Provided is an image sensor device. The image sensor device includes a substrate having a front side and a back side. The image sensor includes first and second radiation-detection devices that are disposed in the substrate. The first and second radiation-detection devices are operable to detect radiation waves that enter the substrate through the back side. The image sensor also includes an anti-reflective coating (ARC) layer. The ARC layer is disposed over the back side of the substrate. The ARC layer has first and second ridges that are disposed over the first and second radiation-detection devices, respectively. The first and second ridges each have a first refractive index value. The first and second ridges are separated by a substance having a second refractive index value that is less than the first refractive index value.

Semiconductor image sensors are used to sense radiation such as light. Complementary metal-oxide-semiconductor (CMOS) image sensors (CIS) and charge-coupled device (CCD) sensors are widely used in various applications such as digital still camera or mobile phone camera applications. These devices utilize an array of pixels in a substrate, including photodiodes and transistors, that can absorb radiation projected toward the substrate and convert the sensed radiation into electrical signals.
A back side illuminated (BSI) image sensor device is one type of image sensor device. Some existing BSI image sensor fabrication processes suffer from high levels of optical cross-talk noise. Optical cross-talk noise degrades the performance of the BSI image sensor devices and is therefore undesirable. Other existing BSI image sensor fabrication processes may have somewhat acceptable optical cross-talk noise, but may result in low levels of quantum efficiency instead. A low quantum efficiency is correlated to a low signal-to-noise ratio of the BSI image sensor devices. The low-signal-to-noise ratio manifests itself as poor sensitivity for the BSI image sensor devices, which is also undesirable.
Therefore, while existing methods of fabricating BSI image sensor devices have been generally adequate for their intended purposes, they have not been entirely satisfactory in every aspect.

Ridge structure for back side illuminated image sensor

Taiwan Semiconductor Manufacturing Company, Ltd.


Systems, methods, and devices are provided to generate a stable supply of electrical power in a drill string. In one example, a downhole turbine generator includes a turbine, a speed governor, and an alternator. The turbine may transform hydraulic power of a first fluid medium into rotational power of a rotating shaft. The speed governor may reduce the rotational power of the rotating shaft in a variable amount that depends on the speed of the rotating shaft. Specifically, weighted arms may shear a second fluid medium more when the speed is higher and less when the speed is lower. The shearing of the second fluid medium may generate a countervailing torque on the rotating shaft to reduce the rotational power of the rotating shaft. The alternator then may produce a generally stable supply of electrical power from the rotational power of the rotating shaft.

This disclosure relates to converting the hydraulic power of drilling fluid moving through a drill string into a stable supply of electrical power, despite changes in drilling fluid flow rate.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present techniques, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
A drill bit attached to a long string of drill pipe, generally referred to as the drill string, may be used to drill a borehole for an oil and/or gas well. In addition to the drill bit, the drill string may also include a variety of downhole tools to measure or log properties of the surrounding rock formation or the conditions in the borehole. These tools often require power to operate. To generate this power, a turbine generator may convert hydraulic power of drilling fluid moving through the drill string.
Specifically, in the drilling process, drilling fluid is pumped down into the drill string to mechanically power the rotation of the drill bit and to help remove rock cuttings out of the borehole. The drilling fluid may pass over one or more turbines of a turbine generator to transform hydraulic power into rotational mechanical power. The rotational mechanical power may be transformed by an alternator into electrical power.
While the amount of electrical power provided by the turbine generator generally depends on the flow rate of the drilling fluid, the electrically powered tools of the drill string may operate within a range of possible input voltages and currents. Various systems have been developed to maintain the reliability of these electronic components as the flow rate of the drilling fluid changes. These systems, however, have many disadvantages. For example, a gearbox may transform the input rotation speed of a rotating shaft into a higher or lower rotation speed to enter the alternator of the turbine generator. Still, such a gearbox may require substantial maintenance and may increase the complexity of the downhole turbine generator system. Likewise, a fluid braking mechanism that is external to the turbine generator also has been developed. Such an external fluid braking mechanism may effectively prevent some excessive rotation speeds of the rotating shaft of the turbine generator. The external fluid braking mechanism may be dependent on characteristics of the drilling fluid, however, which may vary from drilling operation to drilling operation.

Turbine speed control system for downhole tool


A weighing scale having a display and processor for determining and identifying the optimal position coordinates for a load placed on the weighing scale includes a platform and a plurality of support assemblies, each containing a load cell for receiving the weight of the load. The display includes a meter or other graphical display that identifies position coordinates along with the determined numerical weight. Individual outputs from each of the plurality (e.g. 4) of load cells are received by a processor configured to compute x,y vector coordinates associated with the weight parameters for each load cell. The determined current or actual load position relative to an optimal position is calculated and displayed along with the weight.

There are many different types of electronic weighing scales in use today. One popular type of electronic weighing scale is constructed with a platform for receiving the load to be weighed and a set of levers, pivots, flexures, and torque tubes to mechanically combine the forces applied to the platform by the load, thereby enabling the measurement of these forces with a single electronic load cell, which operates as a force transducer. The load cell is typically constructed with a mechanically-deformable sensor plate with one or more sensor elements bonded thereto. When a load is applied to the load cell, the sensor plate mechanically bends and the sensor elements bonded thereto produce an electrical output signal, the magnitude of which is commensurate with the load applied to the load cell.
Another popular type of electronic weighing scale is constructed with a platform for receiving the load to be weighed, and a plurality of electronic load cells disposed at the corners of the platform, or more or less evenly spaced along the periphery or marginal periphery of the platform, for supporting the platform. Each of the load cells produces an electrical output signal indicative of the load sensed thereby. The electrical output signals of the load cells are averaged by processing circuitry associated with the scale to enable the load to be measured over a large area of the platform.
One problem associated with the multi-load cell scale described immediately above is that when the load is unevenly positioned on the platform, the load or force sensed by each of the load cells is not the same, with a disproportionate amount of the load or force being sensed by certain ones of the load cells. Consequently, the associated processing circuitry arrives at a weight calculation that is offset from the load's "true weight" determined when the load is centrally or optimally positioned on the scale.
Accordingly, a weighing scale is needed, which is capable of determining the position of a load being weighed thereon, and displaying the load's position relative to an optimal weighing position, so that the load can be repositioned to the optimal weighing position.

Weighing scale adapted for allowing a user to find an optical weighing position on the scale


Sprinkler guards to protect fire protection sprinklers in their installed and operative positions. A fire protection sprinkler guard includes a structure with a hinged arrangement to flexibly receive a fire protection sprinkler. A latch connection operates in combination with the hinge of the guard to form a rigid cage structure to shield and protect the sprinkler.

Generally, automatic fire protection sprinklers include a frame for connection to a supply pipe of firefighting fluid and a deflection member coupled to the frame for distribution of the fluid to address a fire. The frame includes a formed body having an internal passageway with a fluid inlet for receipt of the fluid and a fluid outlet defining a discharge orifice from which the fluid is discharged. Externally formed about the sprinkler body proximate the outlet is a boss or enlarged formation for engagement by an installation tool such as a wrench to facilitate sprinkler installation. In an automatic sprinkler, the fluid discharge is automatically controlled by operation of a thermally responsive trigger or actuator that maintains a fluid tight seal at the discharge orifice by, for example, exertion of pressure on a sealing assembly disposed within the outlet. When the temperature surrounding the sprinkler is elevated within a range of the nominal temperature rating of the trigger, the trigger operates thereby permitting ejection and release of the sealing assembly and the discharge of fluid through the discharge orifice. The discharged fluid impacts the fluid deflection member and is distributed in a designed spray pattern and density in order to effectively address a fire and wet the surrounding area. Several factors can influence the water distribution patterns of a sprinkler including, for example, the installation orientation and the geometry of the fluid deflection member, the distance between the deflection member and the discharge orifice, and/or the shape of the sprinkler frame to which the deflection member is coupled. Accordingly, the fluid control, distribution and performance of an automatic sprinkler is dependent upon the integrity of the sprinkler assembly and its individual components.
Automatic sprinklers are installed in a variety of environments which can expose the sprinkler to accidental impact. For example, storage type automatic sprinklers can be installed in a storage warehouse beneath the warehouse ceiling and above the storage area and commodities to be protected. In the storage environment, stored commodities are stacked and moved by operating personnel or material handling equipment such as forklifts. The movement of material or mechanical equipment proximate to an installed automatic sprinkler exposes the sprinkler to possible accidental impact and damage. If the trigger of the sprinkler is damaged, water may discharge from the sprinkler; or if the deflector or frame is damaged, the sprinkler may not distribute fluid in the proper pattern.
It is well known to use a sprinkler guard to protect an installed sprinkler. Generally, the sprinkler guard includes a caged enclosure with one open-ended base. The guard is installed by sliding the guard over the sprinkler through the base so that the sprinkler is coaxially centered within the cage. The guard is affixed to the sprinkler by securing the open-ended base about the sprinkler body against the enlarged boss of the sprinkler body. Sprinkler guards are configured for protecting sprinklers installed in an upright orientation, in which fluid is discharged from the sprinkler body toward the ceiling and then redirected downward by the fluid deflection member toward the protection area or a pendent orientation. Sprinkler guards are also configured for protecting sprinklers installed in a pendent orientation, in which fluid is discharged downward to impact the fluid deflection member for distribution below the sprinkler over the protection area. In the case of suppression type sprinklers such as, for example, Early Suppression Fast Response (ESFR) fire protection sprinklers, a portion of the spray pattern is directed or thrusted axially downward below the sprinkler toward the area being protected. Illustrative examples of these known sprinkler guards are shown and described in U.S. Pat. Nos. 3,797,746; 5,632,339; and 5,893,418. Examples of commercially available sprinkler guards are shown and described in technical data publication TFP784: Model EG-25 Sprinkler Guard For Model ESFR-25 Pendent Sprinkler (December 2017) from Tyco Fire Products, LP and technical data publication Form F_012798: Sprinkler Guards (Oct. 11, 2018, Rev. 16.1) from Viking Corp.
Although these caged enclosures can protect a sprinkler, a design concern remains in ensuring that the cage structure itself does not interfere with or inhibit the fluid distribution performance of the sprinkler. This can be of particular concern where the cage structure or portion thereof is in the spray path directly below or proximate the sprinkler fluid deflection member. Accordingly, there remains a need for sprinkler guard structures that provide sufficient protection to a sprinkler while minimizing or eliminating interference with the spray pattern of the sprinkler. In addition, some of these known sprinkler guards present an installation complexity. More specifically, due to the single open end of the guard through which the sprinkler is inserted, there is limited flexibility when installing the guard about the sprinkler. This can be difficult when working around the surrounding pipe. In addition, some of these known guards use a sliding clip or ring to secure the guard about the sprinkler and require a specific installation tool which can add to the complexity in affixing the sprinkler guard to the sprinkler. Other known sprinkler guards, as seen for example in U.S. Pat. No. 1,469,336 use a hinged base at the open end of a wire sprinkler guard to secure the guard to the sprinkler body. Although the hinged base can swing open and closed about the sprinkler body, locating the sprinkler centrally within the guard still requires insertion of the sprinkler through the open end of the wire guard. Accordingly, there remains a need for a sprinkler guard that provides for a simplified and flexible manner of installation.

Minimax Viking Research & Development GmbH


A combustor swirler for a gas turbine engine and method of manufacturing by metal injection molding an inner component and an outer cylindrical component. Indentations are molded in one of the inner and outer components and sealed by the engagement of the components together to form a series of fluid flow passages. The inner and outer components are molded with interlocking features for ensuring proper alignment of the components during assembly.

Gas turbine engine combustor air swirlers are exposed to a hot, corrosive environment. It is therefore necessary that they be fabricated of special high temperature alloys. Conventionally employed swirler manufacturing techniques include casting and/or milling combined with subsequent machining steps such as drilling and deburring. Due to the aerodynamic function of the component, care is required to ensure a suitable air flow is produced through the device. However, the special materials employed are not easily cast nor machined. A major disadvantage of casting lies in the difficulty of attaining the close tolerances required for the type of metallic seals involved.
Still further, most swirlers include critical guide air metering holes that are typically drilled one by one; thus, entailing a lengthy time consuming process that is expensive. Also, substantial effort is involved in deburring the holes which further increases costs. Not only does manual finishing considerably raise costs and require great precision to complete, but the result is variable due to its manual nature. It can be concluded that conventional machining, drilling and finishing operations for manufacturing combustor swirlers are time and cost ineffective. Consequently, the swirlers are undesirably expensive to manufacture by conventional means. Therefore, opportunities for cost-reduction exist.

Method of manufacturing a metal injection moulded combustor swirler


A support arrangement for supporting a flexible, water-containing mold of intricate configuration in a tank having supporting sides and containing a chilled liquid, such that an item of crystal clear ice can be created in the flexible mold. The flexible mold has an upper, support portion and a lower, principal portion, and also has interior surfaces possessing a distinctive degree of roughness. The support arrangement involves elongate support means for operatively engaging the upper portion of the mold, with the elongate support means being of a length sufficient to span between the supporting sides of the tank such that the mold can be supported with a selected extent of the principal portion of the mold immersed below the surface of the chilled liquid. Circulation of the water in the mold is brought about so that the interior sides of the mold will be swept, thus preventing the formation of cloudy ice. The arrangement for causing circulation of the water in the mold may involve a gas supply utilized for supplying controlled amounts of gas to a lower interior portion of the mold so that suitable amounts of gas can be caused to rise up through the water in the mold and prevent the formation of cloudy ice. Other arrangements for causing circulation of the water in the mold may include power driven rotatable means disposed in the mold.

This invention relates to a method and novel apparatus for forming ice objects of intricate configuration, and has particular application in the formation of decorative ice statuary and the like to be utilized at banquets, wedding receptions and similar festive occasions to decorate the tables in a unique and impressive manner. Such ice statuary also has application in the decoration of windows of restaurants and the like.
Ice sculptures have long been appreciated for their aesthetic appearance, due primarily to the smoothly flowing and/or artistic surfaces of the ice and to the clarity of the ice and its ability to transmit light therethrough. Ice sculptures have often been used as distinctive decorations for banquets, celebrations, and many other such business or joyous occasions. When fashioned as bowls, the ice sculptures can also provide a desired cooling effect upon the punch or other liquid contained in the bowl.
In the past, ice sculptures involving unusual shapes have generally been fabricated from large blocks of clear ice, using special tools to chip, form, and smooth the ice. Chain saws are frequently used to form large ice sculptures. Such techniques involve a great deal of the mass of the original block of ice being wasted. Moreover, the labor involved in forming the ice sculpture has resulted in high cost of the sculptures. In many localities, artists of sufficient skill to carve attractive ice statuary are simply not available.
Some ice statuary has earlier been created by the use of molds formed from metal or the like, with punch bowls and other cavity-containing objects being typical. Such metal molds are filled with water and then immersed to an appropriate extent in a cooling medium such as a tank of brine or glycol equipped with refrigeration coils. Such immersion is usually within an inch or two from the top of the mold. To assure clarity of the ice, compressed air is inserted near the bottom of each mold during the freezing process. After ice has formed to a desired thickness, the mold is removed from the tank and then maintained in an inverted position until a degree of melting takes place and the ice object drops out of the mold.
One distinct advantage of the use of molds of this type is that these improved techniques have permitted the inclusion of various decorative elements, such as flowers, bright objects, letters, paper letters, or other decorative or visual indicia, within the structure of the ice bowl.
It is quite difficult by the use of metal molds, however, to create ice objects of intricate shape, and any "undercut" created in the mold would make removal of the ice object from the mold nearly impossible.
Exemplary of the prior art teachings is U.S. Pat. No. 2,545,592 to Sherbloom wherein is disclosed a method of forming ice molded figures by the utilization of a split mold adapted to be immersed in a can that is subsequently placed in a refrigerated tank of brine. However, the apparatus necessary for the practice of prior art methods has been relatively cumbersome and has precluded the adoption of these methods by relatively small restaurants, hotels and the like.
A method of molding ice sculptures is described in U.S. Pat. No. 4,206,899 to Whitehead, with this method involving supporting a water-filled flexible mold in an inverted position within a rectangular outer box. Because of the hydrostatic pressure of the water, especially with large sculptures, the flexible mold must be of sufficiently thick wall structure to prevent distortion. In addition, this method uses a walk-in freezer or the like, which causes a freezing of the mold from all sides including the top of the water level. This in turn causes the ice to "crust over" which traps in all the air on the inside of the mold, causing cloudy and cracked ice.
The necessary thick-walled flexible molds are expensive to make and difficult to peel off the ice sculpture. It is also found that sculptures made by the method and apparatus of U.S. Pat. No. 4,206,899 contain cracks which detract from the appearance and structural integrity of the sculpture. Such sculptures are typically quite cloudy due to lack of circulation, and in addition, the mold must be placed in a freezer.
Whitehead utilizes a mold in its base through which support wires are inserted. The mold is inverted, base up, within a box slightly larger than the mold with the wires engaging the open top of the box and supporting the mold. After the mold is filled with water and frozen, it is removed from the box and the mold is stripped from the frozen sculpture.
The single part mold used by Whitehead is of such a nature as to be restricted to sculptures which taper more or less uniformly from top to bottom so that the mold can be removed from the finished sculpture. The Whitehead mold could not, for example, be used to mold an ice sculpture having relatively small top and bottom portions and an enlarged central portion. Furthermore, the Whitehead mold can only be used to make relatively small ice sculptures due to the nature of the flexible material Whitehead uses for his molds. If his molds were larger, the weight of the water would expand the bottom of the mold.
Although it has previously been known to create crystal clear ice by the use of reusable metal molds, in order to prevent cloudiness of the resulting ice, it has been common practice to circulate the water in the mold to remove air bubbles. Such circulation is typically brought about by an aeration arrangement. Without sufficient circulation, crystal clear ice simply cannot be obtained.
The Reynolds U.S. Pat. No. 1,476,220 entitled "Method of and Means for Agitating Water in Ice Making Apparatus" teaches the use of an ice or brine tank 10 within which are placed ice cans 11 containing the fresh water to be frozen into ordinary ice blocks. This patentee utilizes what he calls an agitator pipe 18 in each ice can 11, for the introduction of air supplied from a blower 12. Reynolds explains that as a result of agitating the water, the impurities will collect. When the water has changed to ice, except for a small core in the middle of the can, this water with the impurities may be removed, and distilled water substituted.
It is obvious that Reynolds discloses nothing pertaining to the creation of ice objects of intricate configuration by the use of flexible molds, for he is entirely concerned with the creation of ordinary ice blocks, presumably for home or commercial use.
It is obvious that when using reusable metal molds, one end of the mold must be larger than the other end, and no "undercuts" may be utilized. Otherwise, it would not be possible to remove the completed ice structure without destroying the mold or else melting substantial portions of the ice object.
An alternative to the use of metal molds has been the use of hard plastic molds, with in many instances such molds being destroyed when the ice sculpture is to be removed. However, this is obviously an expensive approach.
In the Sherbloom U.S. Pat. No. 2,545,592 it was taught that two-part molds can be utilized, which molds are secured together and then immersed in brine or other cold liquid in order to bring about the freezing of the contents of the mold. However, nothing is said in Sherbloom about providing aeration, so the ice objects resulting from the use of Sherbloom's technique will be of cloudy ice rather than crystal clear ice. Even if Sherbloom created the parts of the mold that come together, this would not allow sufficient circulation, causing dead spots in the mold where the water is stagnant, thus creating cloudy pockets of ice.
Another Sherbloom patent is U.S. Pat. No. 2,939,299, which also utilizes two-part molds of hard material. Sherbloom obviously discovered that he could not create objects of crystal clear ice without aeration, so in Column 4 of this more recent patent, Sherbloom describes how his mold sections are aerated continuously through air hoses 48 during the freezing process to produce a frozen object characterized by the clarity of the ice from which it is molded. How Sherbloom prevents his air line from freezing in place is not described, however.
It is to be noted from the drawings of the Sherbloom U.S. Pat. No. 2,939,299 that the objects he creates are comparatively flat. In other words, two dimensional objects can be created, but not three dimensional objects. Three dimensional objects have deep crevices. Sherbloom utilizes hard, non-flexible molds, which simply cannot have three dimensional, lifelike undercuts.
With reference to the Whitehead U.S. Pat. No. 4,206,899, it will be noted that this patentee utilizes molds fabricated from form-retaining, flexible, resilient plastic material. However, from the material he utilizes for his molds, it is apparent that if the molds are too thick, it will be exceedingly difficult to remove the completed ice sculpture from the mold, but on the other hand, if the material from which the mold is made does not have enough character or thickness, the object created in the mold will take on a "bulged out" appearance and not be faithful to the intended configuration.
It is significant to also note with respect to the Whitehead patent that he may utilize the environment of a walk-in freezer for bringing about the freezing of the water in the mold, but in such instance, the icing over of the water in the top of the mold will prevent any effective aeration of the water in the mold. As a result, cloudy ice will predictably result from the utilization of this Whitehead technique.
With reference to the DeGaynor U.S. Pat. No. 4,550,575 entitled "Ice Bowl Freezing Apparatus," it is obvious that no intricate shapes are possible, for when using metal molds, the ice object would be impossible to remove should any "undercut" be present. DeGaynor recognizes the advantage of providing air circulation, but it would be impossible utilizing DeGaynor's technique to create any ice object of intricate configuration, such as statuary or the like.
With reference to the Wu U.S. Pat. No. 4,562,991, it will be noted that although Wu employs a reusable ice mold that allegedly produces intricate ice objects, it is obvious from FIGS. 1 and 6 that the fowl depicted in these figures is of "chunky" and non-intricate configuration. Also, because no aeration or circulation is mentioned, Wu will not be able to create crystal clear objects by the practice of his method.
The Noel U.S. Pat. No. 4,669,271 is concerned with multi-part molds, but he utilizes his molds in a walk-in freezer. For this reason, the upper surface of the water in the mold will ice over, thus trapping inside the mold, any air bubbles that may be present, thus resulting in the formation of a cloudy ice object. Most importantly, no circulation is possible.
The Parmacek et al U.S. Pat. No. 4,739,963 is concerned with plastic molds, with his improvement being a hollow core formed in the base of the mold to allow for expansion in the mold when it changes phase into ice. Because of this arrangement, these patentees maintain that they reduce stress and cracking in the finished ice form. The Parmacek et al patent process allows one-time only use of the mold, with the mold being destroyed after use.
However, nothing is said in the Parmacek et al patent about the use of aeration or circulation, so crystal clear ice will not result from a practice of that method.
The Tu U.S. Pat. No. 4,807,844 utilizes a mold of elastomeric material, but he places his mold in a walk-in freezer and says nothing about aeration. Inasmuch as the placement of the mold in a walk-in freezer necessarily brings about an icing over of the water in the top of the mold, any circulation induced by the utilization of compressed air or any other method would result in the entrapment of the bubbles in the ice. Tu's method will definitely not result in the creation of crystal clear ice.

Method and apparatus producing clear ice objects utilizing flexible molds having internal roughness


A gate latch for selectively securing a pivoting gate to a stationary member and selectively retaining the gate in a closed position. The gate latch is formed of a hollow tube and is received on a vertical component of the gate. The hollow tube includes an elongate opening with a first width section and a second width section. The second width section is radially wider than the first width section. A horizontal component of the gate extends through the tube elongate opening and acts as a stop member for limiting both longitudinal and radial movement of the tube. A U-shaped bar is affixed to the hollow tube and forms two arms extending therefrom adapted for engaging the stationary member. The gate is retained closed by placing the stop member in the first width section and effectively preventing radial movement of the gate latch. The gate is selectively opened and closed by longitudinally sliding the hollow tube and locating the stop member in the second wider section of the tube opening and, thus, allowing greater radial movement of the tube and, also allowing the selective disengagement and engagement of the stationary member from inbetween the arms.

Over the years, various gate latch mechanisms have been devised for the purpose of selectively closing and opening a gate. Examples of such mechanisms are shown in Beatty, U.S. Pat. No. 1,032,371; Reymann, U.S. patent No. 2,661,971; McCormack et al., U.S. Pat. No. 3,918,753; Kerr, U.S. Pat. No. 4,226,450; and, Norton, U.S. Pat. No. 4,512,105. All of these gate latch mechanisms function and accomplish the end result. However, they tend to be complex and generally time consuming and costly to manufacture. For example, Kerr, U.S. Pat. No. 4,226,450 and McCormack et al., U.S. Pat. No. 3,918,753 disclose gate latches which are functional but which incorporate many different components and which substantially increase production costs and, thus, the overall cost to the consumer. In addition, such gate latches have a greater tendency to fail due to the complexity and large number of components.
With respect to some prior gate latches, it is also possible to accidentally bump and/or otherwise inadvertently open the gate. As can be appreciated, this is undesirable, especially for example, with respect to gates on platforms which may be used for lifting people and/or other objects. It is also undesirable when the gate is used for holding back farm animals.
Accordingly, a need exists for a gate latch that positively secures a pivoting gate to a stationary member and which will not inadvertently easily be disengaged. In addition, a need exists for a gate latch which is generally easy and inexpensive to manufacture and which is reliable and long lasting.


Provided are a reflective mask blank and a reflective mask which are capable of improving the contrast for inspection light having a wavelength of 200 nm or less in an inspection, capable of improving the contrast for exposure light in use of the mask, and capable of forming a high-resolution fine pattern. A reflective mask blank 10 includes a substrate 1, and a multilayer reflective film 2 adapted to reflect exposure light, a protective film 6 composed mainly of ruthenium (Ru) or its compound on the multilayer reflective film 2, and an absorber film 4 adapted to absorb the exposure light, which are formed in this order on the substrate. The absorber film 4 has a laminated structure including an uppermost layer 4b and a lower layer 4a. The uppermost layer 4b is formed of a material composed mainly of a nitride, an oxide, an oxynitride, a carbide, a carbonitride, or an oxycarbonitride of at least one or more elements selected from Si and Cr. A reflective mask 20 is obtained by forming a transfer pattern in the absorber film of the reflective mask blank.

In recent years, with higher integration of semiconductor devices, fine patterns exceeding the transfer limit of the photolithography technique have been required in the semiconductor industry. In view of this, the EUV lithography being an exposure technique using extreme ultraviolet (Extreme Ultra Violet: hereinafter referred to as EUV) light with a shorter wavelength is expected to be promising. Herein, the EUV light represents light in a wavelength band of the soft X-ray region or the vacuum ultraviolet region and, specifically, light having a wavelength of about 0.2 to 100 nm. As a mask for use in the EUV lithography, there is proposed an exposure reflective mask, for example, described in Patent Document 1 noted below.
This reflective mask has a multilayer reflective film formed on a substrate and adapted to reflect exposure light, a buffer film formed in a pattern on the multilayer reflective film, and further an absorber film formed in a pattern on the buffer film and adapted to absorb the exposure light. The buffer film is provided between the multilayer reflective film and the absorber film for the purpose of protecting the multilayer reflective film in pattern forming and correcting processes of the absorber film. The light incident on the reflective mask mounted in an exposure apparatus (pattern transfer apparatus) is absorbed at a portion where the absorber film is present, but is reflected by the multilayer reflective film at a portion where the absorber film is not present so that an optical image is transferred onto a semiconductor substrate through a reflective optical system.
Such a reflective mask is manufactured, for example, through the following processes.
(1) A predetermined resist pattern is formed on an upper surface of a reflective mask blank in which the multilayer reflective film, the buffer film, and the absorber film are formed in this order on the substrate and, using the resist pattern as an etching mask, a predetermined pattern is formed in the absorber film by dry etching.
(2) Herein, using inspection light, an inspection is performed to check whether or not the pattern is formed as designed in the absorber film. In this event, the inspection is carried out by detecting inspection light reflected by the absorber film and inspection light reflected by the buffer film which is exposed by the removal of the absorber film, thereby observing the contrast therebetween.
(3) If, as a result of the inspection, it is found out that the pattern of the absorber film has a white or black defect, correction of a pinhole or the like is carried out by FIB-assisted deposition or the like for the white defect, while, correction is carried out by removing an unnecessary portion by FIB irradiation or the like for the black defect portion.
(4) Then, using as an etching mask the absorber film formed with the above-mentioned pattern, the buffer film is removed by dry etching according to the absorber film pattern, thereby transferring the pattern to the buffer film.
(5) Finally, using inspection light, a final confirmation inspection of the formed pattern is performed. In this event, the inspection is carried out by detecting inspection light reflected by the absorber film and inspection light reflected by the multilayer reflective film which is exposed by the removal of the absorber film and the buffer film, thereby observing the contrast therebetween.

Reflective mask blank and method of manufacturing a reflective mask


Potable drinking water is a scarce resource in many parts of developing countries, especially rural areas. Due to limited financial means of these countries, low cost point-of-use systems are thought to be appropriate technology to treat water. Systems using solar ultraviolet (UV) radiation could be successful since many vulnerable countries are located where solar radiation is intense and abundant throughout the year. The goal of this disclosure is to develop a simple and low cost point-of-use solar UV reactor to disinfect water. In this disclosure wavelength-dependent microbial dose-response behavior was investigated using surrogates to pathogenic microbes. A solar radiation prediction method based on the SMARTS model was used to predict solar UV intensity as function of geographic location and time. A numerical modeling procedure using the discrete ordinate (DO) model and CFD software (FLUENT) was used to simulate UV dose (distribution) delivery to microorganisms. Then, the dose distribution was combined with the dose response behavior using a segregated flow model to predict microbial inactivation by the reactor. A prototype was produced and tested to validate the numerical modeling procedure. The inactivation results from the prototype were in agreement with numerical inactivation prediction. The modeling procedure permits parameters such as reactor dimensions and material properties to be varied to meet a treatment goal.

A large part of the world still lacks safe drinking water. The world health organization (WHO) estimates that roughly 1.1 billion people in developing countries do not have access to potable drinking water, and 2 million die every year due to drinking water-related diseases (WHO/UNICEF, 2006). Children are more vulnerable and every day the world loses roughly 3900 children below age 5 (WHO/UNICEF, 2004). A third of the people living in rural areas, slums and poor suburbs in developing countries use streams, ponds, rainwater from roofs, and poorly constructed wells that can be, contaminated with pathogens. The majority of contamination originates from human and animal fecal matter that, due to poor sanitation, ends up in streams and wells. These problems are acute in sub-Saharan Africa, and some countries in Oceania, eastern and southern Asia (Dejung et al., 2007; Gadgil, 1998). FIG. 1 shows world coverage of improved (conventional) drinking water systems; in Africa less than 50% of people have access to improved drinking water facilities. Forty two percent of the sub-Saharan African population use unimproved water sources, and are the largest population without access to improved drinking water sources, estimated to be around 528 million people, lives in South and East Asia (WHO/UNICEF, 2006).
There are six main categories of drinking water related diseases: —diarrhea; caused by some microbial pathogens, —ascaris, —dracunculiasis, —hookworm and other worms, —schistosomiasis, and —tracoma (Gadgil, 1998). These diseases can lead to disability, morbidity, and death. Also, chemical contamination, in particular arsenic and fluoride naturally present in some soils, is fairly common in developing countries. Lack of potable water is also one of the hindrances to economic development. Sickness in adults who are breadwinners affects the whole family in households. Diarrheal diseases in children reduce food absorption which in turn causes malnutrition, and impairs physical and mental development. Women in affected regions have to walk long distances to find potable water and spend time caring for sick children. Beside loss of life, another major consequence of lack of potable water is lost productivity due to sickness (Gadgil, 1998).
Solar disinfection debuted when Acra et al. (1984) observed inactivation of enteric bacteria due to solar radiation. Solar disinfection health benefits were emphasized when a study on Kenyan children under 5 years old found that children who drank water filled in PET plastic bottles exposed to sunlight for a day (SODIS: solar disinfection), showed a 16-24% reduction in incidence of all diarrhea episodes and a 86% reduction of cholera during an outbreak (Meierhofer, 2006). In 2006 a survey showed that 2 million people in poor communities in 20 countries use SODIS and as a result diarrhea incidence has been reduced by 30 to 70% (Meierhofer, 2006). This low cost technology, SODIS, consists of exposing a plastic bottle filled with water to sunlight of at least 500 W/m2 for 5 hours (Oates et al., 2003). SODIS has been demonstrated as a system applicable in regions between latitude 35° North and 35° South, with at least a six-hour exposure to get a 3-4 log10 (99.9-99.99%) reduction in E. coli, Vibrio cholera, Salmonella spp, Shigella spp, Rotavirus, Giardia and a 2-3 log10 (99-99.9%) reduction in Cryptosporidium spp. (Meierhofer, 2006).
Disinfection Using Ultraviolet Radiation
The fundamental behavior of UV radiation as a disinfectant has been examined in detail. Some biomolecules within microorganisms, such as nucleic acids and proteins, have high absorption in the UV region of the electromagnetic spectrum and may undergo (mutagenic) photochemical alterations when exposed to UV (Jagger, 1967). The most common form of UV-induced damage within nucleic acids is photodimerization of adjacent pyrimidine bases. Another form of UV induced damage, apart from mutagenic effects to DNA, is loss in activity in some cell proteins; proteins with high amounts of tryptophan, tyrosine, phenylalanine amino acids are prone to UV damage (Blatchley and Peel, 2001). It is believed that mutagenic effects prevent transcription and the cell cannot replicate. If a cell cannot multiply, it can no longer cause infection (EPA, 2006).
Solar UV Disinfection
The antimicrobial effect of solar UV depends on the spectrum of radiation reaching the Earth's surface. The "near UV" range (290-400 nm) represents wavelengths of solar radiation that can reach the Earth. Peak DNA absorbance generally lies between 250 and 260 nm. However, radiation in this wavelength range is not included in the solar UV spectrum at the Earth's surface because of absorbance by atmospheric constituents. In addition to photodimerization, it has also been suggested that the damage occurs at the cell's chromophores and their prosthetic groups, also called endogeneous photosensitizers (FAD, NAD, heme, quinons, porphyrins, Fe—S cores) (Dejung et al., 2007). These chromophores are known to absorb radiation in the near-UV and above 400 nm. The shift of chromophores to other excitation states releases some energy and due to absence of energy acceptors, absorbance of these photons can lead to conformational changes in the chromophores, thus causing a biological activity loss. On the other hand, oxygen can act as energy acceptor and generate radicals, also known as reactive oxygen species, which are capable of causing damage to the cell membrane (Dejung et al., 2007). Reactive oxygen species also damage DNA by strand breaks and base changes. Also, in the presence of solar UV, exogenous photosensitizers such as humic substances react with oxygen and generate highly reactive oxidants such as hydrogen peroxide (H2O2), singlet oxygen and superoxides, which may display antimicrobial behavior (Kehoe et al., 2004). Exposure of E. coli to near-UV radiation has also been linked to impairment of membrane transport and the catalase enzyme system, leading to inactivation (Vidal and Diaz, 2000).
Action Spectra
An action spectrum of a microorganism provides a quantitative measure of its relative response at different wavelengths. For polychromatic UV sources, it is important to know what wavelengths are involved in a given action and how much effect each wavelength induces compared to other wavelengths. The action spectrum can also be described as the reciprocal of the dose required for a given effect versus wavelength (Jagger, 1967). The reciprocal of the dose versus wavelength shows that wavelengths that require the lowest dose for a given effect are the most efficient. As an example, FIG. 2 shows the relative germicidal effectiveness for inactivating E. coli. FIG. 2 shows that to inactivate E. coli using wavelength in near UV, for example using 3000 Å (300 nanometers; nm), the dose required is roughly 10 times the dose required at around 2600 Å (260 nm), it jumps to 1000 times at around 3400 Å (340 nm) and 10000 times at 4000 Å (400 nm).
Microbial Cell Repair Mechanisms
Some microorganisms are equipped with DNA repair mechanisms to respond to UV damage. There are four main enzymatic repair mechanisms; one is the light-dependent repair mechanism and three are dark-repair mechanisms. Light-dependent repair reverses UV-induced damage for pyrimidine dimers with the help of photolyases (photoreactivating enzymes). These enzymes work in presence of UV and visible light (300-600 nm). Of the dark-repair mechanisms, the most commonly observed repair is nucleotide excision repair (NER) and is known to be slow. NER repair occurs on pyrimidine dimers and other lesions not caused by UV. Some E. coli cell proteins that participate in NER include DNA polymerase I, ligase, Uvr A, Uvr B, Uvr C and Uvr D. A second dark-repair process is known as ultraviolet excision repair. It occurs in only pyrimidine dimmers caused by UV radiation and is relatively faster than NER. The third dark-repair mechanism involves an enzyme known as glycosylase to repair pyrimidine dimers (Blatchley and Peel, 2001).
Solar Radiation
Solar radiation is electromagnetic energy that originates from the Sun. The outer layer surface of the Sun is made up of cooler gases which are strong energy absorbers. This layer has properties similar to a blackbody, with a temperature estimated to be around 5777 K. The energy absorbed and reemitted by the black body is the radiation that is emitted by the Sun. The Earth, which is 1.5*1011 m away of the Sun, receives roughly 1.5×1018 kW·h per year of solar radiation energy, or approximately 28,000 times the world energy consumption per year (Duffie and Beckman, 1991).
Due to eccentricity of the Earth's orbit around the Sun, the energy that is received at the outer edge of the Earth's atmosphere (also known as the solar constant) varies daily, with a yearly average energy of 1367 W/m2 at an average solar-earth distance of 93 million miles. This yearly variation solar constant variation is shown in FIG. 3.
Solar radiation received at the surface of Earth varies with latitude, longitude and ordinal date of the year. In addition, due to Earth's rotation, for an observer on Earth's surface the Sun sweeps an arc from sunrise in the morning to sunset in the evening with high energy at noon when the Sun is at zenith. The more you move away from the equator toward the South or North Pole, the more solar rays become inclined and have to travel a longer distance through Earth's atmosphere, and hence more attenuation they experience. The angle at which the solar rays strike a horizontal surface on Earth surface is called the incidence angle. Solar radiation also varies according to altitude and local climate. The spatial distribution of solar radiation is illustrated in FIG. 4. On this graph the world solar radiation distribution is expressed in Kw·h per square meter per year. The highest energy is located in regions near the tropics in regions depicted with dark red color and lowest as you approach the poles in regions marked with yellow color. Cloud cover is also important to attenuation of solar radiation. As an example, near the equator solar rays tend to be perpendicular to horizontal surfaces, but due to the presence of clouds formed by equatorial rain forests and movement of winds, solar radiation is often less intense than radiation observed in the deserts (e.g. Sahara and Kalahari) near the tropics in Africa (FIG. 4).
Solar Radiation Collection
Background on Solar Radiation Collection Technologies
Solar energy collectors are devices that collect, concentrate and transfer energy to a fluid or convert it to electric current. These collectors can be classified with respect to whether they are concentrating or non-concentrating. They can also be classified with respect to whether they are stationary or tracking. In the category of stationary collectors, two types of collectors are mostly used in solar energy: Flat plate collectors (FPC) and Stationary compound parabolic collectors (CPC).
In the category of tracking collectors, there are many geometries that are in use and among them the basic geometries include: Parabolic trough collector (PTC), Cylindrical trough collector (CTC), and Linear Fresnel reflector (LFR).
Types of Collectors
Flat Plate Collectors (FPC)
Flat plate collectors are more economical than most other collectors (Kalogirou, 2004). They are mostly used in low temperature fluid heating applications. In this device, pipes that carry the fluid run on a flat absorber (e.g. sheet metal) with insulation covers on sides and bottom, and glazing glass at the top (FIG. 2.7). For heating applications the absorber sheet metal is coated with a black color and the glass cover serves as a protection against convection and reradiation losses. The glass cover transmits short wavelength radiation from the sun but it is opaque to long-wave thermal radiation from the absorber plate. Flat plate collectors are mostly static and they are oriented toward the equator; oriented south in the northern hemisphere and oriented north in southern hemisphere (Kalogirou, 2004).
Compound Parabolic Concentrator (CPC)
The CPC is a unit of two parabolic sections facing each other. The non-tracking CPC was originally designed for solar thermal collection purposes: CPCs include a reflector system that directs solar radiation to the absorber without tracking the sun (independent on incidence angle). Using one or multiple internal reflections, the CPC allows collection of nearly 70% of global solar radiation without a tracking system. This system also is able to collect both diffuse and beam radiation. Diffuse radiation represents roughly 50% of total solar UV radiation (Vidal and Diaz, 2000). FIG. 5 shows the geometric characteristics of a CPC; it is made up two reflective side walls and a receiver pipe or plane is fixed at the bottom where those walls meet. The angle between the diagonals is the acceptance angle (θ). The acceptance angle is also defined as the angle through which all radiation with incidence angle smaller than acceptance angle strikes the absorber. The CPC takes the radiation received at the aperture area and concentrates it to a smaller collection area; the concentration ratio (C) is defined as following in Equation 2.1:C=a/a′=1/sin θ.  Equation 2.1Where a is aperture size, a′ is the receiver size, and θ is the acceptance half-angle.
The absorber area can have various configurations depending upon use; it can be a flat area or a tube as shown in FIG. 5. A CPC longitudinal axis can be oriented east-west or north-south. When it is oriented east-west, it can collect radiation along daily solar movement without tracking. The transversal axis is tilted to the south in northern hemisphere and tilted north in southern hemisphere with little seasonal adjustment. For stationary CPCs in this mode, the acceptance angle should cover declination of the Sun from summer to winter solstices (47° equivalent to 23.5° for each solstice). When the CPC longitudinal axis is oriented in the north-south direction, it should be tilted to track the Sun, such that the solar incidence angle remains within the acceptance angle.
Tracking Collectors
Almost all tracking collectors are also concentrators; a tracking system follows the Sun's movement in the sky. It should maintain its ability to track the Sun during intermittent cloud cover and clear sky, protect the collector against severe environmental conditions such as wind, overheating and alarm in case of failure. The most popular types of tracking concentrators are described below.
Parabolic Collector
A reflector of parabolic shape is mounted in the background of the evacuated pipe. The reflector is positioned in the direction of the Sun in such a way that the solar rays hit perpendicularly to the plane of the reflector and get reflected to a focal point or line. Most parabolic collectors, except compound parabolic collectors, require a Sun tracking system that allows it to rotate around an axis oriented north-south or east-west or both. This type can achieve very high concentration since a large area can be concentrated on a very small area.
Parabolic collectors can be categorized in two major types; parabolic trough and parabolic dish (circular). For a parabolic trough the energy is concentrated to a focal line while a parabolic dish directs collected radiation to a focal point. The size of the tube or collection point depends on the size of concentrated Sun's image and manufacturing tolerances of the collector. A parabolic trough with an axis facing north-south collects more solar energy than an east-west oriented system in summer, while east-west system collects more energy during winter. However, over a year, the energy collected is slightly higher for a system with a north-south orientation. Also, parabolic dishes have a double-axis tracking system (Kalogirou, 2004).
Linear Fresnel Reflector (LFR)
This collector is a composite of individual mirror strips which concentrate radiation on a fixed-point receiver. This system has an advantage in manufacturing as the reflecting strips are flat and do not require precision curving compared to parabolic collectors. In addition each strip can be maintained separately. The receiver is usually static and mirror strips require a tracking system to direct radiation to the receiver.
Collector Materials
Reflecting materials make it possible to deviate and concentrate solar radiation intensity by collecting solar rays on a certain area and transferring them to a smaller area. The ideal or maximum concentration gained equals the ratio of the two areas. The ideal concentration would correspond to a system that reflects, transmits and collects 100% of energy falling on the collector, and in reality such a system is not feasible, because of imperfections in manufacturing and wear and tear from UV (this will be discussed later in reflecting materials section). Transmitting materials are used for covers of the system and tubes, allowing radiation to be transmitted to the target fluid or the absorber.
The integrated solar reflectance at incidence angle θ (Rsol(θ)) is defined as (Equation 2.2) (Nostell, 2000).
                              Rsol                                (            θ            )                          =                                            ∫              λ1              λ2                                                                  R                                                  (                                      λ                    ,                    θ                                    )                                            *                              Ssol                                                  (                  λ                  )                                            *                                                                                ⅆ                λ                                                                        ∫              λl              λ2                                                                  Ssol                                                  (                  λ                  )                                            *                                                                                ⅆ                λ                                                                        Equation                                                  2.2            Where R(λ, θ) is the wavelength dependent reflectivity at angle θ, Ssol (λ) is the spectral solar irradiance and the limits on integration are the boundaries of UV wavelength. Similarly, the replacement of R by T allows calculation of the integrated solar transmittance (Equation 2.3) (Nostell, 2000).
                              Tsol                                (            θ            )                          =                                            ∫              λ1              λ2                                                                  T                                                  (                                      λ                    ,                    θ                                    )                                            *                              Ssol                                                  (                  λ                  )                                            *                                                                                ⅆ                λ                                                                        ∫              λl              λ2                                                                  Ssol                                                  (                  λ                  )                                            *                                                                                ⅆ                λ                                                                        Equation                                                  2.3            For reflectors a portion of energy received is lost through wavelength-dependent absorbance (Asol(θ)) (Equation 2.4). The integrated absorbance equals 1 minus integrated reflectance (Equation 2.5) (Nostell, 2000).
                              Asol                                (            θ            )                          =                                            ∫              λ1              λ2                                                                  (                                  1                  -                                      R                                                              (                                              λ                        ,                        θ                                            )                                                                      )                            *                              Ssol                                                  (                  λ                  )                                            *                                                                                ⅆ                λ                                                                        ∫              λl              λ2                                                                  Ssol                                                  (                  λ                  )                                            *                                                                                ⅆ                λ                                                                        Equation                                                  2.4                                          A                                (            λ            )                          =                  1          -                      R                                      (              λ              )                                                          Equation                                                  2.5            The total integrated reflectance (Equation 2.6) is equal to the sum at all incidence angles; in the equation below W (θ) is the angular weight function; the limits are angles of incidence which vary from 0° to 90°.
                    Rsol        =                                            ∫              0                              90                                °                                                                                Rsol                                                  (                  θ                  )                                            *                              W                                                  (                  θ                  )                                            *                                                                                ⅆ                θ                                                                        ∫              0                              90                                °                                                                                W                                                  (                  θ                  )                                            *                                                                                ⅆ                θ                                                                        Equation                                                  2.6            Similarly, by replacing R by T we get integrated transmittance. The sum of wavelength-dependent reflectance, transmittance and absorptivity equals 1 (Equation 2.7).R(λ)+T(λ)+A(λ)=1  Equation 2.7Reflecting MaterialsUV Reflecting Metal Sheets
Aluminum has been used for long time as a reflector of solar rays. Compared to other metal materials such as stainless steel and silver, aluminum is relatively inexpensive and can offer high reflectance (more than 90%) and good coverage of the solar spectrum. Among aluminum, stainless steel, and silver, aluminum displays the highest reflectance at the lower limit of the spectrum of solar UV radiation received at Earth's surface (˜290 nm). At this wavelength, stainless steel has 55% reflectance and silver has less than 10% reflectance.
However, the performance of aluminum metal deteriorates due to oxidation. Surface treatments such as anodizing and polyvinyl fluoride coating increase the useful life of reflective aluminum. Total reflectance includes specular and diffuse reflectance. Specular reflectance consists of radiation reflected at an angle which mirrors the incident light angle while diffuse reflectance consists of radiation reflected at other angles. At roughly 290 nm, unprotected aluminum loses around 15% of reflectance in 7 years, and in 14 years it loses around 60%. Protection of aluminum using anodization method slows down this reflectance loss. This protection caused around a 10% reduction in reflectance at low wavelength (near 300 nm) but shows an improvement in time of deterioration. A PVF protection showed a 20% less reflectance loss after 4 years compared with non PVF-protected Aluminum.
All-Polymeric UV Reflecting Film
In the 1970's and early 80's, several US companies developed an interest in research related to solar application materials. One of the promising reflecting materials that was patented by DOW Chemical was an All-Polymeric material. This is a plastic material that is inexpensive, light in weight, can resist harsh environmental stresses and can be designed for a specific wavelength reflectance to suit different purposes. This film is made of alternating thin layers of polyvinyl fluoride and polymethylmethacrylate. These materials have different refractive index (n) that promotes internal reflection. This material is a promising reflection material for solar UV application since it shows a good reflectance (around 90%) for radiation wavelengths of 300-400 nm for 1300 polymer layers.
Transmitting Materials
Potential materials for use in solar UV applications for transmittance are silica based materials such as fused silica and quartz due to good transmittance (>90%) of UVA and UVB wavelengths. Other materials such as transparent polystyrene and Polyethylene terephthalate (PET) used in SODIS (solar disinfection) bottles (0.45-0.55 mm thick wall) also transmit wavelengths in near-UV (Mani et al., 2006). Polystyrene has 20 to 40% transmittance between 290 and 310 nm, around 70% between 310 and 350 nm and 85% above. PET has roughly 80% transmittance above 320 nm but poor transmittance below 320 nm (McGuigan et al., 1998, Heaselgrave et al., 2006). Also, fluoroethylenepropylene (FEP) resins are used to make plastic tubes that offer variable UV transmittance (around 50% for 0.79 mm thick wall).
UV Dose-Response Relationship Studies
Dose-response relationships allow determination of sensitivity of microorganisms (inactivation rate) to UV. This relationship between dose and microbial response is generally obtained from bench-scale experiments in which well-defined UV doses are delivered to a microbial population. In most cases, the device used to deliver UV radiation to the microbial target is a shallow, well-mixed reactor under a collimated beam.
The UV dose-response behavior of microorganisms follows different kinetic models; there are microorganisms (for example bacteriophages) for which UV dose-response behavior is effectively described by single event (first order) kinetics, at least for a limited range of UV doses and inactivation responses. Others follow the Series-Event model, whereby a microorganism has to pass through a series of photochemical events before starting inactivation (Severin et al., 1983). The latter behavior presents a shoulder at the dose response curve. Pennell et al. (2008) developed the Phenotypic Persistence model in which the tailing behavior observed for some microorganisms was accounted for. This persistence was attributed to microbial phenotypic variation, or shielding of microorganisms by particles or microbial aggregates (Pennell et al., 2008).
Hijnen and Medema (2005) and Hijness et al. (2006) presented reviews of dose-response behavior for several relevant pathogenic microorganisms from numerous studies generated using low pressure lamps (254 nm). Data from dose-response relationships for two pathogenic viruses, adenovirus and poliovirus, were fitted using linear regression and the resulting kinetic coefficients of these two viruses were tabulated together with other common pathogenic viruses in drinking water. Of the viruses, a double stranded DNA adenovirus was reported to be relatively UV resistant as compared to other viruses; it has the smallest inactivation rate constant (k) of 0.024 cm2/mJ. Also in these reviews, dose-response curves for two common pathogenic bacteria, Campylobacter jejuni and E. coli O157 were fitted using linear regression; kinetic coefficients for these two bacteria and other common bacteria in drinking water are presented in FIG. 6. Among bacteria presented in FIG. 6, Legionella pneumophila is the most UV resistant (k=0.444 cm2/mJ) and Vibrio cholera is the least UV resistant (k=1.341 cm2/mJ). Presented information indicates that C. parvum (k=0.243 cm2/mJ) is slightly more UV resistant than Giardia (k=0.282 cm2/mJ). An important point is that the Hijnen and Medema (2005) and Hijness et al. (2006) reviews used linear fits for all microorganisms and accounted for the shoulder effect using an intercept on the response axis.
Solar UV Dose-Response Relationship Studies
Solar radiation, which is a polychromatic source with spatial and temporal variations, poses a challenge quantifying its effect on microorganisms with respect to these variations. Also, researchers have tried to simulate solar radiation using solar simulators but it is difficult to get a representation of solar radiation distribution around the globe or the region of interest. Others have used actual solar radiation to conduct experiments, and hence their results are specific for the area where the experiment took place. The following text will review findings from some studies that used ambient solar radiation and solar simulators to generate solar UV dose-response behavior for common pathogenic organisms found in drinking water.
Viruses and Bacteriophages
Heaselgrave et al. (2006) used a solar simulator to expose Poliovirus to a global solar irradiance of 850 W·m−2 (UVA and visible wavelengths from 320 to 700 nm) and found that a 4.3 log10 and 2.2 log10 inactivation was achievable at 1.2*106 mJ/cm2 and 6*105 mJ/cm2, respectively. For the conditions of their experiments, these doses required 4 and 2 hours of exposure, respectively.
Bacteria
SODIS has been proven to be effective for inactivation of bacteria. Berney et al. (2006) generated solar UV dose-response relationships for four types of bacteria, E. coli K-12 MG1655, Salmonella typhi, Shigella flexneri, and Vibrio cholerae. The exposure was performed using summer sunlight in Switzerland at UV wavelengths ranging from 350-400 nm, 37° C., for 6-7 hours exposure; these conditions correspond to a total UV dose of approximately 2400 kJ/m2 (2.4*105 mJ/cm2). The dose-response curve for E. coli shows the curve with a shoulder; E. coli demonstrated essentially no inactivation until a threshold dose of approximately 1200 kJ/m2 (1.2*106 mJ/cm2) was exceeded and 6.5 log10 inactivation was achieved after receiving a dose of 2.4*105 mJ/cm2. Shigella flexneri (lower left) required delivery of a threshold dose of approximately 400 kJ/m2 (4*104 mJ/cm2) before inactivation was observed, 6.5 log10 inactivation was achieved at a solar UV dose of 2400 kJ/m2. The dose response for Salmonella typhi fit with a linear regression. Relative to E. coli, S. thyphi were resistant to solar UV exposure; only 1.5 log10 inactivation was achieved at a dose of 2.4*106 mJ/cm2. Vibrio cholerae solar UV dose-response behavior was fit with linear regression and demonstrated 6.5 log10 inactivation at 900 kJ/m2 (9*104 mJ/cm2).
Since the radiation had a cutoff at 350 nm it does not accurately represent regions where solar UV radiation may be received at wavelengths down to 290 nm. For example, in an experiment conducted under Kenyan solar conditions (intensity of 106 mW·m−2), 5-6 log10 units reduction of Salmonella typhi was reached at a dose of 229 mJ/cm2 (6 hours exposure) and total non-infectivity at 8 hours (a dose of 305 mJ/cm2) (Smith et al., 2000, Berney et al., 2006).
Temperature is known to affect non thermo-tolerant microorganisms. Salmonella typhi, E. coli and Shigella flexneri were inactivated faster for temperatures above 50° C. and Vibrio cholerae is rapidly inactivated for temperatures above 40° C.
Protozoa
Two species of protozoa, Cryptosporidium parvum and Giardia lamblia, are of concern in drinking water. They have caused many fatal disease outbreaks and are resistant to chlorine. Due to Cryptosporidium's robust oocyst structure and the ability of Giardia to form cysts, both of these protozoan parasites can survive in water for a long time. McGuigan et al. (2006) exposed samples containing Cryptosporidium parvum oocysts and a surrogate of Giardia lamblia (Giardia muris) cysts to UV radiation from a solar simulator with a lower wavelength limit of 320 nm and an irradiance of 870 W·m−2 (UVA portion was estimated as 45 W/m2) at an ambient temperature of 40° C. Infectivity essays (performed using neonatal mice) of C. parvum showed non-infectivity after 10 hours of exposure, corresponding to a dose of 3*106 mJ/cm2 (1.6*106 mJ/cm2 UVA). Giardia muris cysts were rendered completely non-infective to mice after 4 hours exposure, corresponding to a dose 1.3*106 mJ/cm2 (6.5*10−4 mJ/cm2 UVA). The authors indicated that Giardia muris used in this study were believed to have higher UV resistance than G. lamblia, thus the solar UV dose-response of G. muris was assumed to represent a conservative estimate of the UV dose-response behavior of G. lamblia found commonly in water (McGuigan et al., 2006).

Continuous-flow solar ultraviolet disinfection system for drinking water


The method and compositions of this invention provide an effective and reliable substitute for the currently employed ICA assay for diabetes. By providing a method for detecting autoantibodies to GAD.sub.65, IA-2 and a previously unidentified antigen termed IA-2.beta. herein, the method provides a chemical assay which has improved reliability. In addition, these antigens may be employed in therapeutic regimens aimed at achieving amelioration of the clinical condition.

Diabetes is a term that refers to a collection of diseases resulting in disordered energy metabolism and varying degrees of blood glucose elevations or hyperglycemia. One of the best characterized forms of the disease is that resulting in immunologically mediated destruction of the insulin secreting pancreatic beta cells. This severe form of the disease is termed Insulin-dependent Diabetes (IDD) since it is associated with progressive insulin deficiency and coincident symptoms such as weight loss, glycosuria and polyuria, and increased thirst or polydipsia. Other terms for this form of diabetes are Type 1 Diabetes (cf. Type 2 Diabetes which results from an inherent resistance to insulin action); Ketosis Prone Diabetes because there is abnormal generation of ketone bodies as a result of excessive breakdown of body fats due to the severe insulin deficiency; or Juvenile Diabetes, since virtually all diabetes that appears in childhood and adolescence is of this type (see Atkinson and Maclaren [1994] N. Engl. J. Med. 331:1428-1436).
Diabetes is a major public health problem, especially in Western countries. The incidence rates vary greatly worldwide, from as high as 40 per 100,000 persons in Finland to as low as 1-2 per 100,000 among Japanese, with the US in between. The peak incidence is during the pubertal years associated with increasing bodily demands for insulin associated with muscle growth. The prevalence rates in the US population under age 20 years is 0.25% and it approaches 0.4% over a lifetime, albeit an estimated 10-20% of patients with Non Insulin-dependent Diabetes (NIDD) or Type 2 or Maturity Onset Diabetes also have, in reality, slowly progressive IDD. Thus, it is estimated that there should be at least 1 million Americans affected by IDD.
Diabetes results in progressive damage to the blood vessels of the body, to a degree that depends upon the severity of hyperglycemia and its duration. The incident mortality rate for IDD has been calculated to be 7-fold higher than for age matched non diabetic controls. Whereas the decade long Diabetes Control and Complications Trial (DCCT) concluded in 1994 by the National Institutes of Health in the US showed that meticulous insulin replacement therapy would slow the appearance of damaged arteries, it was not able to prevent this since blood glucose levels were never kept within normal limits. Ocular complications of diabetes are the leading cause of new blindness in persons of 20-74 years of age. The risk of lower extremity amputation is 15-fold higher in those with diabetes, while more than half of the approximately 125,000 persons undergoing lower limb amputation do so as a direct consequence of diabetes. Approximately 40% of persons undergoing renal transplantations have kidney failure because of their diabetes, and the proportion due to diabetes continues to rise each year. Women with diabetes produce newborn infants with a 7% newborn mortality rate, albeit this outcome can be greatly improved with tight glycemic control during the gestation period. Other complications of diabetes include increased heart disease and stroke, loss of nerve cells or neurones innervating the limbs and intestine, impotence and infertility, cataract formation in the lens of the eyes, increased periodontal disease, and predisposition to infectious diseases especially from bacteria and yeast. Of all patients with diabetes, those with IDD have a disproportionate share of these complications because of its severity and usual early age of onset. In the US, the direct health care costs attributable to diabetes in 1994 have been estimated to exceed $120 billion. Thus it is important that the pathogenesis of IDD be understood and strategies be developed to prevent it as a fully expressed clinical disease.
Patients with IDD are unusually prone to other diseases that have become recognized to have autoimmune origins. These diseases include thyroiditis or Hashimoto disease, Graves disease, Addison disease, atrophic gastritis and pernicious anemia, celiac disease and vitiligo (Maclaren, N. K. [1985] Diabetes Care 8(suppl.):34-38). Evidence that IDD itself has an autoimmune nature began with histological studies of patients that succumbed at diagnosis which indicated that the islets were infiltrated with a chronic inflammatory (lymphocytic) infiltrate termed insulitis. This was supported in the early 1970s by reports of islet cell autoantibodies reactive to antigens within the cytoplasm (ICA) (Lendrum et al. [1975] Lancet 1:880-882) or confined to the islet cell surfaces (ICSA) (Maclaren et al. [1975] Lancet 1:977-1000) as detectable by indirect immunofluorescence. Later it was recognized that many patients also develop autoantibodies to insulin (IAA) before their diagnosis (Palmer et al. [1983] Science 222:1337-1339) as well as to insulin receptors (Maron et al. [1983] Nature 303:817-818). Autoantibodies were also reported to an islet cell protein composition of 64,000 M.Wt. in man (Baekkeskov et al. [1982] Nature 298:167-169), in the Biobreeding (BB) rat model (Baekkeskov et al.[1984] Science 224:1348-1350) and in the Non Obese Diabetic (NOD) mouse model (Atkinson and Maclaren [1988] Diabetes 37:1587-1590). 64 kDa antigen has subsequently been reported to be the lower molecular weight isoform of glutaric acid decarboxylase (GAD.sub.65) (Baekkeskov et al. [1990] Nature 347:151-156) (Kauffman et al. [1992] J. Clin. Invest. 283-292). GAD is an enzyme that converts glutamate into the membrane stabilizing neurotransmitter called gamma amino butyric acid or GABA. In addition to autoantibodies to GAD, peripheral blood mononuclear cells were shown to be autoreactive in patients developing IDD (Atkinson and Maclaren et al. [1992] Lancet 339:458-459; and Harrison et al. [1993] Lancet 341:1365-1369). Indeed a leading possible cause for IDD is that immunity to enteroviral proteins (developed through infection by Coxsackie or closely related viruses) that have structural homologies to GAD, may in the genetically predisposed individual, trigger an autoimmune response to islet cells because of this molecular mimicry (Atkinson and Maclaren [1990] Scientific American 262:61-71; Kauffnman et al. [1992] J. Clin. Invest. 89:283-292; Atkinson, Maclaren et al. [1994] J. Clin. Invest. 94:2125-2129).
Since immunological markers predate the clinical onset of IDD often by many years, their possible value in disease prediction became increasingly realized (Maclaren, N. K. [1988] Diabetes 37:1591-1594), permitting in turn options for therapeutically induced delays in diabetes onset to be considered (Muir and Maclaren [1993] J. Autoimmunity 16:301-310). Indeed by 1994, multicenter trials attempting to prevent IDD through prophylactic parenteral insulin or oral insulin therapies had been initiated in the US (the DPT-1 trial), as well as in Europe using prophylactic nicotinamide (the ENDIT trial). Among relatives, the appearance of IAA was shown to predate onset of IDD (Atkinson and Maclaren [1985] Diabetes 35:894-898) while ICA proved to be valuable to the prediction of IDD in relatives (Riley, Maclaren et al. [1990] N. Engl. J. Med. 323:1167-1172) as well as in the general population (Schatz, Maclaren et al. [1994] J. Clin. Invest. 93:2403-2407), as modifiable on the basis of coincident IAA (Krischer, Maclaren et al. [1993] J. Clin. Endo. Metab. 77:743-749). While not ideal, the predictability of IDD based upon the ICA test provided the basis for the DPT-1 and ENDIT trials mentioned above. Furthermore, autoantibodies to the 64 kDa islet cell protein also proved to have utility in IDD prediction (Atkinson, Maclaren et al. [1990] Lancet 335:1357-1360), as eventually realized by the chemical assay for autoantibodies to GAD.sub.65 (Schott, Maclaren et al. [1994] J. Autoimmunity 7:865-872). These studies made it important to resolve the nature of all of the islet cell autoantigens involved in the pathogenesis of IDD (Atkinson and Maclaren [1993] J. Clin. Invest. 92:1608-1616). Whereas ICA, as determined by indirect immunofluorescence of human cryocut pancreatic sections, was likely to represent multiple autoantigens (Genovese et al. [1992] Diabetologia 35:385-388), GAD soon proved to be one of these (Atkinson, Maclaren et al. [1993] J. Clin. Invest. 91:350-356). Insulin, however, was not a component of ICA unless the pancreatic sections were first chemically "fixed" before being used as tissue substrate.
Recently, a 3.6-kb cDNA with a 2,937-bp open reading frame was isolated from a human insulinoma subtraction library (ISL-153) as described by Lan et al. ([1994] DNA and Cell Biology 13:505-514, herein incorporated by reference). The predicted amino acid sequence and in-vitro-translated product of IA-2 cDNA revealed a 979-amino acid protein with a PI value of 7.09 and a molecular mass of 105,847 daltons. The protein sequence is consistent with a signal peptide, an extracellular domain, a transmembrane domain and an intracellular domain. The extracellular domain contains an unusual cysteine-rich region following the signal peptide. The intracellular cytoplasmic domain of IA-2 possesses highly conserved regions similar to the catalytic domains in members of the protein tyrosine phosphatase (PTP) family. Northern blot analyses showed that IA-2 mRNA was expressed in five of five freshly isolated human insulinomas, rat and mouse insulinoma cell lines, and in enriched normal mouse islets. It was also found in normal human brain, pituitary, pancreas, and brain tumor cell lines, but not in a variety of other normal or tumor tissues. Based on the sequence and expression data, it appears that IA-2 is a new member of the receptor-type PTP family that is expressed in islet and brain tissues. The involvement of the molecule in beta cell autoimmunity or IDD was queried but was not disclosed or suggested in that work.
More recently, Payton et al. ([1995] J. Clin. Invest. 96:1506-1511) reported on the relationship of 37 kDa and 40 kDa tryptic fragments of islet antigens in IDD to the IA-2 molecule reported by Lan et al., supra. Payton et al. concluded that the 40 kDa fragment is a tryptic product of the IA-2 molecule but that the 37 kDa molecule, while sharing some antigenic determinants with the 40 kDa molecule, was a fragment of an as yet unidentified molecule.
We report herein, for the first time, the amino acid sequence and nucleotide sequence of both the mouse and the human counterparts of a new IDD associated autoantigen, referred to herein as IA-2.beta.. This antigen, alone or in combination with other IDD associated antigens such as IA-2 and GAD.sub.65, is useful in the prediction (diagnosis), treatment (therapy), and prevention (prophylaxis) of diabetes.

Materials and methods for detection and treatment of insulin-dependent diabetes

The United States of America as represented by the Department of Health and Human Services


A method and a device for signal decision, a receiver and a channel condition estimating method for a coding communication system are disclosed. A plurality of add, compare and select (ACS) circuits each sequentially determines metrics at a particular trellis tracing rate assigned thereto. The metrics are sequentially added in order to select the most probable path. An M break-up circuit 30 compares the path metrics of the most probable paths and breaks up unlikely paths over a plurality of circuits. The path metrics of probable paths are sequentially written to respective metric memories and again fed to the ACS circuits for trellis tracings. This is repeated until the M break-up circuit 30 selects M paths out of paths fed from N (N>M) ACS circuits. The M paths are delivered to a decision circuit while survivor paths are written to respective path memories. The decision circuit selects one of the M path metrics having the smallest value, reads the path out of the path memory, traces it back, and then outputs decoded bits via an output terminal.

1. Field of the Invention
The present invention relates to a method and a device for signal decision, a receiver and a channel condition estimating method for a coding communication system. More Particularly, the present invention relates to a method and a device for signal decision, a receiver and a channel condition estimating method for a coding communication system which are feasible for mobile communication using, e.g., a digital handy phone or mobile phone.
2. Description of the Background Art
Recently, due to the spreading mobile communication environment, digital handy phones and mobile phones promoting the efficient use of limited frequencies have been standardized in various countries. In the USA, for example, a North American TDMA (Time Division Multiple Access) handy phone system (IS-54) and other TDMA handy phone systems have been standardized first, and then followed by a North American CDMA (Code Division Multiple Access) digital cellular system (IS-95) and other CDMA handy phone systems.
In the North American TDMA digital cellular system, a signal lying in the speech band is transformed to a code by a voice coding method called VSELP (Vector Sum Excited Linear Prediction). The code is converted to an error correcting code by, e.g., a convolutional code, CRC (Cyclic Redundancy Check) code, and interslot interleave. A synchronizing signal and control signals are added to the error correcting code in the format of a TDMA slot. Particularly, a speech signal and an FACCH (Fast Associated Control Channel) signal included in the control signals and used to switch cells are each encoded by a convolutional encoder having a particular code rate. For example, speech data and FACCH are encoded by a rate 1/2 and a rate 1/4 convolutional encoder, respectively. The resulting convolutional codes are selectively arranged in the data field of the same slot. The data constructed into a slot are transformed to preselected symbols by a modulating section using a .pi./4 shift DQPSK (Differentially Encoded Quadrature Phase Shift Keying) or similar scheme. The symbols are modulated by orthogonal modulation or similar modulation, superposed on a carrier of preselected frequency, and then transmitted.
On receiving a signal from a mobile station, a base station multiplexes it with slots received from other mobile stations at a full rate over up to three channels. Then, the base station transmits the multiplexed slots to the mobile stations as a frame signal.
Each mobile station removes the carrier from the received signal and demodulates the channel assigned thereto by, e.g., orthogonal detection, thereby detecting received baseband symbols. Noise contained in the received symbols due to fading and other causes is cancelled by, e.g., an equalizer. Then, the original slot signal is restored by differential logic decoding. The restored slots each including the speech data or the control signals are decomposed into independent signals. These signals are each output to either a control section or voice decoding section. As a result, the reproduction of the speech data, position control and other functions assigned to the mobile station are executed.
On the other hand, in the North American CDMA digital cellular system, a signal lying in the speech band is encoded to speech data by, e.g., variable rate speech encoding called QCELP (Qualcomm Codebook Excited Linear Prediction). This speech coding scheme changes the transmission rate in accordance with the ratio of the duration of a speech. For example, for a 20 millisecond frame format, speech data are encoded at code rates of sixteen bits (0.8 kilobits per second or kbps), forty bits (2.0 kbps), eighty bits (4.0 kbps) and 172 bits (8.6 kbps). CRC codes are added only to the speech data encoded at the rates of 8.6 kbps and 4.0 kbps, thereby producing a 9.2 kbps code and a 4.4 kbps code. Further, tail bits are added to all the encoded speech data in order to cause them to converge to the same condition when decoded. As a result, there are produced 9.6 kbps, 4.8 kbps, 2.4 kbps and 1.2 kbps codes. The signals with the tail bits are each constructed into a symbol by convolutional coding and then caused to recur in accordance with the respective code rate. Consequently, the symbols are provided with a uniform symbol rate, e.g., 19.2 kbps. Further, these signals are subjected to interleaving in order to form respective frames. The frames are each subjected to spread coding by false noise and then subjected to orthogonal transformation using, e.g., a Walsh function. The transformed signals are divided into two phases and subjected to spectrum spreading by OQPSK (Offset Quadrature Phase Shift Keying) modulation using a short PN code or similar pilot false random number sequence. The resulting signals are individually superposed on a carrier and then transmitted.
A base station having received a signal from a mobile station multiplexes it with signals received from other mobile stations in the same frequency band over up to fifty-five channels.
On receiving the OQPSK signal from the base station, the mobile station demodulates it to output a baseband signal. The demodulated baseband signal is reconstructed into the original signals by, e.g., a rake receiver circuit called a finger circuit and effecting synchronization to the pilot false random number sequence, frequency synchronization, and inverse spreading. The reconstructed symbols are deinterleaved and then decoded by Viterbi decoding. At this instant, the signals each having a particular rate are re-encoded and then compared with the original received signal for a decision purpose. The signal coincident with the original received signal is determined to have the rate of the signal. This signal is subjected to error correction and transformed to the original speech data by a voice decoder or vocoder.
The conventional systems described above have some issues yet to be solved, as follows. In the North American TDMA digital cellular system, information for distinguishing the speech data and the control signals or FACCH signal is not added. This requires the receiver side to determine whether a received signal is speech data or whether it contains FACCH. Also, in the North American CDMA digital cellular system using a variable rate vocoder, information for identifying the code rate is not sent to the receiver side. The receiver side therefore must identify the rate of a received signal.
In any case, the receiver side initially executes channel decoding (error correction) corresponding to the encoder of the channel with all the possible signals. Each decoder calculates the reliability of the respective result of decoding, i.e., estimates channel conditions. Among a plurality of decoders included in the receiver side, the decoders not matching the encoder used at the transmitter side cannot decode the signal correctly. Indexes representative of channel conditions and output from the channel condition estimator of each decoder are expected to have a distribution differing from the decoder matching the encoder to the decoder not matching it. The receiver estimates the signal encoded at the transmitter side by using the above difference.
Under these circumstances, signal decision executing the above identification is significant with the receiver. Incorrect signal decision has a critical influence on the performance of the entire communication system. For accurate signal decision, an implementation for estimating channel conditions which are the key to the decision is essential. For example, a CRC code or similar error correcting code or a known code sequence shared by the transmitter and receiver constitutes an overhead against information to be interchanged. For example, in the North American CDMA digital cellular system, as for the 8.6 kbps and 4.0 kbps codes, a twelve-bit and an eight-bit CRC error detecting code are added to an eighty-bit information source code. These two error detecting bits can be used to estimate channel conditions. However, the 2.0 kbps and 0.8 kbps codes are not provided with any error detecting code. Moreover, because channel condition estimation using any of the above schemes includes the specifications of an encoder, it cannot be added to a communication system whose specifications have already been established.
Technologies relating to the present invention are disclosed in the following documents:
(1) "TIA/EIA/IS-54B Cellular System Mobile Station--Base Station Compatibility Standard", section 18.104.22.168.1.1 Bit Error Rate (BER) Measurement Technique; PA1 (2) "TIA/EIA/IS-95 Mobile Station--Base Station Compatibility Standard for Dual Mode Wideband Spread Spectrum Cellular System", section 220.127.116.11.2 Forward Traffic Channel Structure; PA1 (3) Hideki Imai "Code Theory", the Institute of Electronics, Information and Communication Engineers of Japan, section 5.3 Error Detection by Cyclic Code; PA1 (4) "Q0256 K=7 Multi-code rate Viterbi decoder Technical data sheet", FIG. 9, "Re-encode and compare circuit"; and PA1 (5) "A Viterbi algorithm with soft-decision outputs and its applications", J. Hagenauer, P. Hoeher, GLOBECOM-89, pp. 1680-1686.

Method and device for signal decision, receiver and channel condition estimating method for a coding communication system


Disclosed herein is a process for producing a postbiotic extract, which includes providing a first material having a first isoelectric point ranging from pH 1 to pH 6 and a second material having a second isoelectric point ranging from pH 4 to pH 8, admixing the first material and a probiotic microorganism with water having a pH greater than the second isoelectric point, so as to form a mixture, adding the second material into the mixture and then adjusting a pH of the second material-added mixture to between the first and second isoelectric points so that a precipitate is formed, and subjecting the precipitate to a cell wall isolation treatment to obtain the postbiotic extract. Use of the postbiotic extract is also disclosed.

Probiotics are resident normal flora of the intestinal tract and believed to play important roles in regulating proper intestinal immunity and digestion by balancing intestinal microflora. These beneficial microorganisms are widely used as live microbial dietary supplement and can help restoring intestinal microfloral balance. Many species of lactic acid bacteria (LAB), such as Lactobacillus spp., Lactococcus spp., Streptococcus spp., Enterococcus spp., and Bifidobacterium spp., are generally considered as probiotics. Furthermore, some of Bacillus spp. and some yeasts and Saccharomyces spp. have also been found as suitable candidates.
Probiotics are viable by definition, and their stability and viability are considered to be crucial for their health benefits. Paraprobiotics or postbiotics have emerged to denote that non-viable microbial cells, microbial fractions, or cell lysates might also offer physiological benefits to the host by providing additional bioactivity. Postbiotic efficacy is based on the microbial metabolites, proteins, lipids, carbohydrates, vitamins, organic acids, cell wall components, or other complex molecules that are generated in the matrix that is fermented. These postbiotics have drawn attention because of their clear chemical structure, safety dose parameters, long shelf life and the content of various signaling molecules which may have anti-inflammatory, immunomodulatory, anti-obesogenic, antihypertensive, hypocholesterolemic, anti-proliferative, and antioxidant activities.
Postbiotics can be obtained using cell disruption methods, which include heat, enzymatic treatment, solvent extraction, and sonication. However, these methods usually have low extraction efficiency and use large amounts of solvents.
Thus, there is still a need to develop a new method for efficiently producing a postbiotic from a probiotic microorganism.

Postbiotic extract and preparation process and use thereof