An object of the present invention is to provide a three-dimensional cell support that is capable of uniformly distributing cells and retaining the cells in a state without nonuniformity and is made of a biodegradable material. The present invention provides a cell support consisting of a porous body made of a biodegradable material, the porous body having the following properties:    (a) a porosity from 81% to 99.99%,    (b) an average pore size of 10 to 400 μm,    (c) having a hole interconnecting pores, and    (d) a water absorption rate from 1000% to 9900%.

The practical utilization of regenerative medicine, which helps the regeneration of living tissues/organs that have fallen into functional disorder or functional incompetence, is currently proceeding. The regenerative medicine is novel medical technology of re-creating the same or similar forms or functions as in original tissues using 3 factors, i.e., cells, scaffolds, and growth factors, for living tissues that no longer recover by only natural healing ability possessed by organisms. In recent years, treatments using cells have been being gradually realized. Examples thereof include cultured epidermis using autologous cells, cartilage treatment using autologous cartilage cells, bone regeneration treatment using mesenchymal stem cells, cardiac muscle cell sheet treatment using myoblasts, corneal regeneration treatment using corneal epithelial sheets, and nerve regeneration treatment. These novel treatments, unlike conventional alternative medicine based on artificial materials (bone prosthetic materials or hyaluronic acid injection), help the repair or regeneration of living tissues and therefore produce high therapeutic effects. In fact, products such as cultured epidermis or cultured cartilage using autologous cells have been launched.
However, the problem of the variability of therapeutic effects or the problem of unexpected adverse effect has been in concern and has arisen actually in the treatments using cells as described above. Leading causes of such problems are considered to be the heterogeneity of cells obtained in culture and the nonuniform engraftment of cells at transplantation sites.
For example, it is known that cartilage cells tend to be dedifferentiated during the course of culture, and therefore, a culture method keeping them in a constant state has been demanded. Moreover, it is known that a cell generally changes its state depending on conditions under which the cell is present, particularly, cell density. For example, it is known that mesenchymal stem cells (MSCs), which are currently expected to be applied to treatments, tend to be differentiated into fat cells under low cell density conditions and, on the contrary, differentiated into osteocytes under high cell density conditions. For other cells as well, a very important factor is to control cell density at a constant level.
Meanwhile, many reports have demonstrated that a three-dimensional culture technique is important for efficiently culturing cells under conditions closer to an in vivo environment. However, it is known that when cells are inoculated to a three-dimensional matrix, the cells are not uniformly distributed in the matrix and are disproportionately located in the matrix. For the three-dimensional culture, it is therefore difficult to keep cell density constant. Although the three-dimensional cell culture presumably depends on the physical, biological and chemical properties of matrices, such as the adhesiveness of matrices to cells, the structure of matrices, and the hydrophilicity and hydrophobicity of matrices, it is generally difficult to uniformly distribute cells in a three-dimensional matrix and keep cell density constant. As a result, the state in which a cell state is not uniform in the three-dimensional matrix is formed, resulting in problems associated with cell homogeneity.
Moreover, for transplantation treatment using the obtained cells, the transplantation of cells cultured, for example, as in the atelocollagen gel-embedding culture of cartilage cells, together with a matrix is performed, in addition to the injection of a cell suspension. In this case, after culture, a construct consisting of a three-dimensional matrix and cells is trimmed appropriately for the shape of a transplantation site and transplanted thereto. If the cells are nonuniformly distributed in the three-dimensional matrix, nonuniform cell distribution also occurs in a fragment for transplantation obtained by trimming, generating a site strongly exhibiting therapeutic effects and a site hardly exhibiting therapeutic effects. Furthermore, the nonuniform cell density causes nonuniformity in the physical properties and physical strength of the transplanted fragment. Such nonuniformity becomes a factor responsible for the variability of therapeutic effects and reduction in the survival rate of the transplanted fragment and results in a lack of expected therapeutic effects. Furthermore, for aptitude required for the three-dimensional matrix as described above, it is important to be made of a material having biocompatibility, desirably biodegradability (because of the need for being spontaneously degraded in vivo), because of its use in transplantation. Unfortunately, there has not existed a three-dimensional matrix that satisfies all of these requirements.
As described above, from the viewpoint of regenerative medicine using cells, it is required that the three-dimensional matrix should be capable of uniformly distributing cells and retaining the cells in a state without nonuniformity both in a culture step and in a transplantation step and be also made of a biodegradable material because of the need for being applied to transplantation. Previous porous polymers, three-dimensional collagen matrices, or collagen gel-embedding culture have hardly overcome such a problem.
In general, living tissues are composed of cells and extracellular matrices (polymer constructs). Various life phenomena are consequences of their complicated interactions. Cells release various growth factors (drugs) and influence their own functions or the functions of other cells. On the other hand, the extracellular matrices secreted from the cells provide hydration space for cell functions, function as drug depots or scaffolds, and have significant influence on the functional manifestation or differentiation of cells.
The regenerative medicine, which has made remarkable progress in recent years, is gathering a lot of attention as highly advanced medicine that may substitute for artificial organs or organ transplantation. For realizing the regenerative medicine, it is important to wield each of principal factors in the regenerative medicine, i.e., cells, culture apparatuses, growth factors (drugs), and cell scaffolds (artificial extracellular matrices and materials).
Bone regeneration in the orthopedic or dental field is known as a region that is gathering a lot of attention in the regenerative medicine field. Bone diseases affecting legs or lower backs cause inability to walk, while bone diseases affecting teeth make dietary intake difficult. Thus, a bone disease causes remarkable reduction in QOL.
Infuse (combination of BMP-2 with a collagen sponge) treating spinal cord injury as well as BioOss (deproteinized bovine bone powder) and Gem21 (PDGF and βTCP) as bone prosthetic materials regenerating alveolar bone are known as current typical preparations for bone regeneration treatment. In general, [1] strength for structural maintenance, [2] securing of space for bone regeneration, [3] scaffolds for cells to regenerate bone, [4] induction of differentiation and growth of cells to regenerate bone, and [5] degradability associated with bone regeneration are known as properties required for preparations for bone regeneration treatment. Collagen, βTCP, or the like is widely used as a scaffold material for the preparations for bone regeneration treatment. Moreover, at the research level, bone regeneration has been performed by impregnating a gelatin (denatured form of collagen) sponge with bFGF or BMP-2 (Journal of Neurosurgery 91 851-856, 1999). Furthermore, studies have also been made on bone regeneration treatment using a therapeutic agent obtained by involving bone marrow mesenchymal stem cells in a scaffold matrix and culturing it (Motohiro Hirose and Hajime Ogushi, "Regenerative Medicine of Bone Using Regenerated Cultured Bone Tissues", The Tissue Engineering 2007, 178-183; 2007.7).
The bone regeneration means that osteoblasts generate bone matrices to form hard bone consisting of osteocytes and the bone matrices, and is a phenomenon achieved by the osteoblasts. Not only the utilization of a cell graft (bone marrow mesenchymal stem cells, etc.) grown ex vivo but also the bone regenerating effect of growth factors (drugs) induces bone regeneration by the action on host-derived cells in a neighborhood thereof. For example, BMP differentiates undifferentiated mesenchymal cells into osteoblasts by its action and activates bone formation by the osteoblasts. Thus, since cells predominate in the bone regeneration, a scaffold material serving as a cell scaffold is very highly important.
Gelatin is well known as a typical scaffold material in general regenerative medicine. Gelatin is known as a material having high biocompatibility and high safety and has a good record with medical applications. Likewise, collagen is known as a material having a good record, but is lower soluble than gelatin and is largely limited by the concentration and pH of its solution (collagen cannot be prepared into a solution with a high concentration of dozens of %, a neutral solution, or the like). Hence, there are usually limitations on products into which collagen may be processed, prepared, or molded. Thus, a scaffold matrix using gelatin is desirable. However, there is a general perception that the gelatin matrix is less suitable as a scaffold material particularly for bone regeneration treatment. For example, it is disclosed that a gelatin sponge alone inhibits bone regeneration (Tabata, et al., Journal of Neurosurgery 91 851-856, 1999). Moreover, Ishii et al. (Dental Outlook, 97 (3), 665-677, 2001) have examined the influence of a collagen sponge and a gelatin sponge on the ability to regenerate alveolar bone and stated that gelatin lacks the ability to regenerate bone, compared with collagen.
In addition, since the bone regenerating power of a scaffold material alone is insufficient in case of collagen, ceramic materials, or synthetic polymers, their combinations with BMP, autologous blood, or autologous bone marrow mesenchymal stem cells have been reported under the present circumstances.
A cause of the absence of the favorable ability of these scaffold materials to regenerate bone has been considered to be insufficient "ability to infiltrate (introduce) cells into the scaffold matrix" or insufficient "ability to distribute or retain cells in the scaffold matrix". The present inventors have thought that the absence of sufficient cell introducing power, distribution, or retaining power of the scaffold matrix as a cell support is responsible for not leading to bone regeneration.
For example, JP Patent Publication (Kokai) No. 62-122586 A (1987) discloses a porous support having a porosity of 40 to 95%, desirably 60 to 80% or lower, which consists of polyester or polypropylene. The porous support with the porosity cannot uniformly distribute or retain cells. Alternatively, JP Patent Publication (Kokai) No. 8-89239 A (1996) discloses a porous collagen sponge. It is known that the collagen sponge cannot uniformly distribute cells in a three-dimensional manner, possibly depending on its hydrophobicity or due to the heterogeneity of the material, though this cause is not clear. In addition, in the case where cells are cultured in advance and then transplanted, there also exists an approach called gel-embedding culture in which cells are embedded in a collagen gel and cultured. However, the cells are disproportionately located in the gel and nonuniformly distributed.

Cell support and bone regeneration material


The present invention relates to a process for the preparation of esters of hydroxy tiglic aldehydes which are the key intermediates for Vitamin-A acetate synthesis and various perfumistic products, said process relates to the hydroformylation of biscarboxylic esters of but-2-ene-1,4-diol, followed by deacetoxylation of its hydroformylation compound, in the presence of heterogeneous catalyst having rhodium complex entrapped, anchored or teethered on the acidic support, said acidic support causes deacetoxylation in the reaction mixture immediately after hydroformylation, to give 100% selectivity to the carboxylic esters of hydroxyl tiglic aldehydes in a single step.

The carboxylic esters of γ-hydroxy tiglic aldehydes have attracted strong industrial interest, as they are known intermediates for vitamin-A and various perfumistic products. Various methods have been described in the prior art for the preparation of these esters. U.S. Pat. No. 3,760,004 by Freyschlag et al, discloses the preparation of these esters by halogenating a member of the group consisting of 2-formyl-2-hydroxybutene-3 and a di-lower alkyl acetal and a lower fatty acid acylate, with a halogenating agent selected from the group consisting of thionyl chloride, thionyl bromide and phosgene in the presence of a tertiary amine. This conventional process for the synthesis of the carboxylic esters of γ-hydroxy tiglic aldehyde suffers from the drawback of using harmful gases like phosgene, thionyl chloride or thionyl bromide. Bis-monocarboxylicacid esters of 3-formylbutane-1,2-diol have also been used as starting materials for the synthesis of the esters of γ-hydroxy tiglic aldehydes as disclosed in U.S. Pat. No. 3,732,287 by Himmmele et al. This patent describes a process where Bis-monocarboxylicacid esters of 3-formylbutanediol-1,2 are hydroformylated in the presence of carbonyl complex of rhodium at elevated temperatures and super atmospheric pressures. The pressure requirements are from 300-1000 atmospheres. The use of very high temperatures and pressures involves the use of expensive equipment and costly handling procedures to get the desired product. The use of such high pressures mitigates against the commercialization of this process. U.S. Pat. No. 4,124,619 by Fitton et al, discloses another method of synthesis, via the hydroformylation route, using biscarboxylic acid esters of but-2-ene-1,4-diols as the starting material to give carboxylic esters of γ-hydroxy tiglic aldehydes. In this patent biscarboxylic acid esters of but-2-ene-1,4-diols are converted to the compound of the formula 2 by treating with a mixture of carbon monoxide and hydrogen in the presence of a Rhodium catalyst. In a separate step the compound 2 is converted to compound 3 by pyrolysis in the presence of a strong organic or inorganic acid catalyst at a temperature of from 70° C. to 250° C. at atmospheric pressure or under vaccum of 1 mm Hg to 700 mm Hg. This patent describes the hydroformylation route using the homogeneous Rhodium catalyst system. The major disadvantage of this route is a great difficulty in separating the catalyst from the reaction mixture. Distillation has to be done to separate the products from the catalyst system. The catalyst is not stable after distillation at higher temperatures. And then deacetoxylation is done as a separate step, which requires the presence of strong acid catalysts or elevated temperatures.
The conventional processes for the synthesis of carboxylic esters of γ-hydroxy tiglic aldehydes suffer from many drawbacks. The earliest procedures by conventional routes require the use of harmful halogenating gases (U.S. Pat. No. 3,760,004). The later processes using the oxo reaction proved to be non-economical because of the very high-pressure requirements (U.S. Pat. No. 3,732,287). Another process using the hydroformylation route at comparatively lower pressure conditions uses the Rhodium catalyst system in the homogeneous reaction conditions, and so there is a difficulty in separating the catalyst from the reaction mixture and there is a loss in the amount of product upon distillation (U.S. Pat. No. 4,124,619). And deacetoxylation to get the required carboxylic esters of γ-hydroxy tiglic aldehydes is a two-step process.
There is a commercial interest in carboxylic esters of γ-hydroxy tiglic aldehydes, as they are well known intermediates for vitamin-A and various perfumery applications. An increasing academic as well as industrial attention has been paid towards research in developing new methods for the higher selectivity of carboxylic esters of γ-hydroxy tiglic aldehydes and easy catalyst separation from the reaction mixture. In view of the advantages and the features of the present invention, this improved process, would be a significant advance in the current state of art related to the synthesis of carboxylic esters of γ-hydroxy tiglic aldehydes by the hydroformylation route, having easy catalyst separation and a 100% selectivity towards carboxylic esters of γ-hydroxy tiglic aldehydes in a single step.

Process for preparation of esters of hydroxy tiglic Aldehydes

Council of Scientific & Industriual Research


N-Substituted sulfoximines are effective at controlling insects resistant to common insecticides.

The present invention concerns a novel method to control certain insect pests, specifically those that have developed resistance to one or more classes of insecticides, through the use of N-substituted sulfoximines.
The development of resistance to insecticides in insect populations is a well recognized phenomenon and there are well documented cases of resistance for all of the major classes of insecticides (Georghiou and Saito, 1984 Pest Resistance to Pesticides. Plenum Press, New York; Whalon et al., 2007 Arthropod Pest Resistance Database, http://www.cips.msu.edu/resistance.rmdb). The reduction in effectiveness of insecticides due to the development of resistance is one of the forces that drives the discovery and development of new insecticides.
Predicting whether or not a resistance mechanism that has conferred resistance to an existing insecticide will confer resistance to a novel insecticide (i.e., cross-resistance) is not necessarily a simple matter. In the case where resistance is conferred by a change or modification in the molecular target at which the insecticide acts (i.e., target-site resistance), a novel insecticide that acts at a different target site is unlikely to be affected by the resistance mechanism. Thus, in such a case in which the target site at which a novel chemistry acts is known and the resistance mechanism of concern involves a modification to a different target site, one could predict with some confidence that the resistance mechanism would not confer resistance to the novel chemistry.
In contrast to the above, the case where the target site of the novel chemistry is not known or where resistance is conferred by some mechanism other than target site insensitivity (e.g., metabolic detoxification, sequestration, or excretion), cross resistance is difficult to predict. In these cases, empirical assessment of the cross-resistance among insecticide chemistries using well characterized resistant populations or "strains" of a target pest species provides the most direct and compelling evidence for the likelihood of cross-resistance
One of the newer and more successful classes of insecticides to be introduced in past 25 years is the neonicotinoids. The introduction of neonicotinoid insecticides has provided growers with invaluable new tools for managing some of the world's most destructive crop pests, including species with a long history of developing resistance to earlier-used products. Imidacloprid was the first major active ingredient of the neonicotinoid class to reach the market. Research on molecules with a similar structure containing the 6-chloro-3-pyridylmethyl moiety led to acetamiprid, nitenpyram and thiacloprid. The substitution of the chloropyridinyl moiety by a chlorothiazolyl group resulted in a second subgroup of neonicotinoid insecticides including clothianidin and thiamethoxam.
Although the neonicotinoids have proved relatively resilient to the development of resistance, high levels of resistance have been documented in field-collected populations of the whitefly, Bemisia tabaci. During the late 1990s, resistant species increased in potency with more recently-collected strains of this whitefly exhibiting more than 100-fold resistance to imidacloprid, and comparable levels of resistance to thiamethoxam and acetamiprid (Elbert and Nauen, 2000 Pest Manag Sci. 56: 60-64; Rauch and Nauen, 2003 Arch Insects Biochem Physiol. 54: 165-176; Gorman et al., 2003 Proc BCPC Intl Cong: Crop Science & Technology. 2: 783-788). The major mechanism of resistance in whitefly to neonicotinoid insecticides appears to be an elevated detoxification capability (Rauch and Nauen, 2003 Arch Insects Biochem Physiol. 54: 165-176) and no target-site resistance has been found in neonicotinoid-resistant whitefly populations (Nauen and Denholm, 2005 Arch Insect Biochem Physiol. 58:200-215).
Neonicotinoid insecticides remain valuable and effective tools for the management of insect pests in most areas in spite of the limited development of resistance. Control of neonicotinoid-resistant insect pest populations, or for that matter other insecticide-resistant insect pest populations, will rely on the availability of insecticides that are effective on the resistant populations. Preventing or delaying the development of insecticide-resistant insect pest populations also relies on the rotation of insecticides that are not affected by the same resistance mechanisms. In either case, new insecticides that lack cross-resistance to currently available insecticides are imminently needed.

Method to control insects resistant to common insecticides


A frequency synthesizer comprises a single phase-locked loop controlled by a reference clock formed by a voltage-controlled oscillator, a programmable divider with variable division rank M, a phase detector, and a loop filter. It also comprises a predetermined number n of fractional division structures, each implementing a frequency step P.sub.i.times.F.sub.reF lower than the reference frequency F.sub.ref. Each fractional structure is coupled in parallel with said programmable divider to add to said division rank M fractional increments P.sub.i such that the ratio between the frequency F.sub.vco provided by said oscillator and said reference frequency be defined as a function of said increments P.sub.i by the relationship: ##EQU1##

The present invention relates to a frequency synthesizer with a phase-locked loop with multiple fractional division.
A frequency synthesizer with a phase-locked loop comprises conventionally in the manner described, for example, in the book of U. L. Rhode entitled "Digital PLL frequency Synthesizers--Theory and Design", 1983, Prentice Hall Inc. Englewoods Cliffs, a voltage-controlled oscillator, a variable-modulo divider, a phase detector, clock providing a reference frequency F.sub.ref, and possibly a loop filter. When the loop is locked, if M denotes the value set for the divider, the output frequency F.sub.vco from the voltage-controlled oscillator is equal to M times the value of the reference frequency F.sub.ref. When the value M set for the divider changes, the synthesized frequencies obtained change by steps equal to the reference frequency F.sub.ref, within the operating limits of the voltage-controlled oscillator.
To obtain a frequency synthesis step lower than F.sub.ref, it is known to introduce a fractional division loop which produces a frequency increment equal to a/Q times the reference frequency F.sub.ref, where Q is equal to the quotient of the reference frequency by the desired frequency step, where 0.ltoreq.a.ltoreq.Q-1.
Through a digital phase accumulator system, the main division ratio M is incremented by one unit for every occurrence of Q cycles of the reference frequency. The frequency step is then equal to the reference frequency divided by Q.
The advantage of this approach is that for comparable characteristics, the number of steps M to be set for the divider is reduced and that the loop filter has a higher cutoff frequency, which improves the response of the loop.
However, while the foregoing device is well suited to frequency synthesis, it is not appropriate for the synthesizers modulated in frequency or in phase from a modulation introduced, for example, in the reference frequency, for it appears that the maximum rate of this modulation is limited to low values. In addition, the synthesis frequency lines which appear at the output of the voltage-controlled oscillator and which are mainly due to the phase jitter of the phase comparator have relatively high levels which give to these synthesizers a relatively poor spectral purity.
However, when using not a single fractional division structure, but two of them, as is described in the French patent application NO 2 426 358 entitled "Synthetiseur de frequence a division directe a pas apres virgule", it is possible to improve in a very significant manner the spectral purity of the signals from the synthesizers with fractional division.
However, for some applications, this improvement is not sufficient, in particular it does not allow to use such synthesizers in communications systems with fast frequency agility.

Frequency synthesizer with a phase-locked loop with multiple fractional division


The present invention relates to a multi-antenna radio channel measurement system and method which generates a Time Division Duplex (TDD) timing signal and measures a two-way radio channel. The multi-antenna radio channel measurement system which measures a probing signal for measuring a radio channel, the multi-antenna radio channel measurement system including: a baseband unit alternately transmits the probing signal for measurement and receives the received channel signal to be measured based on a TDD synchronization time; a synchronization unit which obtains time synchronization with the other radio channel measurement system, generates a transmission/reception synchronization signal, and provides the transmission/reception synchronization signal to the baseband unit; a transceiver unit which up converts the probing signal for measurement and down converts the received channel signal; and a radio frequency (RF) front-end unit which switches suitable antennas according to a timing control signal of the baseband unit.

A next-generation mobile communication system requires a technology providing a high-speed data transmission rate to improve a voice service and low-speed data service in a conventional art and provide a variety of high-speed multimedia services. Various technologies such as broadband frequency use and a method using a multiple antenna have been conducted to achieve a high-speed data transmission rate. A system using a multiple antenna is sensitive to features of radio channel in comparison with a single-antenna system in a conventional art. Accordingly, when designing a multi-antenna system, features of radio channel are required to be accurately ascertained. A next-generation radio communication system using the above-described multi-antenna is expected to be generally used in a city where electric waves are affected by buildings, trees, and the like. Also, a next-generation radio communication system using the above-described multi-antenna is expected to be widely used for wireless high-speed data communication.
In general, a multi-antenna radio channel measurement system, referred to as a channel sounder in a conventional art, is one-way measurement system, and is divided into a transmission system and a receiving system. A one-way channel sounder in a conventional art measures a radio channel in a city or an area where traffic is complex such as an urban macro or urban micro, while moving according to a specific route using a moving vehicle. In this instance, to measure a radio channel, multi-antennas for transmission and transmission system are installed in a base station or steel tower relatively higher than surrounding buildings, and multi-antennas for receiving and receiving system are installed in the moving vehicle. Through the measurement method described above, a radio channel emitted in a base station, that is, a change of downlink radio channel in various environments according to a route of a moving vehicle is measured. As opposed to the configuration above, a receiving system and multi-antennas for receiving may be installed in a base station, and a transmission system and multi-antennas for transmission may be installed in a moving vehicle. Through this, a moving vehicle emits an electric wave for measurement while moving based on a specific route, and a base station collects measurement data of an uplink radio channel emitted by a moving vehicle.
However, a one-way radio channel measurement system and method of operating the same in a conventional art is required to sequentially operate a downlink and uplink in order to measure a number of routes in a same measurement area and in a variety of environments. For this, a measurement apparatus and antenna are required to be installed in a base station and moving vehicle, respectively, and a downlink measurement is to be performed. After the downlink measurement is complete, the measurement apparatus and antenna of each of the base station and moving vehicle are changed and installed, and an uplink measurement is to be performed. A single measurement path in the same area and environment is measured twice in the system and method described above, which is inefficient and time-consuming, increases costs and wastes human resources.
Also, features of radio channel to be measured frequently change depending on an environment. In particular, a speed of moving vehicle when measuring an uplink is not identical to a speed of moving vehicle when measuring a downlink, and thus these channels may not be measured in the same environment. Also, radio channel measurement data of each of the uplink and downlink measured as described above is not measured at the same time, same measurement point, and surrounding environment, although the same path is measured. Accordingly, collected channel data to estimate correlation between data of each of the uplink and downlink may not be accurate.
Thus, a two-way radio channel measurement system is established, and a method and system to simultaneously measure an uplink and downlink in a same environment and condition when measuring a radio channel is required. Also, a technical control method and operation method to embody the two-way radio channel measurement system is required.

Multi-antenna radio channel measurement system and method which generates time division duplex timing signal and measures two-way radio channel

Electronics and Telecommunications Research Institute


A surface acoustic wave device includes an electrode and a dielectric layer laminated on a piezoelectric substrate, in which the electrode includes a first electrode film containing Pt, Au, Ag, or Cu and a second electrode film containing Al, the normalized film thickness h/λ of the first electrode film is about 0.005 or more and at most about 0.015 in the case of Pt, the normalized film thickness h/λ of the Al film is about 0.06 or more and at most about 0.185, and the normalized film thickness h/λ of the dielectric layer is about 0.2 or less.

1. Field of the Invention
The present invention relates to a surface acoustic wave device for use in a resonator, a band-pass filter, or other suitable component. More specifically, the present invention relates to a surface acoustic wave device in which an IDT electrode and a dielectric film are disposed on a piezoelectric substrate.
2. Description of the Related Art
Surface acoustic wave devices have been widely used as a resonator or a band-pass filter of communication apparatuses heretofore.
For example, the following Japanese Unexamined Patent Application Publication No. 2008-522514 discloses a surface acoustic wave device in which an IDT electrode and a dielectric film containing SiO2 are laminated on a piezoelectric substrate. Japanese Unexamined Patent Application Publication No. 2008-522514 discloses that the temperature characteristics can be improved by forming the SiO2 film so as to cover the IDT electrode to thereby reduce the absolute value of the frequency temperature coefficient TCF. Japanese Unexamined Patent Application Publication No. 2008-522514 also discloses that the IDT electrode has a structure in which various metal films are laminated, and therefore the reflection intensity of surface waves can be adjusted by controlling the film thickness of each metal film in a specific range. The film thickness of the dielectric film containing SiO2 is about 20% to about 40% of the wavelength λ of surface acoustic waves.
However, in the surface acoustic wave device of Japanese Unexamined Patent Application Publication No. 2008-522514, since the insertion loss is not low, it is required to further reduce the insertion loss. Moreover, the thickness of the dielectric film is relatively as thick as about 20% to about 40% of the wavelength. Therefore, the electromechanical coupling coefficient is not so high. When used as a band-pass filter, it has been difficult to broaden the bandwidth.


A color cathode ray tube and an envelope for use with the color cathode ray tube in which a metal plate is interposed between a panel section and a plurality of funnel and neck sections, each of which combination having one electron gun disposed internally. The overall length of the envelope thus constructed can thus be shortened in the direction of the tube axis. The structure of the envelope can also be more simply made and ease of production provided. Further, the envelope can be made lighter in weight.

1. Field of the Invention
The present invention relates to a color cathode ray tube and, more particularly, it relates to the structure of an envelope provided with plural necks and a color cathode ray tube provided with this envelope.
2. Description of the Related Art
The conventional color cathode ray tube provided with a plurality of necks is shown in FIG. 1. As disclosed in Japanese Patent Disclosure No. Sho 61-256551, this color cathode ray tube 1 includes envelope 11 comprising panel section 2 provided with a substantially rectangular face plate 4 and a skirt 6 extending from the circumferential rim of face plate 4, a funnel section 8 connected to a panel section 2, and a plurality neck sections 10 continuous from funnel section 8. The inside of cathode ray tube 1 is kept in a vacuum by the panel, the funnel and neck sections 2, 8 and 10. An electron gun assembly 12 for shooting three electron beams is housed in each of a neck sections 10. The funnel and neck sections 8 and 10 are provided, on the outer surface thereof, with a deflection means 14 for generating a magnetic field to deflect the electron beams in the horizontal and vertical directions. A phosphor screen 16 is formed on the inner surface of the face plate 4 at the panel section 2. A substantially rectangular shadow mask 18 is arranged inside the tube, facing the phosphor screen 16 with a certain interval interposed between them. The shadow mask 18 is made of a thin metal plate and is provided with a plurality of slit apertures 20. Frame 22 is attached to the circumferential rim of shadow mask 18.
Three electron beams shot from each of the electron guns 12 are deflected by deflection means 14. FIG. 1 shows those areas where the three electron beams are deflected. The electron beams thus deflected converge on the phosphor screen 16. The electron beams thus converged are introduced onto the phosphor screen 16 to emit the three colors of red, green and blue. Phosphor screen 16, which is scanned by the electron beams shot from electron guns 12, is sectioned to correspond to each of electron guns 12.
In the case of the envelope having the above-described structure to be used as the color cathode ray tube, the distance extending from the face plate to the neck can be made shortened as compared with another envelope, the same in size, but having only one neck section. This is because that area of the phosphor screen which is scanned by the electron gun housed in the neck section can be made smaller and the distance between the electron gun and the phosphor screen can thus be shortened. As the envelope is made larger in size, the effect of making this distance shorter can be enhanced further and further. In the case where the panel, funnel and neck sections are all made of glass, however, they cannot be made so sharply-curved as to make the distance between the electron gun and the phosphor screen shorter because the material of which they are made is glass. An envelope made of glass is therefore limited in how short the distance can be made.
The envelope having the above-described arrangement to be used as the color cathode ray tube has an extremely more complicated shape as compared with the other envelopes which are intended for the common color cathode ray tubes. In common color cathode ray tubes, this envelope is made of glass. It is therefore quite difficult to process glass to the complicated shape of this envelope. This makes it difficult to put this envelope into mass production.
This envelope is made to resist atmospheric pressure so as to maintain an inside vacuum. When it is large in size, quite a large force is added to it because of atmospheric pressure. It is therefore necessary for the thickness of the glass funnel section to be substantially the same as that of the glass panel section. However, a distortion of the glass neck section by the pressure is relatively small. It is therefore unnecessary to make the thickness of the glass neck section large. The glass neck section may be about 1 mm thick, for example. The thickness of glass thus changes sharply from the funnel to the neck section and this changes heat capacity sharply at the portion where the glass shifts from the funnel to the neck section. During manufacture, heat is applied to the envelope at a plurality processes thus increasing its thermal distortion. Because the envelope is made more likely to be broken because of thermal distortion, it is difficult to put the glass envelope on a mass production line. Further, the thickness of the funnel section is made substantially the same as that of the panel section. When the envelope is large in size, therefore, it becomes quite heavy. When it is heavy, it increases the weight of the color cathode ray tube for which it is intended.

Color cathode ray tube and envelope for use with the color cathode ray tube


A system is disclosed that is capable of validating a selected record of a digital ledger, receiving input that a player has interacted with the gaming system, and, in response to receiving input that the gaming system has interacted with the player, exiting the digital ledger validation mode and entering a game mode in which the gaming system plays a game session with the player.

The present disclosure is related to gaming systems and devices and, in particular, the use of such devices in connection with validating digital ledgers.
As gaming systems, such as electronic gaming machines (EGMs) and lottery vending machines, offer more features to players, the price of gaming systems has continued to rise. The higher price is commonly not offset by high levels of usage. A typical gaming system has significant idle time between play sessions. These can be extended idle periods, particularly late at night or early in the morning.

Gaming system for validating digital ledgers


A data processing apparatus executes one or more computer program applications. The data programming, apparatus is operable to display at least one resizable graphical element from a plurality of resizable graphical elements on a display and resize the at least one displayed graphical element in response to a resize control input from a user control. The data processing device is operable to switch between which of the plurality of graphical elements is displayed if the displayed graphical element is resized to be greater in size or to be less in size than one of a plurality of predetermined threshold sizes. Each of the plurality of graphical elements includes at least one graphical object or interface control different from the other graphical elements of the plurality of graphical elements and a greater a size of one of the plurality of predetermined threshold sizes, a greater a number of controls and/or graphical objects included in the graphical element that is displayed when the displayed graphical element is resized to exceed that predetermined threshold size.

Data processing devices such as portable personal computers, mobile telephones, personal media devices and so on, provide users with an increasing number of functions. For example, even a relatively inexpensive mobile telephone might nowadays be expected to provide functions including audio/video playback, internet access, email, content streaming, instant messaging, satellite assisted navigation functionality and so on.
Providing a graphical user interface that enables a user to easily and conveniently understand and use all the available functionality on such devices can be quite difficult. Conventional personal computer "desktop" type graphical user interfaces in which the various functions available to a user are accessed by selecting an icon or the like are less appropriate for data processing devices with limited display space. Moreover, such conventional graphical user interfaces can become increasingly difficult to use when there are a large number of functions available to chose from and display.


The present disclosure relates to cellulose nanomaterials made or derived from tobacco and methods for the production thereof. The tobacco-derived cellulose nanomaterials can be employed in various industrial applications such as film forming applications and solution thickening technologies. In particular, the disclosure is directed to methods for preparing tobacco-derived cellulose nanomaterials using less fibrillation cycles than in the production of wood pulp. The invention includes a method for preparing tobacco derived nanocellulose material comprising receiving a tobacco pulp in a dilute form such that the tobacco pulp is a tobacco pulp suspension with a consistency of less than about 5%; and mechanically fibrillating the tobacco pulp suspension to generate a tobacco derived nanocellulose material having at least one average particle size dimension in the range of about 1 nm to about 100 nm.

Cellulose nanomaterials are isolated from trees, plants, and algae or can be generated by bacteria. Different raw material sources, as well as different production methods, will lead to cellulose nanomaterials with differing morphology and properties, such as length, aspect ratio, branching and crystallinity. With respect to commercialization, two major categories of cellulose nanomaterials have received the greatest interest: cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs). CNCs and CNFs are obtained from a variety of cellulose sources, such as wood, using various processing methods. For example, CNCs are produced by acid hydrolysis of wood fiber, whereas CNFs are produced using mechanical processes with or without pre-treatment procedures requiring chemicals or biological treatments to produce fibril-like nanoscale materials. The ability to produce such a wide range of cellulose nanomaterials with different morphologies and properties represents a whole variety of potential applications across multiple industries.
However, the production of cellulose nanomaterials is time and energy consuming. The production of native grades usually requires multiple cycles in the fibrillation stage when commercial mill pulp is used. The degree of fibrillation can be affected by the selection of pre-treatments and choice of raw materials. Currently, the most common raw material is wood pulp, which forms a viscous hydrogel after multiple passes in a grinder or high pressure homogenizer. Since the fibrillation time is the most significant cost factor in the production of cellulose nanomaterials, there is a great need to develop processing methods with a reduced number of fibrillation cycles. In addition, there is a need in the art for more biomaterials as potential sources for raw materials in the production of cellulose nanomaterials, which require production processes that are more cost efficient.

This patent is subject to a terminal disclaimer.


A non-aqueous biodegradable negative photoresist stripping composition having low toxicity and is operable at temperatures at 85.degree. C. or less which comprises about 85% by weight of an aromatic hydrocarbon solvent of the formula selected from the group consisting of: ##STR1## wherein R.sub.1 and R.sub.2 are the same or different and each is a member selected from the group consisting of methyl, ethyl n-propyl and isopropyl, and an organic sulfonic acid of the formula: EQU R.sub.3 --SO.sub.3 H. wherein R.sub.3 is a member selected from the group consisting of phenyl, tolyl, dodecylbenzene and naphthyl, the ratio of the aromatic solvent to organic solvent acid being about 60 to 96% by weight to about 4 to 40% by weight.

During manufacture of semiconductors and semiconductor microcircuits, it is frequently necessary to coat the materials from which the semiconductors and microcircuits are manufactured with a polymeric organic substance, generally referred to as a photoresist, e.g., a substance which forms an etch resist upon exposure to light. These photoresists are used to protect selected areas of the surface of the substrate, e.g. silicon, SiO.sub.2 or while such etchant selectively attacks the unprotected area of the substrate. Following completion of the etching operation and washing away of the residual etchant, it is necessary that the resist be removed from the protective surface to permit essential finishing operations.
It is necessary in a photolithographic process that the photoresist material, following pattern delineation, be evenly and completely removed from all unexposed areas, in the case of positive resists, or exposed areas in the case of negative resists, so as to permit further lithographic operations. Even the partial remains of a resist in an area to be further patterned is undesirable. Also, undesired resist residues between patterned lines can have deleterious effects on subsequent processes, such as metallization, or cause undesirable surface states and charges.
A common method used in removing the photoresist from the substrate is by contacting the substract with an organic stripper. Heretofore these organic strippers have been composed of various components whose purpose it was to lift and remove the polymeric photoresist from the substrate. However, these stripping solutions have heretofore usually contained phenol or phenol compounds and chlorinated hydrocarbon compounds which resulted in a distinct disadvantage due to the toxicity of phenol as well as the pollution problems arising from the disposal of phenol or phenol compounds such as cresols, phenol sulfonic acid and the like or the disposal of chlorinated hydrocarbon compounds.
Phenol-free and chlorinated hydrocarbons-free strippers are described in U.S. Pat. No. 4,070,203 (issued Jan. 24, 1978 to Neisus et al). These strippers, having only an alkylbenzenesulfonic acid component of 12-20 carbons and a chlorine-free, aromatic hydrocarbon component with a boiling point about 150.degree. C., suffer from the disadvantage that they cannot be easily rinsed off the inorganic substrate after stripping with aqueous rinsing materials such as deionized water. Instead organic solvents are required to avoid either the polymer or the aromatic solvent precipitating or forming oil beads, respectively, or, if water is used, copious amounts are required. The formation of oil beads is called "oiling out" and may lead to an undesirable oily layer remaining on the inorganic substrate.
There are various and numerous drawbacks and disadvantages with the prior art materials. Among the one or more drawbacks and disadvantages found in the use of each such stripping agents there may be mentioned the following: undesirable flammability, volatility, odor and toxicity; incomplete removal of all resist film; effectiveness only on certain resist films; attack of metal substrates by the stripping agent, safety in handling and disposal of the stripper; and the undesired necessity for use at specified elevated temperatures when selected resists are being stripped. Furthermore, the limited stripping capabilities of the stripping agents are a very decided drawback. Additionally, many such strippers are not sufficiently effective against resist materials that are subject to a severe post-baking operation thereby limiting their usefulness. In some of the strippers the presence of water is extremely detrimental. Additionally, for those stripping applications requiring inertness of the agent to metal substrates, toxicity during handling and difficulty of disposal are primary drawbacks.
OSHA, EPA and other similar federal, state and local governmental regulatory agencies have advocated a shift toward use of more human and environmentally compatible stripping compositions and stripping methods that are not subject to the aforementioned drawbacks and problems.
Moreover, heretofore available stripping compositions have required unduly long residence times or repeated applications in order to remove certain coatings. In addition, various coatings have resisted removal from certain substrates with these heretofore available stripping compositions. That is, these previously available stripping compositions have not provided adequate or complete removal of certain hard-to-remove coatings from various substrates.
It is, therefore, highly desirable to provide stripping compositions that exhibit substantially no human or environmental toxicity, and are biodegradable. It is also desirable to provide stripping compositions that are substantially non-corrosive, evidence relatively little, if any, tendency to evaporate and are generally unreactive and also of little toxicity to humans and are environmentally compatible. It would also be most desirable to provide stripping compositions that are recyclable, if desired, and thus available for extended bath life and multiple use.
Moreover, it would be desirable to provide stripping compositions that have a high degree of stripping efficacy and particularly such high degree of stripping efficacy at lower temperatures than generally required with prior stripping compositions.
It is also highly desirable that stripping compositions be provided that exhibit very low vapor pressure at elevated temperatures, thereby significantly reducing evaporation and thus contamination of the atmosphere.
Additionally, it is highly desirable that such compositions be provided that are effective and efficient stripping compositions for removal of coatings from substrates that heretofore have resisted ready removal with conventionally available strippers.
It is also desirable that effective stripping compositions be provided that are devoid of undesirable chlorinated or phenolic components and which do not require the use of hot caustic components. Highly desirable are stripping compositions and use thereof that are not considered undesirable by regulatory agencies overseeing their production and use.
U.S. Pat. No. 4,165,294 to John E. Vander Mey discloses a stripping solution free from phenol and chlorinated hydrocarbons comprising a surfactant, an alkylarylsulfonic acid and an aromatic hydrocarbon having a boiling point above 150.degree. C. The aromatic hydrocarbons are optional and are preferably mixtures of aromatic solvents having 9-13 alkyl carbons and do not comprise more than 40 weight percent.
U.S. Pat. Nos. 4,426,311; 4,395,348; 4,304,681; 4,221,674; 4,215,005 and 4,165,295 each disclose the use of an organic sulfonic acid in a photoresist stripping composition. However, the organic sulfonic acid is utilized in combination with solvents having the aforementioned disadvantages.
It is an object of the invention to provide a non-aqueous biodegradable negative photoresist stripping composition which can be used at a wide range of operating conditions and at lower temperatures.
It is another object of this invention to provide a photoresist stripping solution which is essentially free of phenol, phenol compounds and chlorinated hydrocarbon compounds.
It is an additional object of this invention to provide such a solution which is substantially clean water rinseable such that the hydrocarbon solvent does not oil out and the polymer does not reprecipitate during rinsing.
It is an additional object of this invention to provide a method for removing photoresist polymeric coatings from inorganic substrates with such a stripping solution free from phenol, phenol compounds which can then be rinsed with an aqueous rinsing agent such as deionized water.


Light-emitting elements having high emission efficiency and long lifetime can be provided. By forming light-emitting devices including the light-emitting elements, the light-emitting devices having low power consumption and long lifetime can be provided. A light-emitting device comprises a light-emitting element including a light-emitting layer between a first electrode and a second electrode. The light-emitting layer includes a first organic compound having a hole-transporting property, a second organic compound having an electron transporting property, and an organometallic complex. A central metal of the organometallic complex is an element belonging to one of Group 9 and Group 10, and a ligand of the organometallic complex is a ligand having a pyrazine skeleton.

In recent years, a light-emitting element using a light-emitting organic compound or inorganic compound as a light-emitting substance has been actively developed. In particular, a light-emitting element called an EL element has a simple structure in which a light-emitting layer containing a light-emitting substance is provided between electrodes. Therefore, the light-emitting element has attracted attention as a next-generation flat panel-display element because of its characteristics such as a thin shape, lightweight, high response speed, and direct current driving at low voltage. In addition, a display using such a light-emitting element has a feature that it is excellent in contrast and image quality, and has a wide viewing angle. Further, since these light-emitting elements are plane light sources, it is considered that these light-emitting elements are applied as light sources such as a backlight of a liquid crystal display and an illumination device.
In a case of using a light-emitting organic compound as a light-emitting substance, the emission mechanism of a light-emitting element is a carrier injection type. Namely, by application of a voltage with a light-emitting layer interposed between electrodes, carriers (holes and electrons) injected from the electrodes are recombined and thus a light-emitting substance is made to be in an exited state. Light is emitted when the excited state returns to the ground state. As the type of the excited state, a singlet excited state (S*) and a triplet excited state (T*) are possible. The statistical generation ratio thereof in a light-emitting element is considered to be S*:T*=1:3.
In general, the ground state of a light-emitting organic compound is a singlet excited state. Therefore, light emission from a singlet excited state (S*) is referred to as fluorescence because it is caused by electron transition between the same multiplicities. On the other hand, light emission from a triplet excited state (T*) is referred to as phosphorescence because it is caused by electron transition between different multiplicities. Here, in a compound emitting fluorescence (hereinafter referred to as a fluorescent compound), in general, phosphorescence is not observed at room temperature, and only fluorescence is observed. Therefore, in a light-emitting element using a fluorescent compound, the theoretical limit of internal quantum efficiency (the ratio of generated photons to injected carriers) is considered to be 25% based on S*:T*=1:3.
On the other hand, when a compound emitting phosphorescence (hereinafter referred to as a phosphorescent compound) is used, internal quantum efficiency can be theoretically 75 to 100%. In other words, luminous efficiency can be three to four times as high as that of a fluorescent compound. From these reasons, in order to achieve a light-emitting element with high efficiency, a light-emitting element using a phosphorescent compound has been proposed (for example, Non Patent Document 1: TSUTSUI et al., HIGH QUANTUM EFFICIENCY IN ORGANIC LIGHT-EMITTING DEVICES WITH IRIDIUM-COMPLEX AS A TRIPLET EMISSIVE CENTER, JPN. J. APPL. PHYS. (JAPANESE JOURNAL OF APPLIED PHYSICS), vol. 38/PART. 2, No. 12B, 15 Dec. 1999, pages L1502-L1504 and Non Patent Document 2: ADACHI et al., HIGH-EFFICIENCY RED ELECTROPHOSPHORESCENCE DEVICES, APPL. PHYS. LETT. (APPLIED PHYSICS LETTERS), vol. 78, No. 11, 12 Mar. 2001, pages 1622-1624. Non Patent Documents 1 and 2 employ an iridium complex using a ligand of 2-phenylpyridine (Ir(ppy)3) and a ligand of 2-(2′-benzo[4,5-a]thienyl)pyridine ([btp2Ir(acac)]) as phosphorescent compounds, respectively.
Further, Patent Document 1 discloses a light-emitting element using a light-emitting layer which contains, as a host material for a phosphorescent dopant, an organic low molecular hole-transporting substance and an organic low molecular electron-transporting substance in order to improve the lifetime and efficiency of the light-emitting element using a phosphorescent compound (Patent Document 1: Japanese Translation of PCT International Application No. 2004-515895).

Light-emitting device using organometallic complex having a pyrazine skeleton

Semiconductor Energy Laboratory Co., Ltd.


A current source circuit can include a first amplifier circuit and a second amplifier circuit. Each of the first and second amplifier circuits can be configured to generate respective amplifier output voltages based on a corresponding input voltage and respective feedback voltage. The current source circuit can further include a cross-coupling circuit that can include a first set of resistors and a second set of resistors. The first set of resistors can be configured to establish a first cross-coupling voltage based on the first amplifier output voltage and the second set of resistors can be configured to establish a second cross-coupling voltage based on the second amplifier output voltage. The first and second amplifier circuits can be configured to maintain the first and second cross-coupling voltage at a given voltage amplitude to provide a constant current at an output node of the current source circuit.

A current source is an electronic circuit that delivers or absorbs an electric current which is independent of the voltage across the current source. A constant-current source circuit can generate a current that is relatively stable against variations of power supply voltage. Constant current sources are used in various applications to provide a constant current, such as device under testing (DUT) applications to verify characteristics or a performance of a DUT.


The new blueberry plant variety ‘Clockwork’ is provided. ‘Clockwork’ is a commercial variety with excellent machine harvest characteristics, and is intended for the processed foods market. The variety has a concentrated mid-season ripening schedule, with the potential to be harvested only once per season. ‘Clockwork’ holds up well in freezer trials, with excellent flavor and texture. The plant is vigorous, with an upright growth habit, and has an estimated chilling requirement of 800 to 1,000 hours.

The present invention relates to the discovery of a new and distinct cultivar of northern highbush blueberry known as a Vaccinium corymbosum referred to as 'Clockwork', as herein described and illustrated.
The new blueberry plant variety 'Clockwork' was selected in Lowell, Oreg. in 2005. 'Clockwork' is a commercial variety with excellent machine harvest characteristics, and is intended for the processed foods market. The variety has a concentrated mid-season ripening schedule, with the potential to be harvested only once per season. 'Clockwork' holds up well in freezer trials, with excellent flavor and texture. The plant is vigorous, with an upright growth habit, and has an estimated chilling requirement of 800 to 1,000 hours.
Pedigree and History: The new blueberry plant originated from a cross of 'Reka' (female parent, U.S. Plant Pat. No. 6,700, expired) by 'US645' (pollen parent, unpatented). The new blueberry plant variety 'Clockwork' has been planted in replicated trials since 2007.
The new variety can be compared to commercial variety 'Duke' in that 'Clockwork' ripens about 2 weeks later, has a smaller berry with a shallow calyx and has more concentrated ripening.
The new variety can be compared to commercial variety 'Draper' (U.S. Plant Pat. No. 15,103) in that 'Clockwork' has more concentrated ripening, a smaller berry with a shallow calyx, and a higher yield.
The new blueberry plant variety 'Clockwork' has maintained its distinguishing characteristics throughout successive asexual propagations. The variety has been repeatedly asexually reproduced through softwood cuttings in Lowell, Oreg., and the clones are phenotypically identical to the original plant.


A method of producing a high purity silica powder which can be fused to form transparent, bubble-free particles. An ammonium fluosilicate solution is purified preliminarily by removing colloidal-sized silica onto which impurities in the solution have been adsorbed. The high purity powder is produced by ammoniation of an unsaturated aqueous solution of ammonium fluosilicate. Silica powder produced is filtered, washed, and dried before fusion. Additional pre-fusion treatments such as washing, hydrothermal leaching, calcination, and a combination thereof, may be utilized to ensure that the concentration of volatile material is low.

1. Field of the Invention
The present invention relates to a method for producing high purity silica powder which can be fused to form transparent, bubble-free particles. More particularly, the invention relates to a method of recovering such fusible high purity silica powder from an unsaturated solution of ammonium fluosilicate.
2. Description of Related Art
Silica powder typically is produced in a number of ways to serve a variety of purposes. For example, silica can be produced by hydrolysis of a silicon tetrahalide or other silicon-containing compounds, such as tetraethylorthosilicate. These methods typically are not completely satisfactory. Hydrolysis of silicon tetrachloride, for example, can require days to form a gel, while tetraethylorthosilicate is a very expensive raw material.
Silica products produced by these methods typically are suitable only for selected uses. As an example, silica made by ammoniation of ammonium fluosilicate, for example, as taught in U.S. Pat. No. 1,903,187, is useful as adsorbent, but cannot readily be fused to form transparent, bubble-free particles suitable for use in encapsulation of electronic parts or other high-purity, high-density uses described below. According to this patent, ammonium fluosilicate produced during recovery of metals from silicates is ammoniated to produce silica acid precipitate.
U.S. Pat. No. 2,768,063 also discloses a method for producing silica by ammoniating ammonium fluosilicate solution. Ammonium fluosilicate solution which has been filtered to remove insoluble matter is introduced into an excess of aqueous ammonium solution and finely divided amorphous silica is precipitated. The silica is washed and utilized as the "frosting" for the inside of light bulbs. The patent indicates that the temperature of both solutions should be between about 25.degree. and 37.degree. C., and it is important to add the ammonium fluosilicate solution to the ammonium solution. Adding the ammonium solution into the ammonium fluosilicate solution is said to produce too much gel.
U.S. Pat. No. 3,271,107 discloses a process for producing a silica used in pigments by reacting fluosilicic acid with ammonium hydroxide in two stages. Fluosilicic acid is a by product of, e.g., phosphoric acid manufacture, and is produced when silicon tetrafluoride liberated during concentration of phosphoric acid is absorbed in water. Other fluosilicic acid sources are known to those skilled in the art. In the first stage, a less-than-stoichiometric quantity of ammonium hydroxide is added to fluosilicic acid with high agitation to produce a slurry having a pH of between 6.0 and 8.0 containing minute silica particles. The unreacted fluosilicic acid in this slurry then is reacted with sufficient ammonium hydroxide to provide a final pH between about 8.3 and 9.0. Pigment quality silica precipitate then is separated from the slurry.
U.S. Pat. No. 3,021,194 discloses a process for producing ammonium bifluoride from fluosilicic acid and ammonium fluoride without undue loss of ammonia or fluorine. Concentrated fluosilicic acid is reacted with ammonium fluoride, or a mixture of ammonium fluoride and sodium or potassium fluoride, to produce aqueous ammonium acid fluoride (ammonium bifluoride) solution and solid alkali fluosilicate, including ammonium fluosilicate. After separating the solution from the solid alkali fluosilicates, solid ammonium bifluoride is recovered by evaporatively concentrating the solution. Alkali metal fluosilicates can be recovered and sold, or can be converted to alkali fluorides by reaction with additional ammonia. Ammonium fluoride is produced and hydrated silica is precipitated by this ammoniation. The silica is indicated for use as a filler, a flatting agent, or as an insecticide provided it contains some sodium fluoride.
Certain uses of silica require very high purity material. For example, silica used in the encapsulation or packaging of electronic computer chips must have extremely low levels of metal impurities. Typical of these uses is very large scale integrated (VLSI) microchip applications, where chip manufacturers require silica having extremely low concentrations of certain radioactive elements. For example, uranium and thorium concentrations must be on the order of less than 1 part per billion (ppb). The maximum acceptable level of ionic impurities, including cations such as boron, calcium, cobalt, chromium, copper, iron, potassium, magnesium, manganese, sodium, nickel, vanadium, and zinc, and anions containing phosphorus and sulphur, is less than 10 parts per million (ppm), and often is below 1 part per million. The concentration of halogens also should be minimized to reduce chip corrosion and increase chip life.
Other uses for high purity silica material include precision laser optics, fiber optics, and advanced ceramics. These requirements now are satisfied predominantly by natural silica sources such as quartz. Although natural quartz is a crystalline form of silica, such quartz can be made amorphous by fusion techniques known to those skilled in the art. Thus, modified quartz, often called "fused quartz," suitably is used when amorphous silica is required. Unfortunately, prior art processes for recovering silica from contaminated fluosilicic acid starting materials, such as by-product fluosilicic acid recovered from phosphate rock acidulation, have not been satisfactory for producing a product satisfying these stringent purity requirements.
U.S. Pat. No. 4,465,657, for example, discloses a process for producing a purified silica from impure fluosilicic acid which basically uses the procedure of the earlier U.S. Pat. No. 3,271,107. Fluosilicic acid is reacted in a first step with a less--than--stoichiometric quantity of ammonium hydroxide to convert some of the acid to ammonium fluoride and silica. The silica precipitate thus produced removes metal ion impurities, presumably at least in part by adsorption, from the residual fluosilicic acid solution. The silica precipitate is separated, and the remaining solution having a lower level of impurities then is reacted in a second stage with additional ammonium hydroxide to produce a purified silica precipitate. Optionally, the residual fluosilicic acid solution from the first precipitation stage may be treated with an ion exchange or chelating agent to purify the solution further prior to formation of the silica precipitate in the second precipitation stage.
A particular drawback of this procedure is that from 40 to 75 percent of the available silica in the fluosilicic acid is used as the vehicle for removing impurities. Thus, only 25 to 60 percent of the silica values of the fluosilicic acid actually can be recovered in a purified form. Moreover, there is a tacit admission that the two step process does not produce a satisfactory product since it is preferred to treat the solution from the first step process with an ion exchange or chelating agent prior to the second precipitation step.
European Patent Application 0,113,137 attempts to avoid the loss in yield of U.S. Pat. No. 4,456,657 by adding a chelating agent directly to the impure fluosilicate acid solution. Purportedly, the chelating agent improves the purity of the first silica precipitate by sequestering or chelating multivalent metal ions in the solution before ammoniation. Ion exchange also has been used for the same purpose. However, these techniques tend to introduce other impurities, such as alkali metal ions, into the precipitated silica. Additionally, these prior art purification processes rely upon cationic exchangers and metal chelating agents and thus cannot satisfactorily remove the phosphorus and sulphur impurities generally present as anionic species (SO.sub.4.sup.-2 and PO.sub.4.sup.-3) in the fluosilicic acid by-product solutions typically recovered from the acidulation of phosphate rock. Nor can anionic exchange agents be used because the anionic exchange agents significantly decrease the recovery of silica.
Silica produced in accordance with these methods is not satisfactory for use in producing high purity, transparent, bubble-free particles because the silica product contains too many impurities. With respect to silica produced by ammoniating ammonium fluosilicate, the subsequently fused particles are not transparent and bubble-free. Methods known in the art for producing fusible silica are complex and difficult to carry out. One alternative, natural quartz, is very expensive and reserves are limited. Further, natural quartz typically is not acceptable for high purity fused product unless it is purified.
Japanese Patent 85(60)/42218 teaches a method of producing high purity silica suitable for electronic uses, for use as a filter for plastic resin, for use in adhesives, and the like. An aqueous solution of an alkali silicate is ultrafiltered to remove colloidal-sized particles. The filtered solution then is purified first with an acidic cation exchange resin, and then with an OH-type anion exchange resin, to obtain a purified silica sol. The purified silica sol is contacted with a precipitant such as ammonium chloride, ammonium nitrate, or ammonium carbonate to cause silica to precipitate. Precipitated silica is collected, then heated.
Soviet Union Patent 776,994 discloses a method for producing transparent, bubble-free quartz glass. Carbon dioxide is bubbled through a sodium metasilicate solution. A precipitate is formed which is washed, and then treated in acid at 130.degree.-200.degree. C. for at least about four hours. Treated precipitate subsequently is filtered, washed, briquetted, fired, and ground. The ground particles are vibro-sorted to segregate a fraction having a density between 1.4 and 1.6 g/cm.sup.3, and then are fused to obtain quartz glass.

Method of production of high purity fusible silica


A radiation hardened CMOS transistor has a source region, drain region and channel region formed on an SOI or SOS wafer. End plugs of opposite conductivity to that of the source and drain regions are connected to the channel region. In one embodiment, the end plugs extend along opposite ends of the source region but not along the drain region. In another embodiment, the end plugs extend along opposite ends of the source region and the drain region, and the drain region includes portions adjacent the end plugs having an impurity concentration which is significantly lower than the impurity concentration of the remainder of the drain region. The transistor is surrounded by a silicon dioxide isolation region. Contact holes for establishing electrical contact are positioned over areas in which the source region interfaces with each of the end plugs, and over an area of the drain region. The end plugs are electrically tied to the source region through common metallized contacts so that radiation sensitive parasitic actions may be prevented.

The present invention is directed to semiconductor devices and particularly to CMOS SOI or SOS devices having radiation hardened characteristics.
Silicon-on-Insulator (SOI) technology has received considerably attention recently for development of high-density, radiation-hardened integrated circuits. The technology offers good potential for achieving a combination of radiation hardness and circuit density levels not attainable by bulk complementary metal oxide semiconductor (CMOS) or dielectrically isolated bipolar implementations. Interest in the technology has also been amplified by the recent availability of improved-quality oxygen-implanted SOI wafers. In particular, the SIMOX (Separation by IMplanted OXygen) approach is being considered as a production-capable process for providing high-quality SOI wafers. The following reference generally describes this technology. S. S. Tsao, D. M. Fleetwood, H. T. Weaver, L. Pfeiffer, and G. K. Cellar, "Radiation-Tolerant Sidewall-Hardened SOI/MOS Transistors," IEEE Trans. Nucl. Sci., Vol. NS-34, p. 1692, Dec. 87. This invention describes a fairly simple approach to development of radiation-hardened CMOS/SOI devices.
In CMOS/SOI radiation hardening, recent emphasis has mostly been on sidewall isolation, and two isolation approaches have been reported, The isolated mesa approach (with sloped sidewall) is an extension of device isolation techniques employed in CMOS/SOS where a MOS device is formed on a silicon layer on top of a sapphire substrate. Hardening of the sidewall in this case is implemented by using an appropriate hardened gate dielectric on the sidewall. There are some drawbacks with this approach: the sidewall transistor has different characteristics than the top channel transistor. The sidewall channel also connects the top channel to the back channel, which is not desirable due to potential corner effects: at the corners, the channel sees both the sidewall gate dielectric and the buried oxide. Even if the sidewall gate dielectric is hardened, buried oxide could cause radiation-inducted leakage at the two corners. Finally, the wafer topography is non-planar in this approach, and unless an effective planarization process is employed, it would have a low yield in metal definition.
Planarized polysilicon-filled trench isolation is another technique that has been applied for sidewall hardening. The sidewall hardness problem exists for oxide-isolated NMOS transistors because the channel along the sidewall can invert due to charge buildup in the isolation oxide. By using a polysilicon-filled trench in place of oxide isolation, the charge buildup problem can be reduced. However, this approach requires both the growth of a hardened gate oxide on the sidewall and a fairly difficult trench-definition-and-filling process, and these two requirements are not necessarily compatible. An important advantage of CMOS/SOI (or SOS) is its relative simplicity in device structure as compared to bulk CMOS. The addition of a difficult trench isolation process would detract from this advantage.

Radiation hardened CMOS on SOI or SOS devices

The United States of America as represented by the Secretary of the Air Force


A Viterbi decoder capable of supporting a variety of constraint lengths and any arbitrary number of coefficients of a given estimated transmission path and composed of special hardware of small circuit scale. In the Viterbi decoder of the present invention, a branch metric calculation section (101) calculates the branch metrics of all paths from the state of the previous time to the state at the present time, selects the most probable path from the paths arriving at respective states based on the branch metrics (101a) and path metrics (103a) and outputs path select signal (102a) and path metric (102b). Path metric storage section (103) outputs path metric (103a) to be input to ACS calculation section (102) when performing ACS calculating at the next time. Path select signal temporary storage section (104) holds path select signal (102a) of n states, outputs path select signal (104a) of m states (m≦n) and changes a bit input position according to the encoding constraint length or the number of coefficient of deduced estimated transmission path of the system which performs Viterbi decoding.

Viterbi decoders of this type have high error correction capability and are employed in information communication systems such as decoding apparatus and receiving apparatus for use with transmission schemes for satellite communication and mobile communication where errors are more likely to occur.
Viterbi decoding accomplishes decoding through performing a process of finding the difference (branch metric) between received data sequence and expected data sequence, repeating simple processing (ACS) of addition, comparison and selection, and traceback processing of decoded data finally. With this Viterbi decoding, every time coded data corresponding to one input bit is obtained, the distance between signals of the paths of each state at this time is calculated and remaining paths are found.
For example, when the coding scheme is convolutional coding, Viterbi decoding processing is performed as follows.
The convolutional code is generated from the exclusive logical sum of input bit and preceding a fixed number of bits and a prefixed number of preceding bits, and a plurality of coded data is generated in response to one input bit. The number of input bits (information bits) having influence on this coded data is called constraint length K, and the number is equivalent to the number of stages of shift registers used with exclusive logical sums.
The coded data is defined by the state of input bit and (K−1) preceding input bits. These states shift to new states when new input bit is input. However, whether or not a state can be shifted is determined depending on whether the new input is "0" or "1." The number of states becomes (2K−1) because each of (K−1) bits can be "0" or "1."
In Viterbi decoding, a received coded data sequence is observed and the most probable state is estimated from all possible states. Therefore, in Viterbi decoding, every time coded data corresponding to one input bit is obtained, the distance between signals (metric) of the paths of each state at the time is calculated, and, among paths that reach the same state, the path having the smaller path is left as a remaining path.
FIG. 1 shows that, in a convolutional encoder with a constraint length K, two paths are expanding respectively, indicating state shift from the state of S[j] and S[j+m/2] at time t−1 of previous time to the state of S[2j] and S[2j+1] at time t. Here, j represents a positive integer number and m represents the number of states.
In FIG. 1, path metric A1 is a sum of the distance between signals (branch metric B1) of expected data sequence and received data sequence that are output when shifting to state S[2j] and path metric PM[j] to state S[j] at previous time.
Likewise, path metric A2 represents a sum of the distance between signals (branch metric B2) of expected data sequence and received data sequence that are output when shifting to state S[2j] and path metric PM[j+m/2] to state S[j+m/2] at previous time.
Thus calculated path metric A1 and A2, which are input to state S[2j], are compared, and the smaller path is selected as a remaining path. Further, the path metric of the selected path is renewed as a path metric until reaching state S[2j] at present time t.
In addition, history of which of path metric A1 and A2 is selected is left as path select signal PS[i] (i=0˜2k−1−1). At this time, when the previous state number of the selected path is smaller than the previous state number of the other, unselected path, PS[i] is 0, or is 1 otherwise.
These processes are performed as many times as the number of times of: the number of states multiplied by traceback length. Further, path select signals of: the number of states multiplied by traceback length; and path metrics of the number of states at final time, are obtained. After that, traceback is performed and coded data is decoded with these information.
Next, the traceback processing will be explained briefly with reference to FIG. 2. FIG. 2 is a trellis diagram showing a history of shifting of each state at the time when number of times of processing of the state number multiplied by length, given that constraint length is "3" and traceback length is "7," is finished. Numerical values on the line between states represent path select signals when each state is shifting and path described in a solid line is a remaining path.
In the traceback processing, the path metric of each state at the final time is referred to and the state in which path the metric becomes the smallest is selected. However, when known data sequence is attached to input data sequence of coded data as tail bit, the state indicated by this tail bit is uniquely selected (assuming S[00] is selected in this example). Next, the state goes back to the state one time earlier than the path select signal selected at final time. In addition, the path select signal at this time is output as decoded data. Similarly, subsequently, decoded data of traceback length is output following back the states (the path shown in bold line in FIG. 2) at every unit of time based on the path select signal. This processing makes it possible to decode the decoded data sequence (in this case, 1→0→1→1→0→0→0).
By the way, with this Viterbi decoder, the error correction capability improves as the constraint length becomes larger, and the processing amount increases by increasing the constraint length. Therefore, in conventional information communication systems, a coding scheme having a large constraint length is employed when information source which requires high error correction capability is transmitted, and a coding scheme having a short constraint length is employed when information source which tolerates a certain amount of errors is transmitted. However, with schemes like this, in one information communication system, signals that are coded by a plurality of constraint lengths need to be decoded.
On the other hand, when equalization processing of received signal is performed, it is possible to perform equalization processing with higher accuracy by arbitrarily changing the number of coefficients of the estimated transmission path according to the condition of the transmission path. However, in order to perform equalization processing with high accuracy, the Viterbi decoder needs to be versatile and be able to support any arbitrary number of coefficients of the estimated transmission path.
Especially, in the field of mobile communications adopting the Viterbi decoding method, battery is used as a power source to improve the portability of the communication terminal apparatus, and so reducing power consumption is a material requirement.
For this reason, with conventional Viterbi decoders, dedicated hardware has been used to perform routine processing such as the calculation of branch metric or path metric that does not depend on the constraint length or suchlike for reduced power consumption. In addition, software has been used to perform processing whose processing flow is supposed to change according to constraint length such as coding from path select signal or maximum likelihood decision (for example, see Unexamined Japanese Patent Application Publication No. HEI11-74800).
By the way, in the field of mobile communications, there is demand for expansion of continuous call time of the communication terminal apparatus and reduction of battery capacity for improved portability. It is therefore desirable to provide a Viterbi that supports any arbitrary constraint length and any arbitrary number of coefficients of the estimated transmission path in dedicated hardware configuration requiring little power consumption, to realize a communication terminal apparatus requiring little power consumption, such as described above.
However, with conventional Viterbi decoders, as mentioned earlier, software is used for complex processing; therefore, the problem is that it requires large amount of power and is difficult to fulfill the above-mentioned requirement.

Matsushita Electric Industrial Co., Ltd.


A thermally powered change over diffuser for controlling the flow orientation of air discharged from a ceiling mounted duct outlet includes a pair of vanes pivotably mounted on a platform for scissor-wise movement between an open and a closed position, and a thermally responsive actuator. Discharge of cooled air from the duct causes the actuator to move the vanes together into the closed position, blocking the center of the flow path, and forcing the discharge air to exit in a substantially horizontal orientation. Discharge of heated air causes the actuator to move the vanes apart, into the open position, allowing warm air to flow vertically downwardly into a building space.

1. Field of the Invention
This invention relates to air diffusers and, more particularly, to air diffusers having arrangements for selectively controlling air flow based on thermal characteristics.
2. Description of Related Art
The use of air distribution units or diffusers as part of a heating, ventilating and air conditioning (HVAC) system is relatively well known. Such systems often include an air distribution system comprising a network of air ducts which supply heated or cooled air to various spacial areas in a building ventilated by the HVAC system. The air is discharged from the ducts into the ventilated areas by a series of air outlets. Typically, a diffuser is provided at or near the air outlet to control the flow of air entering the ventilated areas, and to provide an even distribution of air to a desired area without undue noise or uncomfortable drafts to disturb the occupants. The diffuser generally employs one or more vanes or deflectors to direct the discharge air flow in the desired orientation.
It is well known that the most effective manner of distributing air from diffusers during cooling is to direct the air in a horizontal flow across the ceiling of the room by employing what is known in the industry as the "Coanda effect." A stream of air discharged from a diffuser at an angle less than approximately 35 to 40 degrees with respect to the ceiling will tend to create a partial vacuum and cause the air stream to remain in contact with or hug the ceiling as a result of the Coanda effect. Cool air, therefore, can be distributed over a substantial area of the ceiling by employing the Coanda effect before the cool air begins to "sink down" into the room to cool the entire volume of the room.
In contrast, the best efficiency in connection with the distribution of hot air from ceiling mounted diffusers is for the air to be discharged in a generally vertically oriented stream. The vertical flow component overcomes the natural buoyancy of the heated discharge air to serve the lower strata of the room with heated air and to thereby achieve a proper mixing of the heated air with the room air. Because the discharged air flows through the occupied space before mixing is complete, drafts may be directed at the occupants. However, most people do not perceive warm drafts as uncomfortable.
In many HVAC applications, the same duct outlet may selectively discharge either heated or cooled air during different times of the day. For instance, thermostats are typically set back to 65.degree. F. or lower during the middle of the night. In the morning, most of the duct outlets will be discharging heated air to bring the air in the building up to its desired daytime temperature setting. As the day progresses, interior heat loads from people, lighting and computers may require that cooled air be directed to the interior of the building. Also, a southern exposure of the building will likely experience a solar warming load which must be overcome with cooled air directed to that part of the building. Particularly in the Spring and Fall, all areas of the building may require heated air in the morning and cooled air during the middle of the day.
While it is desireable to change the orientation of the air exiting the duct outlet, it is inconvenient to manually adjust a diffuser several times during the course of the day. Further, some buildings, such as banks and shopping malls, have their duct outlets located in high ceilings. Even infrequent adjustments of a manual diffuser is inconvenient in such locations. To address these problems, diffuser or air distribution units have been previously developed which automatically adjust the air distribution from a diffuser. Typically these systems employ some form of control system to sense the temperature of the discharge air and to control motorized adjustable vanes in the diffusers to adjust the air flow.
Several diffusers or air distribution units have been developed which incorporate the concept of a non-motorized, thermally responsive element to adjust the air distribution. For instance, in Kline et al., U.S. Pat. No. 4,515,069 issued May 7, 1985, a thermally responsive actuator rotates a blade assembly so that when warm air is flowing through the duct, a hot blade directs air primarily downward. When cold air is flowing through the duct, a separate cold blade directs the air primarily across the ceiling. The blades in Kline et al. comprise generally vertically oriented, opposite sides of a diamond-shaped box. By changing the orientation of the box in a duct, either the hot or cold blade may be presented to the air flow. A path formed between the selected blade and an opposing wall of the duct directs the air flow in the desired direction. The cold blade is angled more sharply off the vertical axis and interacts with a ramp wall formed in the duct to direct the air flow across the ceiling, while the hot blade is angled less sharply off the vertical axis to direct the air flow generally vertically downward.
The angle of the box in Kline et al. is controlled by a thermally responsive actuator or "pill" located in the flow path to sense the temperature of the air flow discharging the diffuser. The pill has a cavity filled with wax which expands upon melting at a predetermined temperature, thereby causing a piston to move outwardly from the cavity. At cooler temperatures, the wax solidifies and contracts. The piston is connected to the box by a linkage, so that movement of the piston into and out of the pill provides the motive force to operate the diffuser without the aid of additional motors and the like.
Two somewhat related patents, Herb, U.S. Pat. No. 4,535,932 issued Aug. 20, 1985, and Bryans, U.S. Pat. No. 4,625,629 issued Dec. 2, 1986, each employ a pill to operate a diffuser which selects between two discharge outlets depending upon the temperature of the discharge air. One discharge outlet directs the flow against a wall, and the other discharge outlet directs the flow into the interior of a room. The pill directs a baffle to selectively block one of the discharge outlets.
A separate concept for controlling the vertical and horizontal flow components of the discharge air is disclosed by Kennedy, U.S. Reissue Pat. No. 25,216 reissued Aug. 7, 1962. Kennedy controls the vertical and horizontal flow components of the discharge stream by selectively obstructing the central flow path of the air exiting the diffuser. With the central flow path blocked, the discharge flow is substantially horizontal. With the central flow path unobstructed, the discharge flow is substantially vertical.
The Kennedy diffuser comprises a perforated deflector of smaller area than, and in a substantially parallel orientation to, a perforated duct outlet face plate. The position of the deflector is controlled by a bellows which expands and contracts in response to the temperature of the air passing through the duct. In the warm air position, the perforations in the deflector and face plate are in register and allow air to pass through the center of the face plate. In the cold air position, the perforations and the deflector and face plate are out of register, preventing air from passing through the center of the face plate and forcing the air to exit the face plate with a more horizontal orientation. By blocking the air passageways, the deflector of Kennedy restricts the volume of air passing through the face plate when it is in the cold position.
Due to the large number of diffuser outlets in any given building, it is desirable that each be relatively simple and inexpensive. If adjustable diffuser outlets are used, it is desireable that each be quick and easy to adjust to accommodate variable air discharge temperatures. Automatically adjustable diffusers effectively address the latter requirement. However, many of the prior art automatic temperature controlled diffusers are unnecessarily complicated, employing sophisticated control systems and motorized diffuser elements to automatically select the appropriate flow pattern for a given temperature of discharge air.
An additional limitation of many prior art devices is the reduction of the area of the duct outlet when adjusted to discharge cooled air, thus reducing the volume of air discharging the diffuser. This has several disadvantages. For example, cooled air discharge temperatures are typically much closer to the desired building temperature than heated air discharge temperatures. Obtaining a given amount of cooling in a building space therefore requires proportionally more discharge air volume than an energy equivalent amount of heating in the same space. Reducing the area of the diffuser when discharging cooled air reduces the volume of discharge air precisely when an increased volume is desired.
Another instance where it is undesirable to reduce the volume of discharge air through individual diffusers is when using a variable air volume (VAV) control system. VAV systems employ dampers in the ductwork to direct a varying volume of air to a particular building space so as to achieve a desired air temperature in that space. An air diffuser which further restricts the volume of air entering the space makes control of the VAV system more difficult. For example, the air flow across a restricted duct outlet may create excessive noise.


A method and unit for transversely cutting cigarette portions or similar on a filter assembly machine, whereby a cigarette portion is fed transversely through a cutting station to intercept a rotary circular blade, which is maintained in a work position by an arm mounted to oscillate about an axis parallel to the axis of rotation of the circular blade, so as to move the circular blade between the work position, a store for worn circular blades, and a store for new circular blades.

On a known filter assembly machine, first elongated members, each defined by a double cigarette portion, are each cut transversely by a first cutting unit into two single portions; the single portions are then parted axially, are separated by a double filter, and are connected to each other and to the filter by a gummed band to form a double cigarette, which is cut transversely at the filter by a second cutting unit into two single filter-tipped cigarettes.
At each cutting unit, the cigarette portions are supplied transversely (i.e. in a direction perpendicular to their longitudinal axis) by a conveyor drum fitted with a circular blade rotating at high speed. To ensure a clean cut at all times, each cutting unit is fitted with a sharpening device, e.g. of the type described in U.S. Pat. No. 4,497,143-A1, for maintaining a keen blade edge. In view of the high output speeds of modern filter assembly machines (as many as 20,000 cigarettes a minute), continual sharpening subjects the circular blades of the cutting units to severe wear, thus requiring frequent replacement. In particular, the circular blade of the first cutting unit wears out faster than that of the second, by cutting the cigarette portions at the tobacco, whereas the circular blade of the second cutting unit cuts the cigarette portions at the filter material, which on average is softer and more homogeneous than tobacco.
In a high-speed, last-generation filter assembly machine capable of producing up to 20,000 cigarettes a minute, the circular blade of the first cutting unit must be changed at the end of each shift, i.e. every 8 operating hours. And since this calls for skilled labour and involves a certain amount of downtime (5-10 minutes), the frequency with which the circular blade of the first cutting unit must be changed obviously increases cost, in terms of both labour and downtime production loss.

Method and unit for transversely cutting cigarette portions or similar on a filter assembly machine