The present invention relates to a clamp apparatus that clamps a workpiece or the like that is to be supplied for machining processing, and in particular relates to such a clamp apparatus in which it is arranged to perform clamp driving while multiplying the clamping force that acts on a piston member by fluid pressure.
In a clamp apparatus that employs fluid pressure, it is possible to strengthen the clamping force by increasing the pressure reception area of the piston member. However, in this case, the clamp apparatus is increased in size, and this is disadvantageous because it reduces the freedom in designing the system. Thus, various types of clamp apparatus have been implemented in which the clamping force is strengthened by the provision of a force multiplication mechanism (servomechanism). In particular, there are a number of examples of provision of a force multiplication mechanism when pressurized air is used as the pressurized fluid.
In the clamp apparatus described in FIG. 4 of JP Patent 5,129,378: a cylinder bore is formed within the clamp main body; a first piston fitted in the cylinder bore, and an axial second piston fitted into the first piston, are installed so as to slide freely; an output rod is formed integrally with the second piston; a tubular portion that projects from above into the interior of the upper end portion of the first piston is formed integrally with the clamp main body; and there is provided a force multiplication mechanism which multiplies force generated by fluid pressure acting on the first piston and transfers the result to the second piston. There is also provided a compression spring for maintaining clamping force to bias the first piston in the direction for clamping operation.
The force multiplication mechanism includes: a plurality of support holes in the tubular portion; a plurality of spheres installed in these support holes so as to be movable in radial directions; a part conical surface that is formed on the inner surface of the upper end portion of the first piston; and a plurality of cam grooves that are formed on the second piston so as to be capable of contacting against the plurality of spheres. A first fluid pressure operation chamber is defined below the first and second pistons in the cylinder bore, and a second fluid pressure operation chamber is defined above the first and second pistons.


This invention relates in general to reducing heat energy in semiconductor devices, and more particularly, to thermal conductors embedded within semiconductor chip structures for removing heat from one or more conductive circuit members thereof, wherein the conductive circuit members are disposed within or on a low k dielectric material having a low thermal conductivity. More specifically, the invention addresses the problem of removing heat generated by copper wiring within low dielectric glasses and nanofoams in semiconductor chip structures.
Modern Very Large Scale Integrated (VLSI) chips require cooling to improve reliability of their circuitry and interconnects, to increase their circuit switching performance, and to regulate thermally generated noise in their circuits. Cooling reduces the likelihood that a metal wire will form voids or a contact will become open. It also reduces the extent of time-dependent transistor mobility and threshold degradation which adversely affects circuit performance and operation. Furthermore, in typical complementary metal oxide semiconductor (CMOS) microprocessors, every reduction in temperature of 10xc2x0 C. produces a 2% rise in operating frequency. For CMOS transistors, high temperatures yield significantly larger leakage currents, due to the thermal generation of carriers. This deleterious current doubles every 11xc2x0 C. and is known to adversely affect the functional operation of dynamic and analog circuits.
As VLSI circuits shrink to improve performance and increase operating frequencies, higher amounts of heat are generated, for example, due to constant switching of these devices. The removal of heat within a semiconductor chip structure thus becomes a major obstacle to the efficient performance of the device. Therefore, a need continues to exist for enhanced heat removal techniques for semiconductor devices.
In addition to the continued reduction in chip size, new materials are being incorporated to increase circuit performance. For example, dielectric materials with a dielectric constant (k) lower than that of conventional oxide reduce the parasitic capacitance between neighboring conductors, thereby improving circuit speed. However, most low k dielectrics are also lower in density than silicon oxide, and exhibit lower thermal conductivities as well thus further increasing the need for enhanced heat removal techniques.
Forming conductive lines and vias for semiconductor connections can be accomplished by a variety of methods. Prior techniques have used deposition and subtractive etch of metal to form conductive lines, followed by deposition of a dielectric layer and etch of vias therein to connect conductive lines above and below the dielectric layer. Newer techniques include damascene and dual damascene processes. In these techniques, a dielectric is deposited and patterned with trenches for conductive lines (in a damascene process) and for lines and vias (in a dual damascene process). Metal is then deposited and any metal overlying the dielectric outside of the vias and the trenches is removed by a chemical mechanical polish (CMP).
The metal that has traditionally been employed in such processes is aluminum. However, today""s chips are designed to run very fast and two effects limiting speed are conductive line resistance and RC coupling induced delay due to higher wiring density and closer spacing of conductive wires. Copper, which has a lower resistance, is replacing aluminum for wiring of semiconductor chip structures. RC coupling is being addressed by the use of lower dielectric constant (low k) dielectrics, such as porous silicas or polyimide nanofoams to replace conventional silicon dioxide dielectrics. However, the combination of copper and low k porous material creates a problem with heat dissipation. Because of the improved resistance and lower RC coupling that a copper/low k dielectric combination affords, more power per unit time is applied to the line, significantly increasing the heat dissipation requirements. These porous low k materials characteristically do not provide heat dissipation as well as high density glass dielectrics. Therefore, as the temperature of copper lines continues to increase due to current flow, resistance also increases, degrading device performance. To add to the problem, certain low k dielectrics, especially organic foam dielectrics, will degrade both structurally and electrically at temperatures around 350xc2x0 C. This temperature has been observed to be exceeded in copper wires on some products. Thus, there is a need for techniques which may be integrated with copper/low k dielectric semiconductor interconnection structures to improve the heat dissipation capability thereof so that device performance may be maintained optimal and consistent.
To summarize, therefore, the present invention comprises in one aspect a semiconductor chip structure which includes a substrate having first and second opposing surfaces, and at least one electrically conductive circuit member disposed above the first surface of the substrate. The at least one electrically conductive circuit member resides at least partially on a dielectric material, with the dielectric material being disposed between the at least one electrically conductive member and the substrate. The dielectric material has a low dielectric constant and a first thermal conductivity. The semiconductor chip structure further includes at least one thermal conductor thermally coupled to the at least one electrically conductive circuit member to provide a path for heat escape from the electrically conductive circuit member during operation. The at least one thermal conductor has a second thermal conductivity, and the second thermal conductivity is greater than the first thermal conductivity. A thermal sink is also provided thermally coupled to the second surface of the substrate, wherein the at least one thermal conductor facilitates heat transfer from the at least one electrically conductive circuit member to the thermal sink.
In a further aspect, a method of fabricating a semiconductor chip structure is provided. The method includes: providing a substrate having first and second opposing surfaces; forming at least one electrically conductive circuit member above the substrate on a dielectric layer, wherein the dielectric layer resides between the at least one electrically conductive circuit member and the substrate and has a low dielectric constant and a first thermal conductivity; disposing at least one thermal conductor thermally coupled to the at least one electrically conductive circuit member to provide a path for heat escape from the electrically conductive circuit member during operation, wherein the at least one thermal conductor has a second thermal conductivity, the second thermal conductivity being greater than the first thermal conductivity; and forming a thermal sink thermally coupled to the second surface of the substrate, wherein the at least one thermal conductor facilitates heat transfer from the at least one electrically conductive circuit member to the thermal sink.
To restate, semiconductor chip structures are described herein having one or more integrated thermal conductors for dissipating heat generated by conductive circuit members, for example wiring levels, disposed above the substrates of the chip structures. Each thermal conductor can comprise a thermally conductive plug or a stack of plugs which facilitate thermal coupling of heat produced by one or more conductive levels to the substrate of the chip structure and/or an upper surface of the structure. In one embodiment, the thermal conductors are placed in strategic locations within the semiconductor chip structures and either directly physically contact the circuit members to be cooled or pass close thereto so as to be thermally coupled to the members. As one example, the conductive circuit members reside on or within a first dielectric material having a first thermal conductivity and the stack of plugs comprise a second dielectric material having a second thermal conductivity, wherein the second thermal conductivity is at least 3xc3x97 greater than the first thermal conductivity. More particularly, the present invention solves the problem of cooling semiconductor chip wiring when dielectrics having low thermal conductivity are used for interlevel isolation. The invention can be employed within a structure using copper wiring in combination with low k dielectric glasses and nanofoams.
As an enhancement, a thermal sink is thermally coupled to a second surface of the substrate opposite the first surface above which the conductive circuit members are disposed. The at least one thermal conductor is positioned to facilitate heat transfer from the at least one electrically conductive circuit member to the thermal sink disposed over the second surface of the substrate. Preferably, one or more thermally conductive via structures are formed in the substrate integral with the thermal sink for further facilitating thermal transfer from the at least one thermal conductor into the thermal sink.
Additional features and advantages are realized through the techniques of the present invention. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention.


This invention relates generally to steam turbines, and more particularly to improved apparatus for controlling a flow of steam to such turbines.
In a steam turbine generator system, the turbine is normally maintained at a constant speed and steam flow is varied to adjust the torque required to meet the electrical load imposed on the generator. This type of control is provided by a main control system which varies the flow of steam to the high-pressure turbine, and in some instances to the low-pressure turbine, to meet the load demand. The main control system is designed to accommodate for normal changes in load demand and to smoothly adjust the turbine operating conditions to the new demand. However, if the electrical load is suddenly lost or reduced significantly, a commensurate reduction must be made in the flow of steam through the turbine or the turbine will overspeed, possibly causing turbine damage. The main control system does not possess sufficiently rapid response characteristics to accommodate for such sharp variations in load demand, especially in high power to inertia ratio turbine systems.
As is well known, large steam turbines generally include multiple nozzle chambers through which steam is directed into turbine through turbine blades which are rotated thereby. Nozzle chamber activation (i.e., steam admission thereinto) is regulated by valves which open to provide steam flow from steam supply conduits into the nozzle chambers, and close to obstruct steam flow thereinto. Inactive valves are completely closed at valve points in an ideal valve position, while active valves are wide open. In reality, to improve load response, the last valve that has opened is not in the wide open position before the next valve begins to open. A valve point is defined as a state of steam admission in which each active valve is in the completely open, non-obstructing configuration or each inactive valve is in the completely closed, full obstructing configuration. It can be shown that maximum turbine efficiency can be obtained from the use of an infinite number of valve points which, in turn, requires an infinite number of valves.
Of course, a finite number of valves must be used on steam turbines with that number of valves being dictated by compromises between improved turbine performance and increasing capital cost for increasing numbers of valves. One or more valves control the flow of steam into each nozzle chamber. Nozzle chamber activation refers to the process of increasing steam flow into the nozzle chambers from the time steam flow thereinto (i.e., completely activated) is achieved. Deactivation refers to the process of decreasing steam flow into the nozzle chambers. When multiple valves are used to regulate steam flow into a single nozzle chamber, those valves typically modulate together. Since such valves modulate together, turbine efficiency is actually a maximum when the nozzle chambers are each in the completely activated or completely deactivated state. Heretofore, the nozzle chambers were activated in a predetermined sequence such that once the nozzle chamber was activated during increasing load on the turbine, it was not deactivated until the load on the turbine decreased. One of the few restraints on nozzle chamber activation sequence was that single shock operation was preferred over double or multiple shock operation. That is, it is usually a preferable practice to activate nozzle chambers such that a newly activated nozzle chamber (i.e., after minimum admission) is circumferentially adjacent at least one previously activated nozzle chamber. One illustrative method for admitting steam into a steam turbine is disclosed in U.S. Pat. No. 4,325,670, issued Apr. 20, 1982 to George J. Silvestri, Jr., assigned to the assignee of the present invention, and incorporated herein by reference.
One recurring problem encountered by such turbines, however, is known in the art as low cycle thermal fatigue. With many older turbines being relegated to cycling operations such as load following and on-off or "two-shifting" operation, the potential for low cycle thermal fatigue is increased significantly. The problem of low cycle thermal fatigue can nevertheless be minimized in newer turbines by placing individual actuators for each valve in the steam chests of the turbines. Older steam chests, such as those used in the mechanical hydraulic (MH), analog electric hydraulic (AEH), and digital electric hydraulic (DEH) turbine control systems, may not have individual valve actuators, nor may they have sufficient space between the valves to accommodate individual valve actuators. This is especially true in those cases where the actuator incorporates springs necessary to insure rapid closure of the valves during turbine trips.
A solution to such problems would be the wholesale but costly replacement of the steam chests. However, such wholesale replacement would not only be costly, but would also be extremely time consuming, thereby leading to an inordinate amount of turbine down time. Another solution would be to modify the steam chests of such turbines as described in the above referenced U.S. Ser. No. 107,735, filed Oct. 13, 1987. That is, turbine operations may be improved in a conventional steam turbine by improved steam chest means. The steam turbine, as is typical, has a casing including inlet means for receiving a flow of steam by the steam chest means. Comprising a plurality of valves each of which are set for a minimum admission of the flow of steam to the inlet means below 100%, bar lift means for actuating at least one pair of the valves, high pressure means for actuating remaining ones of the plurality of valves, and means for controlling the bar lift means and high pressure means, the steam chest means thereby allows the turbine to be transferred between a full-arc (or maximum) admission mode and a partial-arc (lower level) admission mode.
In steam chests of the internal bar lift type, the bar is shortened or removed such that only the two innermost valves of a four-valve steam chest are still actuated by the bar lift means, while the two outboard valves at each end of the steam chest are replaced with ones having individual high pressure actuators. For those steam chests of the end bar or external bar lift type, the pivot on the fixed end of the bar is replaced with another servomotor such that the actuator rod of the new servomotor incorporates the pivot for the external bar. By a combination of lifts of the existing servomotor and the new servomotor, it is possible to operate at full-arc admission at start up and to make the transition from full (or maximum) to partial-arc (and vice versa) at whatever level of load is desired and whatever value of partial-arc admission is consistent with first stage requirements and optimum loading conditions.
It is well known that low load and part load operation of steam turbines with sliding throttle pressure not only reduces the above mentioned low cycle thermal fatigue, but also improves the heat rate. In particular, operation in a hybrid mode (i.e., a combined mode of operation with constant pressure-sequential valve and sliding throttle) results in a maximum heat rate benefit while reducing the change in first stage exit temperature, thereby reducing low cycle thermal fatigue. With hybrid operation, a partial-arc admission turbine is operated in the upper load range by activating individual valves to effect load changes along with constant throttle pressure operation. As load is reduced, when a particular valve point is reached, valve position is held constant and throttle pressure is varied or slid to achieve further load reductions. On units with essentially 100% admission at maximum load, hybrid operation with a 50% minimum first stage admission achieves the heat rate benefit of constant throttle pressure operation. Additionally, when valve loop losses are considered, hybrid operation has superior thermal performance to partial-arc designs operating with constant throttle pressure and having admission points below 50% at loads below from 65 to 70& of maximum value. For units with considerably less that 100% admission at maximum load, optimum hybrid operation is achieved at the valve point where half of the valves are wide open and half are closed. It is for this reason that the above referenced U.S. Ser. No. 107,735 provides one method and apparatus for a valving sequence on turbines having steam chests without individual valve actuators in such a manner that the valves which correspond to 50% first stage admission (or half of the total number of valves) all open simultaneously.
However, start up procedures that increase rotor life require a different operating mode than hybrid mode operation. Full-arc admission during turbine roll, for example, has proven beneficial for rotor warmup and more uniform heating as well as reducing the steam-to-metal temperature mismatches that increase low cycle thermal fatigue. It has also been noted that maintaining full-arc admission operation beyond synchronization of the turbine up to some level of load can be beneficial. Full-arc admission operation at part load, however, cannot be achieved on turbines having steam chests without individual actuators for which the valves are set for minimum first stage admissions below 100%. It has also been noted that an expected increase in rotor life is achievable when the transfer from full to partial-arc is made during the loading cycle as compared to full-arc admission operation all the way to full load.
It is, therefore, apparent that a steam chest having the capability of valve transfer from full to partial-arc admission and vice versa would be extremely desirable for turbines utilized in cycling operations. As mentioned herein above, U.S. Ser. No. 107,735, to which the present application is a continuation-in-part, discloses various embodiments of one method and apparatus for achieving such results. The present application, on the other hand, discloses an alternative method and apparatus for achieving the same.


The present invention relates to an electronic flash control device for a TTL light control type camera, and more particularly to an electronic flash control device which is free from the difficulty that light emission by the electronic flash is stopped by a noise component occurring before a suitable quantity of output light is obtained.
When it is necessary to photograph an object having a low luminance or to correct the amount of exposure, an electronic flash is generally used to increase the luminance of the object. The electronic flash is either built into the camera or is provided separately and can be connected to the camera. Whether the electronic flash is built into the camera or provided separately from the camera, it is essential to control the light emitting conditions of the electronic flash so that the amount of light applied to the object by the electronic flash has a predetermined value. In order to meet this requirement, the camera is provided with an electronic flash control device.
The electronic flash control device will be described with reference to a TTL light control type camera employing an electronic flash. FIG. 4 shows an example of a camera of this type. More specifically, FIG. 4 is a block diagram outlining the arrangement of a camera having an automatic focusing (AF) function and a built-in electronic flash proposed by the present applicant.
First, the arrangement of the camera shown in FIG. 4 will briefly be described. In FIG. 4, reference numeral 31 designates a camera body, and 11 represents a photographic lens mounted on the camera body 31.
The photographic lens 11 includes a lens system 15 including a focusing lens 13 which is movable along the optical axis and contributes to the focusing operation, and a drive force transmitting mechanism 17 for transmitting a drive force from a drive source provided for the camera body 31 to the movable lens 13. The photographic lens 11 further includes a lens ROM (read-only memory) 19 storing aperture value data of the photographic lens, position data of the movable lens 13, and data as to whether or not operating the electronic flash built into the camera body is suitable for the photographic lens, and a group of electrical contacts 21 which are connected to electrical contacts 57 on the camera body 31.
On the other hand, the camera body 31 includes an optical system having a main mirror 33, an auxiliary mirror 35, a focusing screen 37, and a pentagonal prism 39, an image pickup section 41 used for an automatic focusing operation, a drive mechanism 43 for driving the movable lens 13 in the photographic lens 11, a light detecting element 45 used for automatic exposure (AE) control for the purpose of TTL light control, a light detecting element 47 operated when the electronic flash is used, a central display section 49 for displaying camera conditions, a display unit 51 provided in the view-finder for indicating an AF or AE mode, the built-in electronic flash 53, a sequence motor 55 for winding or rewinding the film, a group of electrical contacts 57 provided on the side of the camera body which are connected to the group of electrical contacts 21 on the side of the photographic lens, a release switch 59, and a synchronizing contact 61 such as an X contact.
The camera body 31 further includes a microcomputer, namely, an IPU (indication processing unit) 71 for controlling the central display section 49, a PCU (power control unit) 73 having an E.sup.2 PROM 73a for interfacing with the image pickup section 41 and controlling the sequence motor 55 and an AF motor 43, the lens stop and the shutter release magnet, another microcomputer, namely, a DPU (data processing unit) 75 for performing photometric arithmetic operations and controlling the display unit 51 in the viewfinder, etc., and a central control microcomputer, namely, a CPU (central processing unit) 77. The CPU 77 controls the IPU 71, the PCU 73, the DPU 75, and the lens ROM 19 in the photographic lens 11.
The above-described built-in electronic flash 53 is provided above the pentagonal prism 39 and substantially at the middle of the camera body 31 so that the light flash can be readily applied to an object. When the electronic flash 53 is not in use, its light flash emitting section is retracted into the camera body. When it is in use, the light flash emitting section is protruded therefrom by operating a push button (not shown). The camera is designed so that an auxiliary electronic flash can be additionally connected thereto.
Next, an electronic flash control device for the above-described camera will be described. FIG. 5 is a diagram showing the above-described electronic light flash 53 and the electronic flash control device in detail. In FIG. 5, reference numeral 81 designates the electronic flash control device. The device 81 includes as essential components the CPU 77, the DPU 75, the PCU 73, the light detecting element 47, the release switch 59 and the X contact 61. The electronic flash 53 includes a booster circuit 53a, a main capacitor 53b, a light emitting circuit 53d having a light emitting tube 53c, and a light emission stopping circuit 53e. The electronic flash 53 is connected to the electronic flash control circuit 81 through a trigger signal terminal 53f and a quench signal terminal 53g. When necessary, the aforementioned auxiliary electronic flash is connected to the electronic flash control circuit 81 through auxiliary electronic flash connecting contacts corresponding to the above-described contacts 53f and 53g which are provided at predetermined positions on the camera body 31.
The operation of the electronic flash control device 81 thus constructed will be described with reference to the timing diagrams shown in FIGS. 6(A) through 6(J).
The release switch 59 is turned on after the camera has selected the electronic flash operation mode. Then, the CPU 77, after carrying out a series of processing operations, starts detecting the variation of the voltage at the X contact. In response to the variation of the voltage at the X contact (SWX in FIG. 6(A)) which occurs when the shutter is fully opened, the CPU 77 supplies a trigger signal X.sub.TRIG shown in FIG. 6(B) to light emitting circuit 53d in the electronic flash 53 via trigger signal terminal 53f. In response to the trigger signal, the light emitting circuit 53d supplies an electrical signal S.sub.X shown in FIG. 6(C) to the light emitting tube 53c. As a result, the light emitting tube 53c emits light. (See FIG. 6(G)).
On the other hand, an integrator circuit 75a in the DPU 75 integrates the output signal of the light detecting element 47 in response to an integration start signal S.sub.S shown in FIG. 6(D) which the CPU 77 outputs in response to the trigger signal. The integration voltage S.sub.I of the integrating circuit, as shown in FIG. 6(E), gradually increases with time, and abruptly increases with the emission of light from the light emitting tube. The integration voltage S.sub.I is applied to one input terminal of a comparator 75b.
The CPU 77 applies a digital signal S.sub.D to a D/A (digital to analog) converter 75c prior to every photographing operation. The digital signal represents a suitable exposure value determined in accordance with the ISO data of the film loaded in the camera or exposure correction data when available. The digital signal S.sub.D is subjected to digital-to-analog conversion by the D/A converter 75c, the output of which is applied to the other input terminal of the comparator 75b. The output terminal of the comparator 75b is connected to one input terminal of an AND circuit in a quench signal output regulating circuit 75d in the DPU 75.
When, in the circuit thus constructed, the integration voltage S.sub.I reaches a reference value S.sub.O, the comparator 5b applies a signal to the AND circuit in the quench signal output regulating circuit 7.5d so that the quench signal is generated (in a manner to be described in more detail later). When, with an enable signal S.sub.E applied to the other input terminal of the AND circuit by the CPU 7, the integration voltage S.sub.I reaches the reference value, the regulating circuit 75d applies a quench signal Q.sub.U shown in FIG. 6(F) to the light emission stopping circuit 53e. In response to the quench signal, the emission of light of the electronic flash 53 is quickly suppressed as shown in FIG. 6(G).
The present applicant has conducted extensive research on the electronic flash control circuit described above and recognized that the output timing of the enable signal S.sub.E is very important. That is, depending on the enable signal, the control circuit may operate erroneously.
When the CPU 77 supplies the enable signal S.sub.E as shown in FIG. 6(H) to the quench signal output regulating circuit 75d before a noise pulse N.sub.T occurs within the electrical signal S.sub.X in response to the trigger signal as shown in FIG. 6(C), the circuit is operated erroneously and a false quench signal Q.sub.UF is produced as shown in FIG. 6(I), so that no light is emitted (See FIG. 6(J).) In practice, such noise pulses are often produced by the light emitting tube, and accordingly, in order to perform the emission of light correctly, it is essential to use a light emitting tube having excellent characteristics. As a result, during manufacture, it is necessary to perform an additional operation of selecting light emitting tubes suitable for the electronic flash control device.
In view of the foregoing, an object of the present invention is to provide an electronic flash control device which is free from the difficulty of the emission of the light flash being stopped by a noise component before a suitable amount of light is obtained.


U.S. Pat. No. 4,562,082 describes the .alpha.-factor precursor gene of Saccharomyces cerevisiae and purports to show DNA constructs of the S. cerevisiae leader sequence and heterologous genes that are useful for the secretory expression of the heterologous genes. EPA 83306507.1 describes the actual use of the S. cerevisiae .alpha.-factor leader sequence to obtain secretory expression of human epidermal growth factor in yeast. Copending U.S. patent application Ser. No. 522,909, filed Aug. 12, 1983, which is, in part, commonly owned with the present application, describes the use of "spacer-less" S. cerevisiae .alpha.-factor leader sequences to obtain more efficient secretory expression of heterologous genes.
Science (1985) 229:1219-1224 reports the use of S. cerevisiae .alpha.-factor sequences to direct the secretion of prochymosin. It was reported that most of the prochymosin produced was present in an intracellular insoluble form rather than being secreted. Although the invertase leader was more effective at directing secretion of activatable prochymosin, an extensive mutant screen was necessary to yield reasonable amounts of prochymosin secretion.
There has been no previous demonstration of the production of mating pheromones (.alpha.-factor and .alpha.-factor) by Kluyveromyces lactis cells or other Kluyveromyces species. This failure to identify such peptides in K. lactis may, in part, be due to the fact that mating in K. lactis is inducible; whereas in S. cerevisiae the mating pheromones are produced constitutively.
Notwithstanding the availability of the mentioned leader sequences for directing secretion of heterologous polypeptides in yeast, there continues to be a need for alternative sequences that may afford more efficient or more practical production of particular polypeptides. Accordingly, applicants sought to determine whether a K. lactis .alpha.-factor exists and, if so, whether it might be useful for directing secretion of heterologous polypeptides, such as prochymosin, in yeast.


An ultrasonic diagnosis device sends an ultrasonic signal to an inspection target, and visualizes an internal status of the inspection target based on reflected wave information thereof. This device is used for nondestructive inspection in a medical treatment region or an industrial region.
As to the ultrasonic diagnosis device, first, by processing a signal received via a probe, two data (identical phase component data (I data) and orthogonal phase component data (Q data)) are calculated. Then, based on I data and Q data (Hereinafter, they are called “IQ data”), internal data (A-mode data, B-mode data, color Doppler data (including a direction, an averaged flow velocity, a power, a distribution), M-mode data) are calculated. By applying a coloring or a scan transform to the internal data, the inspection target is visualized as image data. Moreover, in a diagnosis using this device, the power Doppler method for visualizing power data is also used. Hereinafter, for convenience' sake, the color Doppler data and the power Doppler data are called “color Doppler data”.
Regularly, the ultrasonic diagnosis device prepares a plurality of methods for visualizing IQ data and internal data as image data. A user can select any from the plurality of methods. Furthermore, some ultrasonic diagnosis device prepares a function to preserve the image data visualized. As a result, after the diagnosis in real time, the user can confirm the image data visualized in off-line. In order to switch the plurality of methods in off-line, by preserving not the image data already visualized but the reflected wave information (IQ data, or internal data) not visualized yet, the visualization processing needs to be applied to the preserved data again.
However, a data quantity of the reflected wave information is much larger than that of the image data visualized. Accordingly, preservation of all reflected wave information unprocessed is not realistic. Furthermore, if compression processing is applied to all reflected wave information inputted, processing quantity is enormous. As a result, processing time thereof becomes very long.


Conventionally, trucks in a conveyor are driven by a driving chain. In such a conveyor, the driving chain is moving at all times even while the trucks are stored in storage lines, which promotes occurrence of wear of the driving chain as well as noises. Moreover, in order to start the trucks, it is necessary to engage the driving chain with the pressure plate provided to the trucks, which causes a shock at the time of engagement. Such a shock of course becomes greater in proportion to the speed of the driving chain. For these reasons, the upper limit of the speed of the conventional conveyor has been some 18 meters per second. Thus, the conventional chain drive conveyors are not suitable for high speed conveyance.
One solution of this problem is to use a conveyor driven by linear motor. In known linear motor drive systems, primary members of linear induction motor are provided on the floor and reaction plates which constitute the secondary members of a linear induction motor are provided to the trucks, respectively; and by maintaining the gap between the two members accurately and energizing the primary members, the trucks are electromagnetically propelled.
However, if there is a horizontal curve in the conveying path, the locus of the reaction plate is likely to be diverted from the primary members; and if there are curves or undulations in the vertical direction, the reaction plates are subjected to movements up and down. Thus, there occurs unevenness of the gap, which will result in instability or reduction in the propelling force. Consequently, conventional linear motor drive systems have been used only in straight conveying lines.
Accordingly, one object of this invention is to provide a linear motor driven trolley conveyor which is capable of stably driving trucks even where there are horizontal curves or slopes in the conveying path.


1. Field of the Invention
The present invention relates to microprocessor architecture in general and in particular to a microprocessor architecture capable of supporting multiple heterogeneous microprocessors.
2. Description of the Related Art
A computer system comprising a microprocessor architecture capable of supporting multiple processors typically comprises a memory, a memory system bus comprising data, address and control signal buses, an input/output I/O bus comprising data, address and control signal buses, a plurality of I/O devices and a plurality of microprocessors. The I/O devices may comprise, for example, a direct memory access (DMA) controller-processor, an ethernet chip, and various other I/O devices. The microprocessors may comprise, for example, a plurality of general purpose processors as well as special purpose processors. The processors are coupled to the memory by means of the memory system bus and to the I/O devices by means of the I/O bus.
To enable the processors to access the MAU and the I/O devices without conflict, it is necessary to provide a mechanism which assigns a priority to the processors and I/o devices. The priority scheme used may be a fixed priority scheme or a dynamic priority scheme which allows for changing priorities on the fly as system conditions change, or a combination of both schemes. It is also important to provide in such a mechanism a means for providing ready access to the memory and the I/O devices by all processors in a manner which provides for minimum memory and I/O device latency while at the same time providing for cache coherency. For example, repeated use of the system bus to access semaphores which are denied can significantly reduce system bus bandwidth. Separate processors cannot be allowed to read and write the same data unless precautions are taken to avoid problems with cache coherency.


Drinking water has been, and continues to be, heavily treated for bacteria and other microscopic organisms that may cause infection in humans and other animals subsequent to consumption. In order to disinfect water supplies, halogenated materials have been introduced therein that have proven more than adequate for such a purpose. Unfortunately, although such halogenated compounds (chlorinated and chloraminated types, primarily) exhibit excellent disinfection capabilities, when present within aqueous environments at certain pH levels these halogenated compounds may generate byproducts that may themselves create health concerns. The United States Environmental Protection Agency (USEPA) in fact regulates four types of trihalomethanes (THM4) within drinking water. These THM4 are chloroform, bromoform, dibromochloromethane, and bromodichloromethane. Removal of such compounds from drinking water is not possible as for typical chlorinated and brominated disinfecting compounds, at least not at the same reliability level as for the disinfecting agents. Thus, residual amounts may remain within treated water supplies that may require further removal processing to be undertaken, or avoidance of ingestion if necessary. Of course, if the level of contamination is sufficiently low, initiation of such potentially expensive removal steps would be unwise from an economic perspective.
The USEPA currently has set a maximum contaminant level for these THM4 in drinking water of 0.080 mg/L. It is thus important to reliably analyze and measure the total amount of such contaminants in order to determine if removal if necessary.
The USEPA has instituted its own testing methods for such a purpose. For THM4, the primary test method is 502.2. The USEPA 502.2 method measures for individual and total THM4 as well as other volatile byproducts. This method utilizes a TRACOR® 540 gas chromatography with Hall/PID detectors, a Tracor LSC-2 sample concentrator, and a TEKMAR® 2050 Autosampler. Such a system is, again, very effective at measuring drinking water samples at the source, but remote analyses are not readily available as the entire system is too cumbersome to move to locations along a drinking water line. As such, on-line analysis through these protocols is difficult, expensive, and labor intensive to implement.
Measurement at the source (i.e., within a water purification plant location) may be effective for system-wide average readings; however, in the large supplies of water at such locations, the chances of proper sampling to that effect may be suspect since the contaminants may be present in varied locations, rather than definitely mixed throughout the tested water supply itself. Additionally, testing may not uncover the actual level of residual THM4 disinfection byproducts prior to the water supply being disbursed to distant dispense sites (transfer pipes, homes, schools, businesses, etc.). In any event, there is a relatively new rule in place that requires utilities to provide evidence of compliance with trihalomethane levels at multiple locations, rather than a straightforward system-wide average. There is thus a drive to implement remote testing via real-time, on-line methods for water supply THM4 contaminant level measurements.
Such a desirable on-line procedure has been difficult to achieve, however, particularly as it pertains to the determination of not only the total amount of THM4 within water supplies, but also the amount of each species of the same THM4 groups present within the tested water source. High performance liquid chromatography, utilizing electrospray ionization-mass spectrometry or ultraviolet absorbance detector, has been attempted. The sensitivity and selectivity of the high performance liquid chromatography methods are easily sacrificed without the cumbersome preparations in place, therefore requiring operator intervention during analysis. Again, this issue leads to serious drawbacks when on-line implementation is attempted.
Another methodology that has proven effective to a degree is post-column reaction-ion chromatography. This has shown promise, but only in terms of quantifying bromate ion concentrations in drinking water samples at a single microgram per liter level. This dual selectivity form (separation by ion chromatography column as well as the selective reaction with the post-column reagent with the analyte) offers an advantageous test method over the others noted above, except for the presence of more common anions, specifically chloride, at much higher concentrations within the sampled drinking water supply (mg/L instead of microgram). Separation of the THM4 species from other halogenated compounds (such as haloacetic acids), however has been problematic and caused certain degrees of interference in measuring total levels of both types of compounds within drinking water samples. Despite this problematic limitation, it was determined that fluorescence detection provided a much-improved detection protocol in comparison with ultraviolet and mass spectrometry possibilities, particularly for haloacetic acid concentrations. Thus, although such a fluorescence method of detection, coupled with the post-column reaction (again with nicotinamide reactant) and ion chromatography, exhibited the best results in terms of an on-line test method for haloacetic acid drinking water contaminant measurement levels, there remained a definite need for improvements in individual and total trihalomethane measurements and identifications within such test samples. To date, however, there has not been an analytical test protocol that has permitted implementation of such a system within an on-line real-time monitoring procedure with an acceptable degree of reliability. An automated system that provides such versatility and reliability has simply not been forthcoming within the pertinent art.


The present invention relates to a method for measuring the amount of gas that leaks through sealed packages. More specifically, the invention relates to gas leakage through packages that have been sealed by a cover of porous material fabricated as a mat of polyethylene fibers. This material acts as a permeable membrane to gases, but an impermeable membrane to bacteria. The membrane comprises a layer having pores which provide a tortuous path to the passage of bacteria; the material is commonly sold under the trademark designation xe2x80x9cTYVEC.xe2x80x9d The packages which use this material are typically semi-rigid plastic cases which protect medical devices and appliances after manufacture and before actual use.
The invention relates to U.S. Pat. No. 5,939,619, issued Aug. 17, 1999, entitled xe2x80x9cMethod and Apparatus for Detecting Leaks in Packaging,xe2x80x9d and U.S. Pat. No. 6,050,133, issued Apr. 18, 2000, entitled xe2x80x9cMethod and Apparatus for Detecting Leaks in Packaging.xe2x80x9d Both of these patents are owned by the assignee of the present invention. The present invention also relates to co-pending application entitled xe2x80x9cMethod for Measuring Gas Leakage From Sealed Packages,xe2x80x9d Ser. No. 09/676,621, filed Oct. 2, 2000, and owned by the assignee of the present invention. The present invention permits a measurement of leakage that is wholly non-destructive to the package.
Gas sterilization is widely used for medical devices that must be sterile at the time of use, but cannot be subjected to sterilization by the application of high temperatures. Examples of such medical devices include cardiac pacemakers and catheter-based monitoring devices such as blood pressure probes. Typically, the medical device is sealed within a package that is permeable to gases but impermeable to bacteria. The package is then placed in a gas sterilization chamber, and a sterilizing gas such as ethylene oxide is introduced into the gas-permeable package to achieve sterilization. The sterilizing gas is then removed from the package, leaving the interior of the package sterile and non-toxic.
In a typical design, the medical device is placed within a thermoformed rigid plastic tray equipped with a flat sealing flange. A sheet of gas-permeable membrane, such as DuPont TYVEK(copyright) 1073-B (medical grade) brand membrane, which is available from E. I. duPont de Nemours and Co., is then sealed to the sealing flange, typically by using an adhesive. The integrity of the seal is critically important to maintaining sterility. Leaks can result from incorrect setting of parameters in the automated sealing process, or from physical defects such as burrs on the face of the sealing equipment.
According to the known practice described in the prior art patents listed herein, a temporary barrier is formed over the gas-permeable layer, wherein the temporary barrier has an aperture with the gas-permeable layer to temporarily seal the gas-permeable layer except where the aperture is located. A tracer gas is applied under low pressure through the aperture so that it can enter into the interior chamber of the package. The entire package is placed into a larger sealed second chamber, and the concentration of tracer gas in the second chamber is measured, outside the package, to thereby measure the amount of tracer gas which has leaked through the package, presumably via leaks in the sealing flange, although leakage can also occur through pinhole defects in the plastic tray itself.
The methods described in the foregoing patents provide very accurate measurements and evaluations for sealed packages, under controlled conditions. However, in many applications, it is not necessary to achieve a high degree of accuracy in the leakage measurement, but is desirable to provide a quick evaluation of leakage as a production line test, to determine whether packages are leaking excessively. Excessive leakage is defined in terms of leakage beyond a predetermined range of acceptability, as a pass/fail parameter, and the precise degree of leakage does not need to by quantified. Methods for making this type of determination should produce results more quickly and at a lesser cost.
The present invention provides a pass/fail test which can be quickly performed at considerably less cost in terms of test equipment and testing time, because it relies on measurement of internal package gas pressure, and specifically pressure drop, caused by leakage of gas from within the package. The method of the present invention can be performed in a short time, perhaps 30-60 seconds, using very much less expensive equipment than prior art methods.
The present invention comprises a method for testing sealed packages of the type described herein for leakage, according to a more efficient and faster process than is known in the prior art. The method requires a barrier layer to be overlaid on the gas-permeable membrane of the package, the barrier layer having a single aperture to the gas-permeable membrane. A pressure-sensitive monitor is affixed over the aperture, to monitor the pressure inside the package, and more particularly, to monitor the relative drop in pressure caused by leakage from the package. The internal package gas pressure is initially incrementally increased as a step of the method, and the incremental drop in pressure is measured as a function of time, usually by determining whether pressure drops incrementally between two desired set points within a predetermined time increment.
It is a principal object and advantage of the present invention to provide a method for measuring leakage through packages under faster test conditions than have heretofore been known.
It is another object and advantage of the present invention to provide a leakage test method which does not destroy the package being tested.
Other and further objects and advantages of the invention will become apparent from the following specification and claims and with reference to the appended drawings.


1. Field of the Invention
The present invention relates to a MIS device, and particularly to an improvement of so-called LDD (Lightly Doped Drain) structure of a PMOS transistor and a NMOS transistor formed on the same substrate and a method of manufacturing the improved LDD structure.
2. Description of the Background Art
A device provided with multi-layered structure of metal-insulator-semiconductor is generally referred to as an MIS device. An MOS device is a kind of MIS device, in which an oxide film is used for an insulator of the MIS device.
Semiconductor devices in which a p-channel MOS field effect transistor (referred to as a pMOS transistor hereinafter) and a n-channel MOS field effect transistor (referred to as a NMOS transistor hereinafter) are formed on a single semiconductor substrate include a CMOS semiconductor device, for example. FIG. 6 is a sectional structure view of a conventional CMOS semiconductor device. A p well region 8a and a n well region 8b in contact with each other are formed on a surface of a silicon substrate 6. Thick field oxide films 7 are formed at given positions on the main surface of the silicon substrate 6. The p well region 8a surface surrounded by the field oxide film 7 forms a n MOS transistor forming region, and the n well region 8b surface surrounded by the field oxide film 7 forms a pMOS transistor forming region.
The nMOS transistor 20 has a gate electrode 1a on the surface of the p well region 8a with a thin gate insulating film 9 disposed therebetween. Sidewall spacers 3a and 3a composed of insulating films are formed on sidewalls of the gate electrode 1a. Also, a pair of source/drain regions including n.sup.- impurity regions 2a, 2a of relatively low concentration and n.sup.+ impurity regions 5a, 5a of relatively high concentration are formed in the p well region 8a surface. Such structure of source/drain regions is referred to as LDD structure. Source/drain interconnection layers 11, 11 are respectively connected to the surfaces of the n.sup.+ impurity regions 5a, 5a of the source/drain region.
Also, the pMOS transistor 30 includes a gate electrode 1b on the surface of the n well region 8b with a thin gate insulating film 9 disposed therebetween. Sidewall spacers 3b, 3b formed of insulating films are formed on the sidewalls of the gate electrode 1b. Furthermore, source/drain region composed of p.sup.- impurity regions 2b, 2b of relatively low concentration and p.sup.+ impurity regions 5b, 5b of relatively high concentration are formed at the surface of the n well region 8b. This source/drain region forms the so-called LDD structure. Moreover, source/drain interconnection layers 11, 11 are respectively connected to the p.sup.+ impurity regions 5b, 5b of the source/drain region. The silicon substrate 6 surface in which a transistor is formed is covered with a thick interlayer insulating layer 10.
Next, a method of manufacturing the above-described CMOS semiconductor device will be described referring to FIGS. 7A-7H.
First, referring to FIG. 7A, a p well region 8a and an n well region 8b are formed on a silicon substrate 6 surface, and thick field oxide films 7 are formed at given regions on the silicon substrate 6 surface. Furthermore, gate insulating films 9 are formed on the surfaces of the p well region 8a and the n well region 8b. A polysilicon layer 12 is deposited on the surface of the gate insulating film 9.
Next, referring to FIG. 7B, the polysilicon layer 12 is patterned into a rectangular form using the photolithography method and the anisotropic etching method to form the gate electrode 1a of the nMOS transistor and the gate electrode 1b of the pMOS transistor.
Moreover, referring to FIG. 7C, after covering the surface of the p well region 8a with a resist pattern 4a, p type impurity ions 15 such as boron (B) are implanted into the n well region 8b using the gate electrode 1b as a mask. By this ion implantation, p.sup.- impurity regions 2b, 2b of low concentration are formed on the n well region 8b surface.
Furthermore, as shown in FIG. 7D, after removing the resist pattern 4a on the p well region 8a surface, a resist pattern 4b is now formed covering the surface of the n well region 8b. Subsequently, n type impurity ions 16 such as phosphorus (P) or arsenic (As) are directed on the p well region 8a surface using the gate electrode 1a as a mask to form n.sup.- impurity regions 2a, 2a of low concentration.
Furthermore, as shown in FIG. 7E, after removing the resist pattern 4b, an oxide film 13 is deposited all over the surface of the silicon substrate 6 using the low pressure CVD (Chemical Vapor Deposition) method.
Subsequently, referring to FIG. 7F, the oxide film 13 is anisotropically etched to form sidewall spacers 3a, 3b having the same film thickness on the sidewalls of the gate electrodes 1a and 1b.
Next, referring to FIG. 7G, after forming a resist pattern 4c covering the surface of the n well region 8b again, n type impurity ions 17 such as arsenic are implanted using the gate electrode 1a and the sidewall spacers 3a as masks. Subsequently, after removing the resist pattern 4c, thermal treatment is applied for activating the implanted ions. Thus, n.sup.+ impurity regions 5a, 5a of high concentration are formed in the p well region 8a surface. The LDD structure of the source/drain region of a nMOS transistor is then completed.
Furthermore, referring to FIG. 7H, a new resist pattern 4d is formed covering the surface of the p well region 8a. P type impurity ions 18 are directed on the n well region 8b surface using the gate electrode 1b and the sidewall spacers 3b as masks. Next, after removing the resist pattern 4d, applying thermal treatment, the ions implanted into the n well region 8b are activated. In this way, the p.sup.+ impurity regions 5b, 5b are formed. Thus, the LDD structure of source/drain region of a pMOS transistor is completed in the above steps.
Subsequently, an interlayer insulating film 10 is formed on the surface of the silicon substrate 6, and a contact hole is formed at a given position. An interconnection layer 11 is then formed at a given position through the contact hole to finish the process of manufacturing a CMOS semiconductor device (not shown).
The progress of fine processing technique of element structure is pointed out as technical background of a CMOS semiconductor device with such LDD structure as described above. The tendency of element structure miniaturization is seen in the aspects such as shortening of the gate length according to the scale down rule and forming of shallow junction region in a MOS transistor. The "scale down rule" is described in VLSI Electronics Microstructure Science, Volume 18, "Advanced MOS Device Physics", Academic Press. Inc. 1989. Also, it means shortening of the gate length of a MOS transistor, that is, shortening of a channel, which causes various problems so-called short channel effect. That is to say, for example, hot carriers are generated due to the high electric field produced in the vicinity of a drain in a short channel MOS transistor, and a portion of the hot carriers are captured in a trap in the gate insulating film to form a new level. As a result, characteristic degradation such as shift of a threshold value voltage of a MOS transistor and a decrease of mutual transconductance are caused. The high electric field produced in the vicinity of a drain also caused degradation of the drain breakdown voltage due to the avalanche breakdown. The LDD structure of a MOS transistor is a device proposed to solve such problems. Especially, it restrains generation of the high electric field by forming an impurity region with moderately changing concentration distribution in the vicinity of the drain to obtain high avalanche breakdown voltage and a decrease of reliability degradation due to hot carriers.
In a miniaturization method of CMOS semiconductor devices, it is needed to reduce the gate length L.sub.Gp of pMOS transistor 30 and the gate length L.sub.Gn of nMOS transistor 20 and make the lengths equal. As the gate lengths L.sub.Gp, L.sub.Gn of pMOS transistor 30 and nMOS transistor 20 get longer, the gate capacitance increases to increase the RC constant, with the result that operation of transistors are delayed. Accordingly, the channel lengths Ln and Lp defined in a self aligning manner utilizing gate electrodes 1b and 1a are also preferably reduced to have the equal lengths.
However, turning to FIG. 6 again, the pMOS transistor 30 and the nMOS transistor 20 are provided with low concentration impurity regions 2a, 2b of the LDD structure having different shapes in a CMOS semiconductor device manufactured through the manufacturing steps described-above. That is to say, in the pMOS transistor 30, the diffusion length of the low concentration p.sup.- impurity region 2b is extremely small as compared to that of the nMOS transistor 20. Also, the channel length L.sub.p between the high concentration p.sup.+ impurity regions 5b, 5b are shorter than the channel length L.sub.n of the nMOS transistor 20. This is because, boron (B), impurity forming the source/drain region of the pMOS transistor 30, has a larger diffusion coefficient as compared to that of phosphorus and arsenic forming the source/drain region of the nMOS transistor 20. This is understood by comparing the steps shown in the above FIGS. 7G and 7H. In other words, in the nMOS transistor 20, the high concentration n.sup.+ impurity regions 5a, 5a formed in a self-align manner with respect to the sidewall spacers 3a slightly diffuse under the sidewall spacers 3a by the thermal treatment for activation. On the other hand, in the pMOS transistor, the high concentration p.sup.+ impurity regions 5b, 5b formed in a self-align manner with respect to the sidewall spacers 3b widely diffuse under the sidewall spacers 3b in the thermal treatment for activating. In this way, the diffused high concentration p.sup.+ impurity regions 5b, 5b cover the low concentration p.sup.- impurity regions 2b, 2b regions, so that the diffusion length of the low concentration p.sup.- impurity region 2b is decreased. Thus, punch through phenomena easily occurs between the pair of high concentration p.sup.+ impurity regions 5b, 5b narrowed due to diffusion of impurity of large diffusion coefficient. This punch through phenomena is further facilitated as the gate length becomes shorter while the device is refined.
As described above, the LDD structure of the pMOS transistor and the nMOS transistor composed of impurities of different diffusion coefficients are manufactured employing the sidewall spacers 3a, 3b having the same film thickness. Accordingly, if the film thickness of the sidewall spacers 3a, 3b is selected to be suitable for the LDD structure of the nMOS transistor, for example, resistance to the punch through between the high concentration p.sup.+ impurity regions 5b, 5b is easily degraded in a pMOS transistor. On the other hand, if the sidewall spacers are formed with film thickness suitable for the LDD structure of the pMOS transistor, the drain current between the source and the drain is degraded in the nMOS transistor 20. This is because, as the film thickness of the sidewall spacers 3a is increased, the diffusion length of the low concentration n.sup.- impurity regions 2a, 2a is increased, and the low concentration n.sup.- impurity diffusion layers 2a act as parasitic resistance between the source and the drain to degrade the drain current. In this way, in a conventional CMOS semiconductor device, the sidewall spacers 3a, 3b defining the low concentration impurity regions of the LDD structure are formed with the same film thickness in the pMOS transistor and the nMOS transistor, so that a LDD structure which can satisfy requirements of both of the pMOS transistor 30 and the nMOS transistor 20 could not be obtained. Conventionally, by the sacrifice of source-drain current degradation of the nMOS transistor 20 to some extent to prevent the punch through phenomena of the pMOS transistor 30, the film thickness of the sidewall spacers 3a, 3b has been determined focusing on the operational reliability.


Femtocell is a technology that allows users of wireless devices, such as cell phones, PDAs, laptops equipped with cellular communications capabilities, or the like, to install small base stations in the indoor environment using licensed spectrum in order to increase coverage and/or throughput. Femtocells may provide access between a wireless device and a mobile network operator (MNO) core network. For example, the femtocell may be coupled to the operator core network through the Internet. Femtocell base stations may be installed by customers of MNOs on the customer's premises. Aspects such as energy consumption and electromagnetic emission may therefore be important factors for customer acceptance of femtocell products. FIG. 1 illustrates a femtocell base station 110 operatively coupled to an operator core network 120 via an Internet connection 130. The femtocell 110 may operate as a base station for a wireless device 140. Alternatively, a macrocell 150 may operate as a base station for the wireless device 140.
Some technical standards related to Femtocell technology include 3GPP TS 25.367 V9.2.0, “Technical Specification Group Radio Access Network; Mobility Procedures for Home NodeB; Overall Description,” 3rd Generation Partnership Project, Stage 2 (Release 9), December, 2009; 3GPP TS 25.467 V9.1.0, “Technical Specification Group Radio Access Network; UTRAN architecture for 3G Home Node B (HNB),” 3rd Generation Partnership Project, Stage 2 (Release 9), December, 2009; and 3GPP TS 25.469 V9.0.0, “Technical Specification 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; UTRAN Iuh interface Home Node B Application Part (HNBAP) signalling,” 3rd Generation Partnership Project, (Release 9), December, 2009.
There are several differences between a femtocell base station and a traditional cellular base station. A femtocell base station typically connects to the core network using a broadband Internet connection such as DSL, cable or Optical Fibre. Additionally, a femtocell base station may be placed in a user's home or an office building, and typically does not belong to nor is it under direct control of a MNO. For example, an owner of a femtocell base station may want to restrict access to their femtocell since they pay the expense of maintenance and the broadband connection to their premises. As such, a closed subscriber group (CSG) is defined in 3GPP and other standard bodies (e.g., IEEE 802.16m) for a femtocell base station. In other words, a femtocell base station is typically accessible only to terminals which are members of this base station, except for emergency services.
The traditional practice of having radio equipment continually turned on can result in energy being wasted. In addition to wasting energy, always-on radio equipment can increase radio interference and radio emissions in nearby areas.
Some power-saving techniques have been proposed for non-femtocell base stations, such as macrocells. For example, Ericsson™ has introduced a Base Transceiver Station Power savings feature, wherein, during periods of low network traffic, those parts of the network that are not being used may be powered down. Alcatel-Lucent™ offers a feature called Dynamic Power Save which enables a GSM base station to monitor traffic activity on the network and switch off the amplifier when there is no information to transmit. However, these approaches are unsuitable for femtocell base stations, for example since they may require knowledge of the network traffic load and full ownership of the base stations by the MNO. Furthermore, such solutions may not fully leverage the potential capabilities of a femtocell, for example as enabled by the availability of closed subscriber groups.
Therefore there is a need for a solution that overcomes at least one of the deficiencies in the art.
This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.


Electronic devices, including portable electronic devices, have gained widespread use and may provide a variety of functions including, for example, telephonic, electronic messaging and other personal information manager (PIM) application functions. Portable electronic devices comprise several types of devices including mobile stations such as simple cellular telephones, smart telephones, Personal Digital Assistants (PDAs), tablet computers, and laptop computers, that may have wireless network communications or near-field communications connectivity such as Bluetooth® capabilities. In addition, electronic devices are also widely used in personal entertainment and infotainment systems, for example, portable media players and automobile infotainment systems.
The popularity of electronic devices is driven by user experiences and the interaction between people and the devices via user interfaces. User Interfaces (UIs) that are user friendly and intuitive, functional and stylish, vivid and life-like drive the attractiveness of the device to a consumer.
Improvements in the method of generating and presenting user interfaces are desirable.


Composite resins that are typical examples of dental compositions usually contain polymerizable monomer compositions including polymerizable monomers and additives such as a filler, a polymerization initiator, a polymerization inhibitor and a dye. In a composite resin including such components, a filler usually has the largest weight fraction followed by a polymerizable monomer composition and these two components represent a major proportion of the weight of the composite resin. The polymerizable monomer composition serves as a binder for the filler. The properties of the monomers, and the properties of cured products of the monomers are significantly influential on the properties and performance of the composite resin containing the monomer composition, and cured products thereof.
From the points of view of aspects such as the biological safety of monomers and the mechanical strength and wear resistance of cured products, the polymerizable monomer compositions frequently include radically polymerizable polyfunctional methacrylates. Typically, the polyfunctional methacrylate compositions are based on 2,2-bis[4-(3-methacryloyloxy-2-hydroxypropoxy)phenyl]propane (hereinafter, written as Bis-GMA) or 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl) dimethacrylate (hereinafter, written as UDMA), and contain triethylene glycol dimethacrylate (hereinafter, written as TEGDMA) to control the viscosity.
In the dental clinical practice, the use of composite resins in the restoration of tooth defects has a long history and is still expanding. However, the mechanical properties of cured composite resins are still insufficient. In particular, the poor strength obstructs the application of the resins to sites subjected to a high stress, for example, the use as molar tooth crowning materials.
In recent years, clinical experts strongly demand the expansion of the use of composite resins to such high-stress sites. Therefore, the development of composite resins having higher mechanical properties is an urgent necessity. As mentioned above, the properties of cured products of polymerizable monomer compositions used for composite resins significantly affect the properties of cured products of the composite resins containing the compositions.
Techniques have been reported in which Bis-GMA and UDMA that are widely used as main components of polymerizable monomer compositions are replaced by other monomers so as to enhance the mechanical strength of cured products of composite resins (Patent Literature 1 and Patent Literature 2).
Further, techniques aiming to improve main component monomers have been reported. For example, main component monomers are improved so as to enhance the refractive index of cured products of polymerizable monomer compositions (Patent Literature 3), and main component monomers are improved so as to enhance the degree of polymerization shrinkage between before and after the curing of polymerizable monomer compositions (Patent Literature 4).


1. Field of the Invention
The present invention relates to a tire tread monitoring system and more particularly pertains to a system for detecting the initial signs of tire tread separation while the vehicle is in motion.
2. Description of the Prior Art
The use of tire monitoring and warning devices are known in the prior art. By way of example, U.S. Pat. No. 3,489,998 to O'Neal discloses a pressure warning apparatus for a pneumatic tire. U.S. Pat. No. 3,665,388 to Johnsen illustrates a tire air pressure detection and signalling device. U.S. Pat. No. 3,934,223 to Barabino discloses a tire pressure warning system. U.S. Pat. No. 4,089,225 to Kraska discloses a system for residual tire life prediction. U.S. Pat. No. 4,570,152 to Melon discloses a magnetic tire monitor system. U.S. Pat. No. 4,717,905 to Morrison Jr. discloses a warning system for monitoring a condition such as air. U.S. Pat. No. 4,750,584 to Tanaka discloses a distance measuring device. U.S. Pat. No. 4,814,744 to Collins discloses a low pressure warning system. U.S. Pat. No. 5,436,612 to Aduddell discloses a audible vehicle monitoring apparatus. U.S. Pat. No. 5,793,285 to Wehinger discloses a method and device for monitoring a tire on a vehicle.
In this respect, the monitoring system of the present invention substantially departs from the conventional concepts and designs of the prior art, by providing a means specifically designed to detect the initial signs of tire tread separation while the vehicle is in motion.


The invention relates to an electrical appliance having a battery holder, which battery holder has a housing which can accommodate at least one battery and which battery holder can be inserted into a housing of the electrical appliance, locking means being provided for locking the battery holder in the appliance.
Such removable battery holders, also referred to as power packs, are used, for example, in electrically chargeable appliances such as drills. An example of this is described in DE-A1-39 02 442. The construction for locking such battery holders in the electrical appliance often comprises a large number of parts, which are usually made of a plastic.
It is an object of the invention to provide a removable battery holder for an electrical appliance, which holder has a comparatively small number of parts for locking the battery holder and which has a locking mechanism which is reliable, also in the long run.
To this end, the appliance in accordance with the invention is characterized in that the locking means are formed by two spaced-apart resilient plastic fingers which each have a projection and by at least one boss for cooperation with the projections of the resilient fingers which fingers and boss have been provided, respectively, on the housing of the battery holder and on the housing of the appliance or the other way around, and which resilient plastic fingers are supported, in the direction of their resilient action, by resilient limbs of a material having a stiffness greater than the stiffness of the resilient plastic fingers. The plastic fingers and the boss can simply be molded integrally with the housing of the battery holder and with the housing of the appliance, respectively. When the battery holder is fitted into the appliance the boss slides between the resilient fingers, upon which the projections are moved apart and subsequently come together after passage of the boss. The resilient limbs whose stiffness is greater than that of the fingers back up the resilient action of the plastic fingers, as a result of which a reliable operation and locking of the battery holder is achieved. To remove the battery holder from the appliance no release button as in DE-A1-39 02 442 is needed. Moving plastic parts are frequently subject to creep. Creep gives rise to a reduction of the force with which the battery holder is locked in the appliance. The resilient limbs prevent the locking mechanism from being adversely affected by creep. The resilient limbs form an additional part but they prolong the life of the mechanism significantly. Moreover, the resilient limbs have an additional advantage, as will be explained hereinafter.
Preferably, the material of the resilient limbs is an electrically conductive metal.
A preferred embodiment is characterized in that the housing on which the boss has been provided has electrically conductive limbs which upon insertion of the battery holder into the electrical appliance automatically make contact with the resilient metal limbs which serve for supporting the resilient plastic fingers. The metal limbs make electrical contact with the terminals of the battery (batteries). In their turn, the electrically conductive limbs are connected to a part to be energized of the electrical appliance.


1. Technical Field
This invention relates generally to flexible strapping mechanisms and, more particularly, to a flexible support device for removably securing an ice-pack to various joints and muscles of a human body.
2. Discussion
Ice-packs or hot-water containers are often used by athletes and non-athletes to reduce swelling and remove soreness from various joints or other areas of the human body, or such swelling or soreness as the result of muscular injury, or muscular inflammation or even arthritis. Securing an ice-pack or hot-water container to a traumatized joint for various periods of time often helps to alleviate the discomfort, swelling and/or soreness associated with such muscular injuries or other degenerative conditions.
When an ice-pack or hot-water container is intended to be applied to a particular joint or muscle for various periods of time, it becomes necessary to incorporate some means for securing the ice-pack or hot-water container securely against the inflamed or sore joint or muscle. Heretofore, this has commonly been accomplished by various types of tape, strapping and bandages which are adapted to be wrapped around the ice-pack or hot-water container and areas of the affected joint or muscle to thereby hold the ice-pack or hot-water container securely against the joint or muscle. Typically, such devices have proved to be time consuming and/or inconvenient to secure to the various joints of the human body. This becomes a particular drawback with athletes who incur minor injuries during sporting events. In such cases ice-packs are often periodically applied to the injured joint of an athlete during intermissions, half-times, etc., when an athlete is temporarily resting. When the athlete must periodically enter and exit a game or other event, the tape, bandage, etc., securing an ice-pack to an injured joint or muscle often has to be quickly removed or applied, while causing only a minimum of discomfort to the athlete.
Present devices for the above-described purpose often impede the quick and/or periodic application or removal of an ice-pack. Bandages are often wrapped around a limb or joint several times, with multiple bandages often being required to secure an ice-pack to various parts of the human body such as the shoulders. Such devices are therefore of limited value to athletes, in particular, where ice-packs, hot-water containers, etc., must be applied and removed periodically in a quick and efficient manner.
It is therefore a principal object of the present invention to provide a universal ice-pack holder operable to quickly and efficiently secure an ice-pack, hot-water container, etc., to a joint or muscle area of the human body.
It is a further object of the present invention to provide a universal ice-pack holder which may be used to secure an ice-pack, hot-water container, etc., to virtually any joint or muscle area of the human body in a quick and efficient manner.
It is still a further object of the present invention to provide a universal ice-pack holder which is comfortable to wear in contact with the skin for prolonged periods of time while reducing the risk of rashes or other forms of skin irritation.
It is yet another object of the present invention to provide a universal ice-pack holder for securing an ice-pack, hot-water container, etc., to a joint or muscle area of the human body, which is of a relatively simple and inexpensive construction.
It is still a further object of the present invention to provide a universal ice-pack holder which is manufactured of materials which stretch and generally conform to the shapes of various limbs of a human body, thereby enhancing the comfort of the ice-pack holder.


The present invention relates to polymer compositions having a specified pH to provide improved dispensing for wrinkle removal and/or reduction. The specified pH prevents staining of treated fabrics and methods for treating fabrics are provided in order to improve various properties of fabrics, in particular, reduction, removal, or prevention of unwanted wrinkles.
For preferred polymer compositions containing additional components it is particularly important to maintain the specified pH of the polymer compositions to maintain acceptable dispensing while also preventing precipitate formation during processing.
Wrinkles in textile fabrics are caused by the bending and creasing of the textile material which places an external portion of a filament in a yarn under tension while the internal portion of that filament in the yarn is placed under compression. Particularly with cotton fabrics, the hydrogen bonding that occurs between the cellulose molecules contributes to keeping wrinkles in place. The wrinkling of fabric, in particular clothing and certain household fabrics, is therefore subject to the inherent tensional elastic deformation and recovery properties of the fibers which constitute the yarn and fabrics.
In the modern world, with the increase of hustle and bustle and travel, there is a demand for a quick fix which will help to diminish the labor involved in home laundering and/or the cost and time involved in dry cleaning or commercial laundering. This has brought additional pressure to bear on textile technologists to produce a product that will sufficiently reduce wrinkles in fabrics, especially clothing and household fabrics, and to produce a good appearance through a simple, convenient application of a product.
U.S. Pat. No. 5,573,695, issued Nov. 12, 1996 to E. F. Targosz discloses an aqueous wrinkle removal composition containing a vegetable oil based cationic quaternary ammonium surfactant, and an anionic fluorosurfactant. Similarly, U.S. Pat. No. 4,661,268, issued Apr. 28, 1987 to Jacobson et al. discloses a wrinkle removal spray comprising an aqueous alcoholic composition containing a dialkyl quaternary ammonium salt and a silicone surfactant and/or a fluoro surfactant. U.S. Pat. No. 5,100,566, issued Mar. 31, 1992 to Agbomeirele et al., discloses a method of reducing wrinkles in fabric by spraying the fabric with an aqueous alcoholic solution of an anionic siliconate alkali metal salt. U.S. Pat. No. 4,806,254, issued Feb. 21, 1989 to J. A. Church discloses fabric wrinkle removal aqueous alcoholic solution containing glycerine and a nonionic surfactant. U.S. Pat. No. 5,532,023, issued Jul. 2, 1996 to Vogel, Wahl, Cappel and Ward discloses aqueous wrinkle control compositions containing silicone and film forming polymer.
In the present invention, wrinkle control in fabrics, including clothing, dry cleanables, linens, bed clothes, draperies, window curtains, shower curtains, table linens, and the like, is acheived without the need for ironing. The present invention can be used on wet, damp, or dry clothing to relax wrinkles and give clothes a ready to wear or use look that is demanded by today""s fast paced world. The present invention also essentially eliminates the need for touch up ironing usually associated with closet, drawer, and suitcase storage of garments.
An additional benefit of using polymer-based compositions in the present invention is that polymers provide improved benefits including any or all of the benefits named in the following list: garment shape, body, rewrinkle prevention, and/or crispness.
When ironing is desired however, preferred compositions of the present invention can also act as an excellent ironing aid. The present invention makes the task of ironing easier and faster by plasticizing fabric fibers and thus making it easier to work wrinkles out of the fabric. When used as an ironing aid, the compositions of the present invention help produce a crisp, smooth appearance, but also retaining a quality of softness.
The present invention relates to aqueous wrinkle reducing, removing and/or controlling compositions comprising polymer containing carboxylic acid moieties, that are preferably stable, well-dispersed opaque, translucent, or clear suspensions, dispersions, or solutions with the dispersed or solubilized polymer particulates being very small in particle size, that distribute evenly from dispensers to prevent staining. Specified pH solutions are acceptable if these have the low viscosity that is necessary to provide acceptable dispensing. The present invention also relates to preferred compositions containing, in addition to the essential carboxylic acid containing polymer and carrier, optional, but preferred ingredients, e.g. polyalkylene oxide polysiloxane, fabric care polysaccharides, odor control components, solvent, and minors such as perfume and preservative, adjusted to a specified pH to provide both good dispensing properties and improved stability to shear forces (e.g. stirring during processing or shaking that occurs during transit). The present invention further relates to methods of formulating such compositions, as well as fabric wrinkle control methods and articles of manufacture that comprise such fabric wrinkle controlling compositions. The fabric wrinkle control compositions typically comprise:
(A) an effective amount to control wrinkles in fabric of a polymer preferably selected from the group of polymers comprising carboxylic acid moieties that can be suspended, dispersed or solubilized at a specified pH range to produce a solution with a viscosity lower than the viscosity of that polymer composition at a pH above the specified pH range and with the viscosity of the solution preferably below about 20 centipoise (xe2x80x9ccPxe2x80x9d), more preferably below about 15 cP, even more preferably below about 12 cP, even more preferably below about 10 cP, still more preferably below about 7 cP and most preferably below about 3 cP, with the polymer incorporated at a level that is at least about 0.001%, preferably at least about 0.01%, and more preferably at least about 0.05%, and still more preferrably at least about 0.1% and even more preferably at least about 0.25% and most preferrably at least about 0.5% and at a level of no greater than about 25%, more preferably no greater than about 10%, even more preferably no greater than about 7%, and still more preferably no greater than about 5% by weight of the usage composition; mixtures of polymers are also acceptable in the present composition; and
(B) carrier, preferably water.
The preferred polymer compositions of the present invention can optionally further comprise:
(A) optionally, but preferably, silicone compounds and/or emulsions. Silicone compounds that impart lubricity and softness are highly preferred. Silicones that reduce surface tension are also highly preferred. A preferred class of silicone materials includes silicones modified with alkylene oxide moieties compounds;
mixtures of silicones that provide desired benefits are also acceptable in the present composition;
(B) optionally, an effective amount of a supplemental wrinkle control agent selected from the group consisting of (1) adjunct polymer (2) fabric care polysaccharides, (3) lithium salts, (4) fiber fabric lubricants, and (5) mixtures thereof;
(C) optionally, an effective amount of a supplemental surface tension control agent;
(D) optionally, an effective amount to soften fibers and/or polymer of hydrophilic plasticizer wrinkle control agent;
(E) optionally, but preferably, at least an effective amount to absorb or reduce malodor, of odor control agent;
(F) optionally, but preferably, an effective amount to provide olfactory effects of perfume;
(G) optionally, an effective amount of solubilized, water-soluble, antimicrobial preservative, preferably from about 0.0001% to about 0.5%, more preferably fromabout 0.0002% to about 0.2%, most preferably from about 0.0003% to about 0.1%, by weight of the composition;
(H) optionally, an effective amount to adjust and control pH of a pH adjustment system;
(I) optionally, other ingredients such as adjunct odor-controlling materials, chelating agents, viscosity control agents, additional antistatic agents if more static control is desired, insect and moth repelling agents, colorants, whiteness preservative; anti-clogging agents; and;
(J) mixtures of optional components (A) through (I).
The present compositions are preferably essentially free of materials that would soil or stain fabric under usage conditions, or preferably free of materials at a level that would soil or stain fabrics unacceptably under usage conditions.
The present invention also relates to concentrated compositions, including liquid, fluid and solid forms of concentrated compositions that may be diluted to form compositions with the usage concentrations for use under usage conditions. It is preferred that the concentrated compositions be delivered in forms that rapidly and smoothly dissolve or disperse to the usage concentration.
The present invention further relates to a method of making the present compositions.
The present invention also relates to articles of manufacture comprising the present compositions incorporated into a container, such as a spray dispenser, that can facilitate treatment of articles and/or surfaces with said compositions containing wrinkle control agent and other optional ingredients at a level that is effective, yet is not discernible when dried on the surfaces. The spray dispenser comprises manually activated and non-manual powered (operated) spray means and a container containing the wrinkle controlling composition.
The present invention also relates to the combining the composition with a substrate and/or device capable of containing said composition for release at a desirable time in a fabric treatment process to create an article of manufacture. Such articles of manufacture can facilitate treatment of fabric articles and/or surfaces with said pH adjusted polymer compositions containing wrinkle control agent and other optional ingredients at a level that is effective, yet not discernible when dried on the surfaces of said fabric. The article of manufacture can operate in mechanical devices designed to alter the physical properties of articles and/or surfaces such as, but not limited to, a clothes dryer or mechanical devices designed to spray fabric care compositions on fabrics or clothes.
The present article of manufacture can further comprise a set of instructions to communicate methods of using the present compositions to the consumer. When articles of manufacture comprise devices or substrates that dispense the said composition, preferred devices or substrates will disperse the said composition in a uniform manner so as to minimize staining.
The present invention also comprises the use of small particle diameter droplets of the present compositions to treat fabrics, in order to provide superior performance, e.g., the method of applying the compositions to fabrics, etc. as very small particles (droplets) preferably having weight average diameter particle sizes (diameters) of from about 5 xcexcm to about 250 xcexcm, more preferably from about 10 xcexcm to about 120 xcexcm, and even more preferably from about 20 xcexcm to about 100 xcexcm.


Corrosion is generally a problem in any system in which ferrous metals are in contact with aqueous solutions. Corrosion is the electrochemical reaction of metal with its environment. Corrosion is a destructive reaction which, simply stated, is the reversion of refined metals to their natural state. For example, iron ore is iron oxide. Iron oxide is refined into steel. When the steel corrodes, it forms iron oxide.
The metallurgy of boiler systems are predominantly iron-containing steel in contact with high temperature (approximately 200.degree. F., under 35-350 psig of pressure) aqueous solutions. Most industrial boiler and feedwater systems are constructed of carbon steel and sometimes with copper alloy and/or stainless steel feedwater heaters and condensers. Some have stainless steel super-heater elements.
Corrosion is one of the main causes of reduced reliability in boiler systems. The most common causes of corrosion are dissolved gases such as carbon dioxide and oxygen, under-deposit attack, low pH and attack of areas weakened by mechanical stress resulting in stress and fatigue cracking. Corrosion control in boilers varies with the type of corrosion encountered. Generally, corrosion in boilers may be controlled through procedures such as maintaining proper pH and alkalinity levels, reducing mechanical stresses, operating within design temperature and pressure specifications, by proper application of chemical corrosion inhibiting treatments and by controlling oxygen and boiler feedwater contamination. Generally boiler feedwater should be low in contaminants. The American Society of Mechanical Engineers (ASME) Consensus for Industrial Boilers specifies maximum levels of contaminants for corrosion and deposition control in boiler systems. The consensus is that feedwater oxygen, iron and copper content should be less than 7 parts per billion (ppb) oxygen, 20 ppb iron and 15 ppb copper for a 900 psig boiler and that pH should be maintained between 8.5 and 9.5 for boiler system corrosion protection.
It is commonly held that in boiler systems substantially free of oxygen (i.e., less than about 7 ppb oxygen) that ferrometal corrosion can be expressed in terms of the following equation: EQU Fe+2H.sub.2 O.fwdarw.Fe(OH).sub.2 +H.sub.2.
Therefore, Fe.sup.+2 (ferrous ion) is a useful material to determine the corrosion rate of ferrometals in substantially oxygen free systems such as boilers. However, in the presence of oxygen the following reaction occurs: EQU 3Fe(OH.sub.2).fwdarw.Fe.sub.3 O.sub.4 +H.sub.2 +2H.sub.2 O
Magnetite (Fe.sub.3 O.sub.4) is a complex of the hydroxides of iron (III) and iron (II) which can be expressed by the formula: EQU Fe.sup.3+ !.sup.IV Fe.sup.2+ Fe.sup.3+ !.sup.IV O.sub.4.
Other ferric-ferrous oxide species also exist, however, under the conditions present in most boiler water, magnetite is the most common species. As used herein the term "ferric-ferrous oxide" means magnetite as well as other ferric-ferrous oxide species such as maghemite (.gamma.Fe.sub.2 O.sub.3) and feroxyhyte (.delta.FeOOH) which are ferrimagnetic. Ferric-ferrous oxides are often introduced into a boiler system by boiler feedwater. Ferric-ferrous oxides can also be produced within the boiler through reaction of ferrous ions with trace free oxygen and via electrochemical reactions.
Ferrion chelation chemicals are compounds which form complex undissociated cations with divalent metal ions. Such chelation chemicals include 1,10-phenanthrolinre; 4,7-diphenyl-1,10-phenanthroline; 2,2.sub.1 bipyridine; 2,6-bis(2-pyridyl)-pyridine; 2,4,6-(bis(2-pyridyl)-1,3,5-triazine; phenyl 2-pyridyl ketoxime; 3-(2-pyridyl)-5,6-bis(4-phenylsulfonic acid)-1,2,4-nitrilotriacetic acid and salts thereof. Certain of these ferrion chelation chemicals react with ferrous ions to form colored species (ferroin reagents) which are useful in the coloromertric determination of ferrous ion concentration. It is generally believed that ferroin reagents do not change color when the reagent complexes with ferric (Fe.sup.+3) ions in water. However, some research suggests that oxides, such as magnetite, may be captured by the ferroin reagents and thus bias ferrous ion content determinations (see Matijevic, E. Han-Chyen, Chang, Interactions of Metal Hydrous Oxides with Chelating Agents: Part V Ferric-ferrous oxides-EDTA, J. Colloid Interface Sci., Fin. Chem. Lett. (1982); and Bohnsak, G. The Solubility of Ferric-ferrous oxides in Water and in Aqueous Solutions of Acid and Alkali (Essen: Vielkan-Verlag, 1987)).
Therefore, conventional techniques to measure ferrous ion content as an indicator of ferrous metal corrosion may inadvertently include some ferric-ferrous oxides concentration in the calculation of ferrous ion thereby yielding higher corrosion rate determinations then are actually occurring in the studied boiler system.
Thus a need exists for a method to remove ferric-ferrous oxides from a liquid containing ferric-ferrous oxides and ferrous ions.
A need also exists for a method to measure the ferrous ion concentration in boiler water without contamination of the rate determination results due to the presence of ferric-ferrous oxides in the boiler water.
It is, therefore, an object of this invention to provide a method for removing ferric-ferrous oxides from a liquid containing ferric-ferrous oxides and ferrous ions.
It is also an object of this invention to provide an accurate method to determine the corrosion rate of ferrous metals exposed to a boiler water in a boiler system which contains ferrous ions, ferric ions and/or ferric-ferrous oxides.