of pieces of the tooth so dissected. All of the above arrangements may also be accomplished without the use of guide tracks if the bit is, except for advancing toward and from the trough of the bottom of the vessel, sufficient constrained against other movement by other appropriate means. Such other means must constrain the bit against movement perpendicular to the advance and withdrawal of the bit, and also restrained against rotating within the vessel.
Most embodiments of the apparatus of the present invention provide, in the means for advancing the bit toward the trough, means capable of generating sufficient force to break a tooth open when the bit is urged against the tooth. By use of such force, a whole tooth may be fractured into two or more pieces, revealing the dental pulp residing within the tooth, and making that pulp accessible to a user for further processing. Such apparatus may be as simple as a diamond cutter""s xe2x80x9crig,xe2x80x9d being no more than the bare essentials of a trough, a mallet, and a chisel. On the other hand, the dissection of a tooth may be accomplished by ultra-sonic means, the frequency and intensity of the ultra-sonic splitter being calculated to cause a disrupting resonation in the hard tooth exterior (and fragments) without undue damage to the pulp or soft cells within the tooth. Most embodiments of the apparatus of the present invention also provide, in the means for advancing the bit toward the trough, a restriction means by which the advance of the bit toward the trough may be controlled, so that the bit does not advance so far as to allow it to crush the tooth, or crush the pulp within the tooth, or crush hard tooth fragments against or into the pulp. However, in the mallet and chisel of the diamond cutter""s rig, and in other simple arrangements, the restriction means may be absent, and in such embodiments the risk of damage to pulp and cells within a tooth is increased.
After dissection of a tooth, some of the dental pulp from within may fall away from the hard tooth fragments. In such cases gathering the pulp for later use is easily accomplished. However, after most tooth dissections, much of the dental pulp within the tooth remains attached to hard tooth fragments. A second vessel may be used for removal of the pulp after the tooth is dissected. Such a second vessel may be a simple bath of isotonic solution, fitted with a pulp removal means. Such pulp removal means may be as simple as a tweezer, by which hard fragments may be removed from the pulp, or a burred shaft known as a barbed broach, by which the pulp may be drawn from the tooth fragments. However, a convenient arrangement for separating tooth fragments and pulp consist of a sharp or barbed projection situated on a sloping side of the second vessel, upon which the dissected tooth may be worked. In so working, the user would present a hard tooth fragment having pulp to the projection so as to catch the pulp on the projection. The user thereafter may pull the hard tooth fragment away from the projection, leaving the pulp on the projection or allowing it to fall off the projection and toward the bottom of the second vessel. Pulp remaining on the projection may be brushed off, or a separate means may be used to disengage the pulp from the projection, so that pulp remaining on the projection after working the hard tooth fragment against the projection also may fall off the projection and toward the bottom of the second vessel. Proceeding from a first tooth fragment to a second tooth fragment, if necessary, and so on to other tooth fragments, a user may conveniently pull virtually all pulp from the hard tooth fragments of a single donor. The sides of the second vessel may be sloped sufficiently to allow the pulp to fall toward the center of the second vessel, which may be fitted with a pit, for receiving a screen, and a screen with handle for formed to fit within the pit. Once the pulp from a donor falls into the center of the second vessel and into the screen, the screen may then be used to transport the pulp to another vial containing anti-coagulant, such as EDTA, heparin, or other anticoagulant, to retard coagulation, and to mix the pulp with appropriate chemicals for freezing in liquid nitrogen. The pulp may then also be transported to other locations for further manipulation and use using the screen of the second vessel or other means.
Utilizing the method of the present invention to identify teeth as the source of dental pulp from which Useful Cells may be Harvested, and thereafter isolated, expanded via cellular division, and used for medical and research purposes. Prior to the present invention no method is know for such identification and Harvesting of dental pulp from dentition of a patient or other donor, in order to use the pulp so secured, and the stem cells and other cells contained in the pulp, for beneficial medical purposes. Further no method allows extraction of pulp from within extracted while preserving a sterile environment to avoid contamination of the pulp, and trauma and infection of the donor. Utilizing the apparatus of the present invention, a user may employ such apparatus to practice the method of the present invention to advantage conveniently, and without such contamination, trauma, and infection. It may therefore be appreciated that the present invention holds advantages not found in any other existing methods or apparatus of the prior art, as the invention is specific to Harvesting of Useful Cells from an organ of the body which may be, and often is, discarded during childhood or routine dental work, and so carries with it the advantages related to Harvesting from such xe2x80x9cexpendablexe2x80x9d organ.
A principal object of the present invention is to identify human and other mammalian teeth as organs of the body from which Useful Cells may be Harvested, as an alternate source of cellular material to be used in therapeutic treatment and research, and provide a method and apparatus for Harvesting teeth for such purposes.
A further principal object of the present invention is to identify Useful Cells from teeth as cellular material which may be Harvested and expanded, and used medically for treatment of disease, tissue regeneration, and tissue replacement, and provide a method and apparatus for Harvesting teeth for such purpose.
A further object of the present invention is to provide a method and apparatus for Harvesting Useful Cells from organs of the body which avoids trauma and long recovery of the donor of such cells.
A further object of the present invention is to provide a method and apparatus for Harvesting Useful Cells from the body in such fashion as to promote a sterile field during such Harvesting.
A further object of the present invention is to provide a method and apparatus for Harvesting Useful Cells from the body while avoiding contamination and degradation of the cellular material obtained in such Harvesting.
A further object of the present invention is to provide a method and apparatus for Harvesting Useful Cells from the body while avoiding medical risks, including risk of infection of the donor in the Harvest, risk of infection of a patient by contamination of cells Harvested from the donor, and other problems associated with extracting marrow from other parts of the body.
A further object of the present invention is to provide a method and apparatus for Harvesting Useful Cells from the body having the unique characteristic of being preserved against contamination and degradation within the sealed environment of the hard tooth exterior, and to preserve such characteristic throughout processing, to result in uniquely viable medically useful cells, and unique products arising therefrom.
A further object of the present invention is to provide a method and apparatus for Harvesting Useful Cells from a patient before the need arises for such cells, so that Useful Cells may be treated and manipulated to produce cells of a kind, and in an amount, useable for treatment of that patient.
A further object of the present invention is to provide a method and apparatus for Harvesting Useful Cells from a patient before the need arises for such cells, so that Useful Cells may be treated and manipulated to produce cells useable for treatment of that patient which have not been affected by medical treatments normally destructive to the cells and tissues of that patient.
A further object of the present invention is to provide a method and apparatus for Harvesting Useful Cells from a donor which may be treated and manipulated to produce cells of a kind, and in an amount, useable for treatment of a patient other than the donor.

Stem cell and dental pulp harvesting method and apparatus


A load carrier for aligning a load of an aircraft is provided. The load carrier includes a carrier unit for mounting the load carrier on the aircraft, a load unit for mounting the load and a bearing unit for pivoting the load unit with respect to the carrier unit. The bearing unit has at least one curved rail element and at least one car element, which is displaceable along the rail element.

The inclination of a helicopter about its transverse axis may vary greatly during the different phases of flight (hovering, climbing, cruising, etc.) due to the design. As a result, an exterior load attached to the helicopter develops an unfavorable aerodynamic characteristic.
In particular, for stable forward flight, helicopters tilt the rotor plane forward to tilt the thrust vector of the main rotor in the direction of flight. This tilting of the rotor plane may lead to tilting of the entire helicopter about the transverse axis. Mounted exterior loads in this case also tilt about the transverse axis and then are exposed to oncoming cross-flow by the surrounding air in an unfavorable manner. It may therefore be advisable to align the exterior loads in accordance with the air flow. An electromechanical load carrier may therefore be used to align an exterior load about the transverse axis in the direction of flight of the helicopter.
Furthermore, when using weapon carriers as the exterior load, the load carrier is used as an aiming unit, which makes it possible to aim the weapon at the target independently of the position of the helicopter.
In this second application, an alignment of the exterior load by the load carrier (in this case a weapon carrier) may be used for aiming. The weapons, mounted as an exterior load, can be aligned with the target in this way, independently of movements of the helicopter.
For pivoting the exterior load, a trapezoidal guide for the exterior load may be used and can be driven by a linear actuator. Disadvantages of this arrangement may include the relatively large forces acting on the actuator because the effective lever of the center of gravity can be displaced significantly by adjusting the kinematics. Another disadvantage may be the space required for the rod of a trapezoidal guide.


Embodiments of the present invention provide a communication system, comprising: a first wireless network including a coordinator and a plurality of network devices associated with the coordinator; a second wireless network; wherein the first coordinator is arranged to notify at least one network device of the availability of data; and the at least one network device notified of the availability of data is arranged to associate with the second wireless network and to receive the data.

The present invention relates to a data communication system and communication method. In particular, although not exclusively, the present invention relates to a communications system and method which may communicate data to a large number of devices.
In some applications, a wireless network is required which supports a large number of devices, allowing data to be communicated amongst those devices with low latency. It is also desired that network devices have low power consumption, thus enabling network devices to be battery powered with minimal maintenance requirements.
For example, electronic shelf edge labelling (ESL) relates to the provision of information in a retail environment using electronic display devices. In a typical ESL system, electronic display devices are mounted upon shelves to display information, such as price information, to customers. Systems such as ESL systems have a number of requirements: they should support large numbers of devices e.g. in excess of 30,000 display devices; they should not require extensive infrastructure to be installed to support shelf-edge devices e.g. power and data cabling; display devices should require minimal maintenance; and the system should have low update latency.
It is an object of embodiments of the invention to at least mitigate one or more of the problems of the prior art.

Wireless data communication system and method


The disclosure teaches design features that can be used alone or in combination to facilitate faster, more uniform flow of glass through the apparatus and allows the thickness of the sheet to be adjusted. An overflow device is provided at the far end of the trough and is used in conjunction with tilting of the apparatus to expand the range of glass flow rate and glass viscosity for which this invention will produce satisfactory product. The forming apparatus can be made with non-linear weirs and the trough bottom to provide a greater range of flow rates. The glass flow in the inflow pipe can modulated or a contoured trough cross-section used to provide more uniform time dependent flow for forming the sheet. The forming apparatus can include an orifice on top of the trough and glass can be moved through the apparatus using pressure. Additional orifices can be provided on the bottom or sides to allow greater variability in sheet thickness. Irregularities in the thickness of the formed glass sheet may corrected by selective heating of the glass in the trough, heating the weirs or orifice, and selective heating of the glass flowing down the outside of the apparatus. A flow control plug can be inserted into the trough, such that flow dynamics can be altered during hot operation by insertion, removal or position adjustment of the flow control plug.

1. Field of the Invention
The invention pertains generally to the manufacture of glass sheet, and, more particularly to glass sheet formed from an overflow process.
2. Description of Related Art
This invention relates to the manufacture of glass sheet that is currently used for the production of TFT/LCD display devices that are widely used for computers now and are expected to be used for television sets in the future.
The glass that is used for these semiconductor powered display applications must have very high surface quality to allow the successful application of semiconductor type material. Sheet glass made using the apparatus of U.S. Pat. No. 3,338,696, incorporated herein by reference, makes the highest quality glass as formed and does not require post-processing. The patent teaches a manufacturing process termed: xe2x80x9cthe overflow processxe2x80x9d. The key feature of the overflow process is that the glass moves through the glass forming equipment and the untouched, xe2x80x9cvirgin glassxe2x80x9d, overflows and becomes the outside surface of the glass. Glass made using other processes requires grinding and/or polishing and thus does not have as fine a surface finish.
The teachings of U.S. Pat. No. 3,338,696 are still the state of the art as practiced today, however, the apparatus has limitations.
A major drawback of the present overflow process is the limited range of production rates that can be accommodated by a given apparatus. Simple mathematics teaches that the mathematical product of glass flow, glass viscosity, and the tangent of the tilt angle must be a constant to make glass of uniform thickness for a given apparatus. In practice the angle of tilt has practical limitations and the simple mathematical assumptions fail because of non-linearity, thus the limited range of production rate.
There is also no adjustment provision for curvature or other non-uniformity in the thickness of the glass sheet. During a manufacturing campaign the forming apparatus is subject to changes in shape caused by material erosion and by thermal creep of the material from which the apparatus is constructed. This produces non-uniform sheet thickness for which there is no corrective adjustment.
In practice, glass forming processes are intended to be run for years if possible. Stopping the line may take a month and re-starting another month. The whole system is run at extreme temperature, so the materials used are under constant stress and often wear or need to be adjusted. Stopping the production to make these adjustments or repairs is a highly undesirable option.
The apparatus of xe2x80x9cThe Overflow Processxe2x80x9d makes excellent glass during stable operating conditions, but it recovers from transient conditions very slowly. This is because the flow of glass through the forming apparatus is quite non-uniform. The glass that flows into the apparatus and forms the inflow end of the sheet has a different time history than the glass forming the far end of the sheet. Because the glass flow is from one end to the other, on the order of 10 percent of the glass on the far end of the sheet is at least one hour older than the equivalent glass on the near end. An additional time differential is caused by the rectangular cross-section of the trough which has regions of glass where the flow velocity is very slow.
Another drawback of the apparatus shown in U.S. Pat. No. 3,338,696 is that its physical size becomes larger as production rate is increased. Apparatus durability often requires that parts of the device are made from or coated with refractory metal, i.e. platinum. Thus increasing the size of the system substantially raises the cost of the manufacturing apparatus. The weir overflow process apparatus becomes large as production rates increase because the flow of glass in the trough, channeling glass to the overflow weirs, relies on gravitational flow. As the glass flow rate increases, either the trough must be larger, the slope of the weirs steeper, or the glass viscosity lower to accommodate this increased glass flow. Therefore, the range of production rates that can be accommodated by a given size apparatus is limited.
Another drawback is that the apparatus can only make glass sheet of a fixed width.
The present invention includes design features that can be used alone or in combination to facilitate faster, more uniform flow of glass through the apparatus and allows the thickness of the sheet to be adjusted.
An overflow device is provided at the far end of the trough and is used in conjunction with tilting of the apparatus to expand the range of glass flow rate and glass viscosity for which this invention will produce satisfactory product. The overflow device may be used in conjunction with tilting of the apparatus, changes in glass flow rate, and changes in glass viscosity (temperature) to regulate the thickness profile of the sheet. In addition, the forming apparatus can be made with non-linear weirs to provide a greater range of flow rates.
The glass flow in the inflow pipe can be modulated to provide more uniform time dependent flow for forming the sheet. Similarly, a contoured trough cross-section is taught which can minimize the quiescent flow regions.
The forming apparatus can include an orifice on top of the trough and glass can be moved through the apparatus using pressure. The orifice is narrow at the inlet end and wider at the far end to accommodate for the loss in static pressure of the glass as it flows to that end.
A forming apparatus can be provided with additional orifices on the bottom or sides to allow greater variability in sheet thickness. Effectively, an additional orifice adds glass to the middle of the formed sheet.
Irregularities in the thickness of the formed glass sheet may be corrected by selective heating of the glass in the trough, heating the weirs or orifice. This requires selective heating of the glass flowing down the outside of the apparatus to restore temperature uniformity at the bottom of the apparatus where the sheet is formed.
A flow control plug can be inserted into the trough, such that flow dynamics can be altered during hot operation by insertion, removal or position adjustment of the flow control plug.

Overflow downdraw glass forming method and apparatus


A porous formed article which comprises an organic polymer resin and an inorganic ion absorbing material, and has communicating pores opening at an outer surface, wherein it has cavities in the interior of a fibril forming a communicating pore, at least a part of said cavities opens at the surface of the fibril, and the inorganic ion absorbing material is carried on the outer surface of said fibril and on the surface of inner cavities.

In recent years, environmental quality standards for phosphor, boron, arsenic and fluorine ions in drinking water, industrial water, industrial wastewater, sewerage treated water and environmental water have been stiffened because of issues in environmental pollution and eutrophication, and a technology for removing them has been demanded.
Phosphor is one of agents causative of the eutrophication, and regulations on a closed area of water have been stiffened. It is also an element which is feared exhausted, and the technology to recover the element from effluent and reuse it has been demanded.
Boron is an element essential for the growth of plant but is known to adversely affect the growth of the plant when an excessive amount is given. Boron is further pointed out to have a possibility of giving an influence on the health of a human body, particularly causing health problems such as the deterioration of a generative function, when being contained in drinking water.
Arsenic is contained in effluent in a non-ferrous metal smelting industry, heated effluent from a geothermal power plant, and underground water in a particular area. It has been known since olden times that arsenic has toxicity. Arsenic tends to accumulate in a living body, and has been considered to cause chronic poisoning, weight reduction, sensory disturbance, liver disturbance, skin deposition and skin cancer.
Fluorine is often contained in effluent discharged from a metal-smelting, glass and electronic material industry. It has been concerned that fluorine may give the influence on a human body, and it has been known that it causes chronic fluorine toxicosis such as mottled tooth, osteosclerosis and thyroid gland disorder, when excessively ingested.
In addition, it is feared that amounts of these emitted hazardous materials will increase with the development of civilization, and the technology for effectively removing them has been demanded.
As for a conventional technology for removing these hazardous materials, a material has been known which has a hydrated ferrite of Ti, Zr or Sn deposited in a three-dimensional network structure made from polyurethane and polyacrylic acid base resin with the use of a suitable binding material (see Patent Document 1). This publicly known adsorbent is a material having the hydrated ferrite deposited on the three-dimensional network structure with the use of the binding material, and accordingly has a defect that the original ion exchange capacity of an adsorption substrate is not sufficiently developed and an adsorption rate decreases, because the used binding material plugs fine pores existing on the surface of the hydrated ferrite which is the adsorption substrate. The adsorbent also has a problem of supporting few amounts of the adsorption substrate in unit volume thereon, because of having a large cavity. The adsorbent further has to be produced with a complicated method.
In addition, the adsorbent is known which makes a hydrated cerium oxide powder supported on a high molecular material (see Non Patent Document 1). The adsorbent is porous, but has a thin film called a skin layer existing on its surface, and according has a defect of decreasing a diffusion rate of a substance to be adsorbed such as phosphor and boron into an absorbing material.
In addition, Patent Document 2 discloses an absorbing material produced by preparing a porous formed article made from cellulose, and making an adsorption substrate formed of hydrated zirconium oxide supported thereon afterward with an impregnation method. The absorbing material has a low binding force of the adsorption substrate because of making the adsorption substrate supported afterward with the impregnation method, and accordingly has a defect that the adsorption substrate flows out while being repeatedly used. In addition, cellulose tends to swell in water, and accordingly has a problem that when the absorbing material is packed in a column and a liquid is passed through it, a formed body is compressed and increases a pressure loss. Furthermore, cellulose has a property of being decomposed by a living organism, so that the absorbing material has a problem of being unsuitable for treating water in which miscellaneous microorganisms coexist such as sewage water, in point of durability in repeated use.    Patent Document 1: JP-A-09-187646    Patent Document 2: JP-A-2002-38038    Non-Patent Document 1: Industry and Environment, September, 1999, pp. 81-85

Porous formed article and method for production thereof


An improved method of subtracting laser amplitude fluctuations from a desired signal in a multi-line laser system and a detection system having improved noise cancellation are provided. This invention reduces the noise contribution from laser amplitude fluctuations by matching the spectral dependence of the light seen at a monitor of the laser output to the spectral dependence of a desired signal. This spectral matching results in an improved correction of the laser power in a desired signal.

Multi-line lasers are commonly used in a variety of instruments including those used to optically detect and size particles down to ˜0.1 micron diameter. These instruments measure the light scattered from particles as they pass through the laser beam. Determination of the size of the particle is determined by the amount of scattered light that is detected. The noise floor in these instruments comes from light scattered by the background molecular gas in the particle-laser interaction region (background scattering noise) and is of two types: a fundamental noise from the photon statistics (shot noise) present even in a perfect laser and technical background scattering noise from an imperfect laser source (technical background scattering). The background scattering noise reduces the sensitivity of the instrument. Shot noise is not reducible. To improve sensitivity, methods are here described to reduce the noise from technical background scattering.
In the highest-sensitivity system, the only source of noise would be the shot noise. However, there are other sources of noise (technical background scattering) that result in lowered sensitivity and therefore, result in an increase in the size of the smallest detectable particle. One of these additional sources of noise comes from laser amplitude fluctuations. These fluctuations appear as technical background scattering on the molecular-scattered light signal above the shot noise limit. One method used to reduce the noise from laser amplitude fluctuations is to monitor the laser output to determine the fluctuations in the laser amplitude and subtract these fluctuations from the scattered light signal (or in general, any other desired signal). This type of direct subtraction, however, does not work as well as expected in a multi-line laser system. In a multi-line laser, several lasing components at different wavelengths ("lines") compete for the overall gain of the system. The relative circulating intensity of the lines can fluctuate appreciably. For example, it is possible for the overall intracavity power to remain constant (that is, the sum of the line strengths remains fixed) while the relative line strength changes. This becomes problematic when the laser output light undergoes spectral filtering, caused for example, by the use of an output optic with spectrally non-uniform transmission. If the spectral transmission of light at a monitor of laser amplitude fluctuations is different than the spectral transmission at a monitor of a desired signal, a subtraction of the laser amplitude fluctuations from the desired signal will lead to imperfect noise cancellation. This effect is not generally appreciated, yet is present in most multi-line laser systems, due to imperfect optical components.
Some methods described to reduce noise in a laser system have been described. U.S. Pat. No. 4,798,465 (Knollenberg, Jan. 17, 1989) and continuation-in-part U.S. Pat. No. 4,893,928 (Knollenberg, Jan. 16, 1990) describe a particle detection device having background noise reduction. The noise reduction is achieved by use of a plurality of linear detectors, where each detector senses a portion of the optical path. The signals from the detectors are parallel processed to reduce the effect of background molecular scattering. U.S. Pat. No. 6,061,132 (Girvin, May 9, 2000) describes a particle counter having a dual detector array, wherein a detector in one array is used for noise cancellation, a detector in the other array is used to detect the signal from a particle, and the signals are subtracted to reduce the noise. U.S. Pat. No. 5,467,189 (Kreikebaum, Nov. 14, 1995) describes a particle sensor which subtracts background scattering signals from particle signals. U.S. Pat. No. 5,121,988 (Biesener, Jun. 16, 1992) describes a particle detector having monitoring of laser output power and adjustment of the current supplied to the laser to compensate. U.S. Pat. No. 6,414,754 (Johnson, Jul. 2, 2002) describes use of an ionic coloring agent on portions of the instrument to absorb stray light.
None of the above methods describes a method to cancel the laser amplitude noise fluctuation component in a multi-line laser system. An improved method of canceling the laser amplitude noise fluctuation component from a desired signal in a multi-line laser system is needed.

Method for noise cancellation by spectral flattening of laser output in a multi-line-laser instrument


Embodiments of the present invention are directed to a system for assisting creation of messages, by automatically recommending data to be included therein. The system includes an application configured to accept a set of user inputs of a first classification to determine and provide a group of suggested data relevant to the set of user inputs of the first classification. The group of data is chosen from an evolving collection of data of a second classification. The user is able to select any or all from the group of suggested data to adopt as the user's own and/or to provide additional or different data, which are of the second classification. The user inputs and the user's selection(s) are values collected for use in subsequent determinations.

Users today are able to utilize applications that provide them with forms to complete for creating posts, such as job posts. These applications, however, provide only a single form for employers to fill out, regardless of the type of job it is. There are drawbacks to this prior art one-form-fits-all model. First, the prior art form is simply a generic form. It typically has a single field for an employer to describe details of a job. Since the job description field is a general field, which does not provide the employer with any guidance on how to complete the field, the employer may not know how to effectively describe the job, may inadvertently fail to describe certain details of the job that may be crucial to an employee when searching and applying for jobs, or both. Sometimes the failure to provide aspects of the job will result in the job posting being returned at a bottom of a search return list, if it is returned at all. For example, employers oftentimes forget to provide skills, even though these skills are used for matching prospective jobs with employees during a job search. If the employer fails to include a skill that an employee bases the search on, then the job post may not be returned as part of the search return list.
The present invention addresses at least these limitations in the prior art.

System for assisting creation of messages by automatically recommending data to be included therein


A multiple phase winding for an electromotive device comprised of individual phase windings. Each phase winding includes multiple layers of conductors and defines working length portions and interior and exterior end-turn portions, wherein at least one set of end-turn portions defines notches which cut across the height dimension of all the layers of conductors. The notches of different phases intermesh. This geometry promotes low electrical resistance within the phase windings and good conductive heat transfer between the multiple phase winding and the housing of the electromotive device, allowing higher power density from the device.

The present invention relates to electromotive devices including electromagnetically excited machines and permanent magnet synchronous machines (PMM""s). For clarity and simplicity, the term permanent magnet synchronous machine (PMM) is used throughout this specification, but it should be clearly understood that the term is intended to include electromotive devices in general, including electromagnetically excited machines.
The electromagnetic forces developed in a PMM result from the interaction of a permanent magnet field with a stator current. This interaction can be fundamentally represented by the relation:
F=k*B*K*S
Where:
F is the electromagnetic force
k is a proportionality constant depending on geometry,
B is the airgap flux density,
K is the armature surface current density, and
S is the airgap surface area.
In order to increase the power density of the PMM, it is necessary to increase the airgap flux density B or the armature surface current density K, or the airgap surface area S (however increasing the airgap surface area typically implies making a larger machine, which may well increase the power but not the power density of the device). The airgap flux density B is limited by the magnetic properties of the permanent magnets and the saturation properties of any flux-carrying components. The maximum current density K is ultimately limited by the conductor insulation temperature rating and the thermal demagnetization of the permanent magnets. These temperatures, in turn, depend on the machine""s inherent thermal characteristics and cooling mechanism. Most approaches to increasing power density use aggressive cooling methods to allow more current for a given temperature rise.
The present invention provides for electromotive device designs incorporating multiple phase windings, each winding including one or more notched ribbon conductors, which results in higher power density devices than those available in the prior art. The designs improve the performance of the parameters affecting the electromagnetic force generated by the device, especially the armature surface current density xe2x80x9cOKxe2x80x9d, and to some extent the airgap surface area S.
The notched ribbon conductors of the present invention may be utilized in axial gap machines, in radial gap machines, or in linear actuators, and may be applied to both coil and wave windings. The conductors may use a standard ribbon having a constant thickness and height, or they may use custom-shaped ribbon conductors which have variable thickness and/or variable height. In any event, the planar conductor or ribbon conductor has a thickness which is substantially less than the height (or width) of the conductor.
The windings of the present invention are typically divided into three areas: the working area (or working length) where the conductor cuts across the magnetic field generated by the magnets, the interior end-turn area, and the exterior end-turn area. The end-turns connect two working lengths of the winding, and they are typically also divided into two areas: the cross-over areas (or cross-over lengths, of which there are typically two at each end-turn and which include the area where two phase windings cross over each other), and the bridging area (or bridging length). The cross-over lengths may be further subdivided into transition lengths which flank the actual cross-over or intermesh area itself and thus provide a transition piece between the working length and the intermesh area, and between the intermesh area and the bridging length. Notches cut in the windings at the cross-over areas are cut so as to reduce the height dimension, at the notch area, of all the ribbon conductors comprising a winding.
The multiple phase windings of the present invention utilize ribbon conductors with notches in the phase cross-over areas instead of using wire conductors. This results in many advantages, including:
Lower electrical resistance: A ribbon winding has a higher copper fraction (i.e. % of copper, as opposed to insulation and air, which fills a slot area), with fractions of 90% or more possible in contrast to copper fractions in the 60% range for round wire windings. The windings of the present invention have notched crossover areas (areas where one phase winding crosses over another phase winding), and these notches increase the resistance to the flow of electricity. Thus, it is counter-intuitive to use notches in the cross-over areas. However, the use of these notches, as compared to bending of the windings past each other, results in a substantial reduction in the required length of the end-turns of the windings, and this reduction in end-turn length more than compensates for the increase in electrical resistance due to the notches. Note that the end-turn areas are typically, but not necessarily, non-work-producing areas of the windings, so reducing the length of these end-turns areas improves performance of the device by reducing the overall thermal and electrical resistances and by allowing a smaller device for a higher power density.
Lower thermal resistance: Thermal resistance is a property relating the temperature rise in the winding to its heat conduction (or heat flow). It is a measure of how difficult it is for heat to flow out of the winding. With single stator, dual rotor, axial gap PMM""s, heat generated by the windings primarily flows out through the exterior end-turn/housing interface. The high copper fraction of the ribbon windings of the present invention (almost equivalent to solid copper) allows heat to flow easily along the length of the winding to the end-turns, which are clamped to the PMM""s housing, which acts as a heat sink to cool the windings. Furthermore, the notched cross-over areas allow both axially oriented faces of the end-turns to contact the housing in the xe2x80x9cbridgingxe2x80x9d length of the end-turns, thereby increasing the thermal contact area for more effective cooling, since both end-turn faces are available for heat transfer.
Greater Magnetic Airgap area: The use of notches resulting in planar stator faces often allows the magnetic airgap surface area S to be increased by extending partially over the end turn areas, where the conductors are transitioning from radial to tangential orientations, but still have a significant radial component which can contribute to torque production.
More Compact Structure: The use of notches allows the radial height of the end-turns (as well as lengths) to be shorter for a more compact winding structure. This, in turn, allows smaller machines with greater power density to be constructed.
Another benefit of this PMM design is that the actuator housing can be totally enclosed with minimal impact of cooling performance (since cooling primarily occurs by end-turn conduction, not internal convection of the windings).

Electromotive devices using notched ribbon windings


Described herein are systems and methods for ensuring plasma homogeneity in a discharge cell. The discharge cell may include a first hollow electrode and a second hollow electrode spaced away from the first electrode to define a discharge gap therebetween. A fluid inlet port may in fluid communication with an internal bore of the first electrode. A fluid outlet port may be in fluid communication with the discharge gap. A first pair of viewports may define a first optic pathway through the discharge gap. A second pair of viewports may define a second optic pathway through the discharge gap. A third pair of viewports may define a third optic pathway through the discharge gap, the third optic pathway defined through the hollow interior of the first and second electrodes.

Discharge cells provide reference sources of gas/plasma excitation and can be utilized as diagnostic and/or calibration devices for many applications. Some designs, however, may not permit homogeneous plasma production with controllable and repeatable parameters. Thus, a need in the art exists for discharge cell systems and methods that provide a homogeneous, strongly excited, low-temperature, non-equilibrium plasma with controllable and repeatable parameters.
Embodiments of the present invention and their advantages are best understood by referring to the detailed description that follows. It should be appreciated that like reference numerals are used to identify like elements illustrated in one or more of the figures.


An improved semiconductor device adapted to be metallurgically bonded to a substrate is disclosed. In particular, monolithic microwave integrated circuit (MMIC) device (10) includes a semiconductor wafer (12) having first and second major surfaces and defining at least one via (34) extending therethrough. An electrical circuit is disposed on the first surface of semiconductor wafer (12). In accordance with this invention, MMIC device (10) includes a ground-plane metallization system (32) provided on the second surface of the semiconductor wafer (12). Backside metallization system (32) promotes preferential "de-wetting" of solder within vias (34) to reduce solder failures associated with die-attach processing. Backside metallization systems (32) includes a ground-plane layer (36) and a second layer (38) fabricated from a non-wettable material which is deposited within via (34). Third layer (42) is deposited on second layer (36) but terminates adjacent a peripheral edge of via (34). Third layer (42) promotes wetting outside via (34) during solder die-attach processing.

1. Field of the Invention
This invention relates to semiconductor devices, and more particularly to monolithic microwave integrated circuit (MMIC) designs for improved manufacturability.
2. Discussion
Advances in semiconductor device technology have recently included the improvement in design and manufacturability of integrated devices and systems. For instance, one type of integrated device that recently has received increased attention is monolithic microwave integrated circuits (MMIC) for application in radar detection systems. Radar systems are often used in conjunction with munition and obstacle detection sensor systems for sensing electromagnetic radiation in the microwave frequency band. Specifically, the development of radar for future military defense systems will incorporate the use of electronically steered antennas (ESA) that offer improved beam agility, higher power and increased target range. The ESAs are comprised of an array of passive and active integrated circuits that transmit and receive the electronic radar signals. The transmit/receive (T/R) modules include microwave integrated circuits that are used by the thousands for each radar system and are a significant cost driver in the production of an affordable radar system.
In general, microwave integrated circuit devices are semiconductor devices fabricated by combining one or more semiconductor layers. Of the several conventional methods known, one method of fabricating microwave integrated circuits is to form a junction that includes a transition from a n-type (electron conduction) to a p-type (hole conduction) region. Typically, this can be accomplished by one or more methods such as formation of a junction by diffusion of dopants, ion implantation of dopants, or the growth of contiguous n-type and p-type layers. These methods, however, generally require the use of complex equipment and extensive processing steps. It follows then that the fabrication of typical microwave integrated circuit devices can be relatively expensive.
An alternative and relatively more simple junction formation technique involves forming a Schottky barrier, whereby a metal is deposited on a semiconductor layer. Because of some potentially adverse metal-semiconductor reactions, and sensitivities to surface conditions and small voltage steps obtainable particularly with n-type materials, the yield and quality of these devices has, until recently, been impractical for many microwave applications.
In recent years, advances in MMIC design technology, including the use of gallium arsenide (GaAs) as a semiconductor, have limited the use of conventional automated equipment in microwave circuit assembly facilities. Microwave circuit assembly is considered to be very complex because gallium arsenide integrated circuits are significantly smaller and more delicate than conventional silicon integrated circuits. It is believed that no automated high volume fabrication or assembly facility currently exists for gallium arsenide integrated circuits. However, despite the manufacturability disadvantages of selecting gallium arsenide in lieu of silicon or other materials as the semiconductor substrate, numerous advantages are also apparent. The major advantage being the gallium arsenide integrated circuits have faster switching speeds of logic gates and significantly lower parasitic capacitance to ground.
The mechanical properties of gallium arsenide are well below that of silicon in hardness, fracture toughness and Young's modulus. Gallium arsenide is very brittle, about one-half as strong as silicon. This means that a much greater degree of process control is mandated to ensure reliability and repeatability necessary to cost-effectively produce gallium arsenide MMIC.
Additionally, gallium arsenide MMIC technology requires that the electrical grounding paths be very short. Therefore, gallium arsenide wafer thinning is employed to reduce the thickness of MMIC wafers to approximately 0.004" to 0.010" thick. In comparison, conventional integrated circuits have a semiconductor wafer thickness in the range of 0.015" to 0.030". Following the wafer thinning processing, a through-substrate via etching process is then performed to form a ground path directly through the chip to circuitry loaded on the top of the MMIC surface. The top surface of the MMIC has electrical conductors that delineate circuitry capable of operating at microwave frequencies. In many cases, these conductors are made into structures called air bridge crossovers. Typically, air bridges are located at the field effect transistors (FETs) and at various capacitors located on the MMIC surface. Routinely, the air bridge crossovers are densely packed in close proximity on the MMIC top surface. These air bridge crossovers can be easily damaged and as such are not accessible to conventional high rate circuit assembly techniques.
In general terms, die-attach is the process of bonding an integrated circuit chip to a substrate to produce an electrical interface therebetween. Commonly utilized substrates include printed wire boards (PWB), thin film gold metallized alumina and multilayer alumina header packages. Conventional bonding mediums include electrically conductive epoxies or solder alloys selected from metals of the type including indium, lead, tin, gold, silver, platinum, palladium or combinations thereof. Moreover, solder die-attach is the process of metallurgically bonding the integrated circuit chip to the substrate or readout device. The metallurgical bond provides an electrical interface between the components and acts to dissipate heat during thermal operational cycling. Vias extending through the semiconductor wafer provide an electrical communication path between circuitry disposed on the top surface of the MMIC and the substrate.
The present invention is directed to an improved ground plane metallization layer provided on the bottom surface of a integrated circuit chip, and more preferably a MMIC chip, for solder attachment to a substrate. Until recently it was believed that completely filling the vias of gallium arsenide MMICs with solder during die-attach was desirable because the solder "post" could dissipate a greater amount of heat from components electrically interfaced with the vias. However, it has been discovered that solder-filled chip vias cause reliability problems during operational temperature cycling. The thermal coefficients of expansion of the solder alloy, the gallium arsenide MMIC chip and commonly employed substrates are not matched sufficiently to inhibit cracks from forming at the vias and propagating through the MMIC chip. In fact, in some instances the solder completely penetrates the via and flows onto the top surface of the MMIC. Such undesirable failure modes generate excessive scrap which has made application of gallium arsenide MMICs impractical.
Another disadvantage of conventional solder die-attach processing includes the excessively manual method of positioning solder preforms in accurate alignment between a MMIC chip and a substrate prior to reflowing the solder. Inaccurate positioning produces non-uniform interface layers which results in reduced electrical performance.
Among the advantages of the present invention is that relatively efficient die-attach processing of semiconductor devices, including microwave integrated circuits, can be realized without specialized equipment or handling requirements. The improved MMIC design is relatively inexpensive and can be carried out successfully utilizing standard solder die-attach technology. The present devices exhibit improved reliability in operation and in manufacturability as compared to conventional integrated circuits. Therefore, it is an object of the present invention to provide an improved MMIC backside metallization system which will preferentially "de-wet" the solder at the solder-via interface or bond-line. Such preferential "de-wetting" substantially increases MMIC reliability by eliminating failure modes associated with via cracking.

Integrated circuit solder die-attach design and method