The present invention is applied, for example, to a liquid crystal display apparatus in which drive circuitry is formed integrally on an insulating substrate, wherein processing results from circuit blocks 41A, 41B on the side of a higher power supply voltage are inputted into the side of a lower power supply voltage through active elements performing on-off operation complementarily, and by the fall of the power supply voltage on this higher side, the output of these active elements is set to a predetermined level.

1. Technical Field
The present invention relates to a flat display apparatus and an integrated circuit and can be applied to, for example, liquid crystal display apparatus in which drive circuitry is integrally formed on an insulating substrate. In the present invention, processing results from a circuit block on the side of a higher power supply voltage is inputted to the side of a lower power supply voltage through active elements performing on-off operation complementarily, and the output of these active elements is set to a predetermined level by the fall of the power supply voltage on the higher side thereof, which can further reduce power consumption in the deep-standby mode or the like.
2. Background Art
In recent years, in a liquid crystal display apparatus that is a flat display apparatus applied to a mobile terminal device such as a mobile telephone, for example, there has been provided the one in which a drive circuit of a liquid crystal display panel such as a horizontal drive circuit and a vertical drive circuit is combined and integrated on a glass substrate which is an insulating substrate making up the liquid crystal display panel.
More specifically, in this type of liquid crystal display apparatus, a display unit is formed by arranging, in a matrix, pixels each composed of a liquid crystal cell, a polysilicon TFT (Thin Film Transistor) which is a switching element of this liquid crystal cell and a storage capacitor. In the liquid crystal display apparatus, the respective pixels of the display unit formed in this manner are sequentially selected on a line basis by the driving of gate lines by the vertical drive circuit. Furthermore, gradation data indicating the gradation of the respect pixels is sampled sequentially and circularly by the horizontal drive circuit to be collected on a line basis, and by driving respective signal lines according to a digital-analog conversion result of this gradation data, the respective selected pixels are driven by the gate lines according to the gradation data, thereby displaying a desired image.
In such liquid crystal display apparatus, power supplies required for the operation are generated from power supplied externally, in a DC-DC converter, which is a part of the drive circuit provided in the vicinity of the display unit and the resultant power supplies of a plurality of systems enable the operation. Specifically, the apparatus is arranged such that, for example, a power supply of 6V and a power supply of −3V are generated from a power supply of 3V that is supplied externally, and these power supplies of −3V, 3V, and 6V enable the operation.
Thus, in this type of liquid crystal display apparatus, for example, as shown in FIG. 1, a 6 V-system logic electronic circuit 1 which is a circuit block whose power supply voltage is 6V allows various types of processing to be executed at high speed and according to the results of the high speed processing, a 3 V-system logic electronic circuit 2 which is a circuit block whose power supply voltage is 3V is driven.
In a mobile telephone which is one of devices to which this liquid crystal display apparatus is applied, for example, as disclosed in Japanese Application Publication No. 10-210116, stopping the display of the liquid crystal display unit in a standby state prevents wasteful consumption of battery.
Specifically, in the mobile telephone, a backlight of the liquid crystal display apparatus is turned off by the control of a controller that controls overall operation, which reduces power consumption. Furthermore, the operation mode of the liquid crystal display apparatus is set to be a so-called deep standby mode.
Here, the deep standby mode is, in the liquid crystal display apparatus, an operation mode in which, although the power is supplied externally, by stopping the supply of various clocks as operation references, the operation of the drive circuit is stopped.
More specifically, when the operation of the liquid crystal display apparatus is stopped in this manner, the simplest method is a method of stopping the supply of power to the liquid crystal display apparatus. However, when such stop of the supply of power is executed outside of the liquid crystal display apparatus, the configuration becomes complicated for that purpose in the mobile telephone. In contrast, while a method of shutting off the power supplied externally inside of the liquid crystal display apparatus is considered, in this case, the configuration of the active elements relating to the control of the power supply is increased in size, which brings an increase in size to the shape of the liquid crystal display apparatus itself.
Therefore, in this type of liquid crystal display apparatus, the deep standby mode is provided, in which the supply of clocks is stopped to stop the operation and to reduce the power consumption. Furthermore, in this deep standby mode, the operation of the DC-DC converter is switched so that the lowest power supply voltage in the liquid crystal display apparatus is outputted, which prevents through-currents between circuit blocks having different power supply voltages.
More specifically, FIG. 2 is a block diagram showing a configuration of a part of a digital-analog conversion circuit in this type of liquid crystal display apparatus. In this type of liquid crystal display apparatus, a predetermined generation reference voltage is resistively divided by resistances in a reference voltage generating circuit to generate a plurality of reference voltages. The plurality of reference voltages are selectively outputted according to the gradation data to thereby apply digital-analog conversion processing to the gradation data, and according to this digital-analog processing result, the respective pixels are driven. Furthermore, for example, in the case where the pixels are driven by line inversion, the polarity of this generation reference voltage is switched on a horizontal scanning cycle.
FIG. 2 is a diagram showing a circuit block relating to the switching of the polarity of the generation reference voltage and the generation of the reference voltages in such manners. In the liquid crystal display apparatus, various reference signals in sync with the gradation data are processed by a circuit block whose power supply voltage is 6V to thereby generate a polarity switching signal of the generated reference voltage and this polarity switching signal and an inversion signal of the polarity switching signal are outputted to a reference voltage generating circuit 5 via buffer circuits 3, 4 operating by the power supply voltage of 6V.
The reference voltage generating circuit 5 is a circuit block operating by a power supply voltage of 3V and by driving switch circuits 6 and 7 each composed of a CMOS (Complementary Metal Oxide Semiconductor) by the output signals of the buffer circuits 3, 4, contact points of the switch circuits 6 and 7 are switched complementarily to switch the polarity of the generated reference voltage to be outputted to a resistance block 8. Thus, in the example as shown in FIG. 2, the generated reference voltage is switched between +3V and −3V.
In the reference voltage generating circuit 5, the resistance block 8 is composed of a series circuit of a plurality of resistances and reference voltages V1 to V30 is generated by resistively dividing the generated reference voltage by this resistance block 8.
In such a configuration, when the operation of the DC-DC converter is simply stopped, the power supply voltage falls to 0V in the circuit block of the power supply voltage 6V, and as a result, the output of the buffer circuits 3, 4 is held in a state of falling to 0V. In this case, in the switch circuits 6, 7 receiving the output of these buffer circuits 3, 4, switch circuits 6A, 6B, 7A, 7B making up the respective switch circuits 6, 7 are held in an on-state, which causes through-currents 16, 17 in the switch circuits 6, 7.
In this case, also, for the circuit block of the power supply voltage 3V, by making the power supply fall, through-currents can be prevented. However, the fall of the power supply of the circuit block of the power supply 3V ends up shutting off the power supplied to the liquid crystal display apparatus itself, which causes problem such as an increase in size of the liquid crystal display apparatus as described above. Therefore, in this case, the switching of the operation of the DC-DC converter allows the power supply of 6V to fall to 3V in the liquid crystal display apparatus to prevent the through-currents.
However, even when the power supply of 6V is made to fall to 3V by the switching of the operation of the DC-DC converter in this manner, leak current by the power supply voltage 3V eventually continues to flow in each active element. If such leak current can be reduced, the power consumption can be further reduced in the deep standby mode.

Flat display apparatus and integrated circuit


A skid steer loader having a main frame supported on four wheels, and a cab with upwardly extending side walls mounted on the main frame for providing an area in which an operator can control the loader. The loader is propelled by an engine operatively coupled to the wheels by a first assembly of suitable control components. A boom structure comprising a pair of arms and a mounting assembly is also mounted on the frame. A second assembly of suitable components is also coupled to the engine to provide appropriate control of the boom structure for raising and lowering the pair of arms. The first assembly of control components includes a pair of hydraulic motors for driving the wheels, and a system associated with the motors for selectively changing the speed ranges of the motors to change the speed at which the wheels propel the loader.

Over the years skid steer loaders have been known as agile, compact vehicles with a high degree of maneuverability and a wide range of applications in the agricultural, industrial and construction fields. These vehicles usually include an engine, a boom assembly and an operators compartment mounted on a frame supported by four wheels. Coupled to the engine are a main drive system and a lift system for the boom assembly. The vehicle is maneuvered by driving the wheels on one side at a different speed and/or in a different direction from those on the other side resulting in a turning motion, the severity of which is determined by the relative speeds.
Typically the engine, which is rear mounted for counterbalancing effect, drives a pair of hydrostatic pumps coupled to left and right mounted hydrostatic motors. Wheels on the left and right sides of the vehicle are driven by the left and right mounted motors through gears, chains and sprockets. In one known control arrangement, motion is controlled by an operator seated within the operators compartment by moving a pair of hand operated control levers which are linked to the pumps. The extent to which each lever is moved in a forward direction from a neutral position controls the amount of fluid supplied in a forward direction to its respective motor, and therefore the speed at which the wheels on that side of the vehicle will rotate. Similarly, the extent to which a lever is moved in the reverse direction from the neutral position will control the speed at which the associated wheels rotate in the reverse direction.
As mentioned above, skid steer loaders include a boom assembly. This assembly generally comprises a pair of lift arms and means for mounting the arms on the main frame. Attachments are usually operatively associated with the front of the lift arms. A separate hydraulic system is used to actuate the boom assembly via hydraulic lift cylinders which drive the lift arms. This system is also used to actuate one or two tilt cylinders which pivot the attachment with respect to the lift arms. In the control arrangement mentioned above, a pair of foot pedals conveniently located in the lower front area of the operator compartment control the flow of hydraulic fluid from a hydraulic pump to the lift and tilt cylinders.
In addition to material handling buckets, various other attachments such as snow blowers, trenchers, tree spades and augers which include their own hydraulic motors are commonly mounted to the boom assembly. An auxiliary hydraulic system is used to control the flow of hydraulic fluid between the hydraulic pump and the hydraulic motor of the front mounted attachment. It is common in prior art systems, using the arrangement mentioned above, for the flow of hydraulic fluid to the motor to be controlled by an auxiliary spool valve through actuation of a pivotally mounted handle on one of the control levers. The handle is normally biased to a neutral position. Pushing the handle (relative to the lever on which it is mounted) in one direction strokes the auxiliary valve in a first direction, thereby causing hydraulic fluid to flow to the front mounted attachment in a first direction. Pushing the handle in the opposite direction strokes the auxiliary valve so as to supply fluid in a reverse direction.
In an alternative prior art control arrangement, flow of hydraulic fluid to the lift and tilt cylinders is controlled by a pair of handles on the control levers. Movement of one handle relative to its respective lever controls the boom lift cylinders and movement of the other handle relative to its respective lever controls the bucket tilt cylinders. In this arrangement, if an auxiliary hydraulic system is used for controlling a hydraulic motor or cylinder for mounted attachments, then a foot pedal is utilized for operator actuation.
Further, with respect to prior art skid steer loaders, it has been found to be advantageous to employ a system that permits the vehicle to operate in high and low speed ranges. For example, when filling the bucket, maximum wheel torque is necessary for effective operation in most conditions. Therefore, a low range of speeds is most useful in this phase of the operation. But, when the dump site is situated a significant distance from the work site, as it often is, a higher range of speeds for transport is desirable, which thereby provides an obvious enhancement to the overall effectiveness of the vehicle. At the dump site the operator may wish to drop back to a lower range for maximum control when simultaneously raising the boom and dumping, such as when approaching and dumping into a truck. Finally, upon completion of such dumping task, the operator can shift back to the high range for travel back to the work site.
An assembly used in a system of the type described above, is illustrated on page 31 of Sperry New Holland Service Parts Catalog for Model L-781, L-784 and L-785 Skid Steer Loaders (1985), printed in U.S.A. and identified by catalog no. 5078132. In this arrangement an operating lever, located in the operator's cab, is coupled to a shaft assembly that moves the hydrostatic motor pintle shafts. When the lever is moved from a first position to a second position, the shaft assembly moves the pintle shafts from a high speed operating mode to a low speed operating mode.
Notwithstanding the successful operation of this prior art system, embodied in various models of skid steer loader vehicles manufactured and sold by the predecessor company of the assignee of the present application, applicants have embraced various needs and problems of that system. The below described invention is a new and useful solution that meets the needs of such prior art system, as well as other systems with similar demands, in a manner not heretofore known.

Speed range control system for a skid steer loader


Multi-well plates having contoured well designs allow multi-stage high throughput parallel assaying of ion channels or ion transporters. A well of a multi-well plate has a bottom region that is sized and shaped to simultaneously accommodate a sensing electrode and a pipette for delivering test compounds, wash fluid, and optionally ligands. The multi-well plates when coupled with an instrument having a pipette head and an electrode plate facilitates fluidic contact between cells and fluids delivered via a pipette for washing of wells with buffers or other wash solutions for serial exposure of test cells to various reagents or other stimuli. The control and test experiments are performed on the same cell (or cells) in a single well.

Ion channels are membrane proteins that are present in every cell of every living organism. The channels control flow of ions into and out of the cells and thus play a crucial role in cell functioning. Not surprisingly, ion channels constitute a very important class of drug targets. To efficiently develop new drugs, researchers need methods and devices that allow high-throughput screening of compounds (drug candidates) by their action on ion channels. Such drug screening methods and devices require mechanisms for measuring an ion channel's activity and mechanisms for applying compounds to the ion channels.
Ion channels are commonly studied with a technique called patch clamping. This technique involves measuring electrical signals (currents and/or voltages) from individual cells. The cells are arranged in an apparatus such that the magnitude of the electrical signal is directly related to the state of the ion channels, and in particular how much current they allow to pass. Thus, the technique allows direct electrical measurement of ion channel events in living cells, cell membranes and artificial membranes.
The whole-cell and perforated patch configurations of the patch-clamp are widely accepted as providing the best methods of measuring ion channel activity for drug screening. In these methods ion currents flowing through ion channels are measured directly and with high resolution by sensitive current amplifiers.
Unfortunately, current patch clamp instrumentation suffers from a variety of shortcomings, particularly with regard to high-throughput screening of ion channels, and particularly ligand-gated ion channels.

This patent is subject to a terminal disclaimer.

High throughput screening of ion channels


Breathable barrier fabrics for protective garments that form liquid impervious seams when overlapped and sealed together via heat-sealing, and the seams formed thereby. The breathable barrier fabric is a heat-sealable, liquid impervious fabric composed of a breathable, liquid impervious thermoplastic film layer having a first melting point and a nonwoven layer bonded to a first surface of the thermoplastic film layer. The nonwoven layer has a second melting point that is higher than the first melting point of the thermoplastic film layer. A second nonwoven layer having the second melting temperature may be bonded to a second surface of the thermoplastic film layer opposite the first surface such that the inner film layer has a lower melting point than the outer nonwoven layers. The heat-sealable, liquid impervious fabric has a moisture vapor transmission rate of at least 800 g/m2/day as determined by ASTM E96-00.

Protective garments that provide protection to a wearer of the protective garment from the outside environment and/or protection to the outside environment from the wearer of the protective garment are required to be breathable and at the same time to be liquid impervious to provide necessary barrier properties. For example, protective garments used in the medical field, such as gowns, drapes, masks and gloves, can protect the wearer from environmental elements such as blood, bodily fluids and other liquids as well as virus, bacteria and other microbes or micro-organisms carried in liquids. Protective garments used in the medical field and other fields, such as cleanroom apparel, may also provide protection from particulate matter, such as skin, or blood, bodily fluids and other liquids as well as virus, bacteria and other microbes or micro-organisms being released by the wearer into the environment.
As used herein, the term "protective garment" shall be construed broadly to mean all types of garments that provide one or more of the foregoing types of barrier protections and the term "liquid impervious" shall be construed broadly to mean being a barrier to liquids such as blood and other bodily fluids as well as to virus, bacteria and other microbes or micro-organisms carried in liquids. Breathability is the ability of a garment or fabric to allow water vapor to pass through it while preventing liquid from passing through it, and is expressed interchangeably as "moisture vapor transmission rate" (MVTR) or "water vapor transmission rate" (WVTR).
Multi-laminate, breathable, liquid impervious fabrics having desirous properties for use in protective garments and heat-sealing of such fabrics are known. For example, U.S. Pat. No. 7,390,376 to Palomo discloses multi-laminate medical fabrics, such as surgical gowns, having heat-sealed seams with fluid penetration resistance characteristics similar to the multi-laminate base material that do not require additional stitching or adhesive sealing techniques. Palomo's multi-laminate medical fabric structure has three layers—nonwoven fabric/impervious film/nonwoven fabric—where the outer nonwoven fabric layers have a melting temperature that is lower than the melting temperature of the inner impervious film layer. The heat-sealed seam seal is made to be impervious by melting the layers of the outer nonwoven fabric layers when overlapped, and preventing the inner impervious film layer from melting.
There exists a need in the art, however, for multi-laminate fabrics that form heat-sealed seams and methods for making protective garments having heat-sealed seams that utilize lower energy and permit faster sealing times while at the same time exhibiting the same breathability and liquid impervious properties of the multi-laminate fabrics.


A method for detecting the Bisection pattern for use in conjunction with the deinterlacing is to improve low angle direction detection capability. A method of Bisection pattern detection operates in an interlaced video containing both top and bottom fields. For each missing pixel in a current input field, a window W is constructed whose center pixel is at the considered missing pixel. A binary map is generated which includes rows of values corresponding to pixels in the window, wherein the values indicate if each element of the window is greater than the sample mean of the area surrounding the missing pixel. The number of value changes in the values in each row of the binary map is counted. It is then determined whether or not the missing pixel is within the Bisection pattern based on said counts. In order to maintain both the low angle edge direction detection capability and low misdetection probability, complicated areas are identified by the Bisection pattern detection method. Then deinterlacing is performed.

Due to the recent advances of digital television (DTV), deinterlacing plays an important role in standard conversion between interlaced and progressive video scanning formats. For an image display of size M×N, where M and N denote the number of scan lines and number of pixels in each scan line, respectively, in an interlaced video scanning format, the picture formed by the stack of all even scan line m=0, 2, 4, . . . , M−2 is called top field (or even field). Each even scan line of the top field is called existing scan line while its odd counterpart whose pixels do not exist is called missing scan line. In a similar fashion, the bottom field (or odd field) is formed by the stack of all odd scan lines m=1, 3, . . . , M−1 which are the existing scan lines in this case. These two fields are displayed in an alternating manner at different time instants to form a complete image on the display.
The object of deinterlacing is to convert each M/2×N field (either top or bottom field) to a complete M×N image by interpolating each pixel in the missing scan lines from its neighboring (above and below) existing scan lines. Let d (in pixel unit) denote the detected direction obtained by the edge direction detection process. Referring to the example in FIG. 3, an interpolation of the missing pixel ƒ[m,n] in the current field f (e.g., field 300) can be calculated by the simple directional linear interpolation 302 which can be expressed as:
                              f                                [                          m              ,              n                        ]                          =                              1            2                                          (                                          f                                                  [                                                            m                      -                      1                                        ,                                          n                      +                      d                                                        ]                                            +                              f                                                  [                                                            m                      +                      1                                        ,                                          n                      -                      d                                                        ]                                                      )                                              (        1        )            where m is the scan line number of the missing pixel, and n is the pixel number in the missing scan line.
In deinterlacing, conventional edge direction detection techniques typically misdetect when direction |d| is large (the very low angle direction). For example, in FIG. 5(b), the edge direction detector may detect the direction d=−3 (or less, i.e. −4, −5, . . . , depending on the chosen vector length in edge direction detector) even though the more suitable direction should be d=½ or 0 (vertical direction).

Method for detecting bisection pattern in deinterlacing


An airfoil assembly includes an airfoil extending away from a platform. One or more cooling circuits are formed through the platform in order to provide cooling of the platform. The cooling circuit may include a downwardly directed inlet receiving cooling air from below the platform. The cooling air is then directed in a direction generally parallel to the outer surface of the platform and through exits formed through the outer surface of the platform. The cooling circuit may optionally include a plurality of pedestals extending from an outer wall to an inner wall of the cooling circuit to increase the rigidity and the cooling function of the cooling circuit.

The present invention relates generally to gas turbine engines and more particularly to a cooling circuit for a platform of a turbine airfoil.
Turbine blades in a gas turbine engine extend outwardly from a turbine blade platform. In operation, the turbine blades are routinely exposed to temperatures well above their material limits. In existing engines, air from the compressor section of the turbine engine is used to cool the blade material. This cooling air is fed to the blade through a series of rotor cavities underneath the blade platform. The cooling air is then injected into the hot mainstream flow through openings in the sealing area.
Without sufficient cooling of the platform, the platform walls may experience creep deformation. High temperature gradients in the platform may result in thermal-mechanical fatigue. Additionally, the high temperatures can cause oxidation of the platforms.

Turbine airfoil platform cooling circuit


A field oxide formation method involving a primary field oxidation, which is carried out at a predetermined low temperature to form a field oxide film having a thickness smaller than a target thickness, and a secondary field oxidation, which is carried out at a higher temperature capable of relatively reducing the occurrence of a field thinning phenomenon, to form the remaining thickness portion of the target field oxide film. The field thinning phenomenon involved in a field oxidation is reduced. The characteristics of a finally produced gate oxide film is also improved. Consequently, the throughput and reliability of semiconductor devices having gate oxide films are improved.

1. Field of the Invention
The present invention relates to a method for forming the field oxide film of a semiconductor device, and more particularly to a method for forming such a field oxide film, which uses different oxidation temperatures at initial and final stages of a field oxidation, thereby preventing a field oxide ungrowth phenomenon and a field thinning phenomenon while achieving an improvement in the characteristics of a finally produced gate oxide film.
2. Description of the Prior Art
A variety of field oxide film formation methods are known. An example of a conventional field oxide film formation method will be described in conjunction with FIGS. 1a to 1e.
FIGS. 1a to 1e illustrate sequential steps of a conventional field oxide film method in which a semiconductor substrate is recessed after the formation of nitride film spacers thereon to form a field oxide film, respectively.
In accordance with this method, a nitride film 13 is first deposited over a semiconductor substrate 11 which has been formed with a pad oxide film 12, as shown in FIG. 1a. The nitride film 13 is then etched at its portion corresponding to a field region by use of an element isolation mask. The etching step is carried out in an overetching manner, so that the semiconductor substrate 11 is recessed to a certain depth, for example, a depth of 50 to 100 .ANG.. Thereafter, a nitride film 14 is deposited over the entire exposed surface of the resulting structure, as shown in FIG. 1b. The nitride film 14 is then dry-etched without using any mask, thereby forming nitride film spacers 14' as shown in FIG. 1c. Using the nitride film spacers 14' as a mask, the exposed portion of the semiconductor substrate 11 between the nitride film spacers 14' is recessed by use of an etch process, thereby forming a hole having a desired depth in the semiconductor substrate 11, as shown in FIG. 1d.
At the silicon etching step for recessing the portion of the semiconductor substrate 11 corresponding to the field region, a portion of the nitride film 13 corresponding to an active region is also partially etched because the etch selectivity of silicon to the nitride film is finite. As a result, a polymer P containing silicon and nitrogen is formed in the hole of the semiconductor substrate 11. The formation of such a polymer is less generated in regions, such as cell regions of a memory device, where the area ratio a of the field region to the active region is relatively small. However, a large amount of polymer P is produced in peripheral circuit regions where the area ratio .alpha. of the field region to the active region is considerably large.
The polymer P formed during the recess silicon etching step is outwardly discharged or left in the hole or valley portion of the field region. In the field region associated with the peripheral circuit region, a relatively large amount of polymer is left on the bottom of the hole. Moreover, the polymer is not simply laid on the bottom of the hole, but embedded to a certain depth in the portion of the silicon substrate exposed in the hole. Accordingly, it is impossible to remove such a polymer using conventional wet cleaning methods.
FIG. 1e illustrates a field oxide film formed in an incompletely grown (namely, ungrown) state when the field oxide film formation method of FIGS. 1a to 1d is used.
As shown in FIG. 1e, when a field oxidation is carried out at a temperature of 1,100.degree. C. just after the processing step of FIG. 1d, namely, in a state in which the polymer P is left on the bottom of the hole in the field region, there is a problem in that a field oxide film is formed in an ungrown state. In FIG. 1e, the field oxide film is denoted by the reference numeral 15.
In order to solve such a problem, various methods have been proposed. One method is illustrated in FIG. 2. In accordance with the method shown in FIG. 2, an additional dry etching step is carried out for the nitride film without using any mask after the etching step for recessing the semiconductor substrate 11, thereby removing the polymer P. When the wet field oxidation is carried out at a temperature of 1,100.degree. C. after the additional dry etching step, a field oxide film is normally grown. Accordingly, the field oxide ungrowth is solved.
In this case, however, a long bird's beak is formed. In other words, the additional dry etching carried out to remove the polymer P also partially removes the nitride film spacers 14'. As a result, it is impossible to suppress a bird's beak penetration during the field oxidation. Due to the additional dry etching step, the manufacturing costs also increase.
Another conventional method for solving the field oxide ungrowth problem is illustrated in FIGS. 3a to 3e. In accordance with this method, a wet field oxidation is carried out after the processing step of FIG. 1d without carrying out the above-mentioned additional dry etching step for the nitride film. FIG. 3a corresponds to the case in which the wet field oxidation is carried out at a temperature of 1,100.degree. C., FIG. 3b shows the case in which the wet field oxidation is carried out at a temperature of 1,050.degree. C., FIG. 3c shows the case in which the wet field oxidation is carried out at a temperature of 1,000.degree. C., FIG. 3d shows the case in which the wet field oxidation is carried out at a temperature of 950.degree. C., and FIG. 3e shows the case in which the wet field oxidation is carried out at a temperature of 900.degree. C.
Referring to FIGS. 3a to 3e, it can be found that a field oxide ungrowth phenomenon occurs in the cases using a field oxidation temperature of 1,050.degree. C. or above whereas a field oxide film 15 is normally grown at a field oxidation temperature of lower than 1,050.degree. C.
This result shows that although the polymer P containing silicon and nitrogen is left after the processing step of FIG. 1d, a normal growth of the field oxide film is achieved when the field oxidation is carried out at a certain temperature or below. That is, although the polymer P is not a material serving as an oxidation barrier, it is thermally activated at a certain temperature or above, so that it is changed into a new, third material capable of serving as an oxidation barrier.
Accordingly, in accordance with the above-mentioned method, it is required to use a field oxidation temperature of 1,000.degree. C. or below in order to change the polymer into a third material, thereby preventing the field oxide ungrowth phenomenon.
FIG. 4 illustrates data about a field thinning phenomenon occurring in the field oxide film structures according to the conventional methods of FIGS. 1a to 1e and FIG. 2, depending on the field oxidation temperature. The field thinning phenomenon is a phenomenon wherein the field oxide film has a reduced thickness in a narrow field region as compared to a wide field region.
It is known that such a field thinning phenomenon is mainly caused by stress accumulated in the field oxide film. Accordingly, the stress existing in the field oxide film should be relieved in order to suppress the field thinning phenomenon. The field oxidation temperature is an important parameter associated with the relief of stress.
Referring to FIG. 4, it can be found that the field thinning phenomenon is more remarkably generated at a lower field oxidation temperature. This is because it is difficult to relieve the stress existing in the field oxide film due to an increased viscosity of the field oxide at a low temperature. For example, in the case using an oxidation window width of 0.20 .mu.m, the thickness of the field oxide film formed at the field oxidation temperature of 1,100.degree. C. is smaller than that at the field oxidation temperature of 950.degree. C. by about 15%.
Consequently, the conventional method involves a problem in that the field oxide film has a reduced thickness in a narrow oxidation window region when a field oxidation temperature of 1,000.degree. C. or below is used, even though it is possible to prevent a field oxide ungrowth at the field oxidation temperature. Where a thin field oxide film is formed, a serious problem associated with an electrical punchthrough phenomenon occurs.
FIGS. 5a and 5b are graphs respectively illustrating test data about characteristics of gate oxide films respectively formed in accordance with the conventional method of FIGS. 1a to 1e or FIG. 2 at different field oxidation temperatures of 950.degree. C. and 1,100.degree. C.
Referring to FIGS. 5a and 5b, it can be found that the gate oxide film formed at a field oxidation temperature of 950.degree. C. exhibits a degradation in the characteristics thereof whereas the gate oxide film formed at a field oxidation temperature of 1,100.degree. C. exhibits superior characteristics. Such results are based on the fact that when a field oxide film is grown at a low field oxidation temperature, it is difficult to relieve the stress existing in the field oxide film due to an increased viscosity of the field oxide, thereby causing the semiconductor substrate to be greatly stressed. Consequently, it is understood that a higher field oxidation temperature is advantageous in terms of the field thinning phenomenon and the characteristics of the gate oxide film.

Method for forming field oxide film of semiconductor device with silicon and nitrogen containing etching residue


A method is provided for recovering at least one platinum group metal from an ore containing the same. The method comprises reducing the particle size of the ore to provide the platinum group metal in a leachable condition following which the ore is subjected to leaching with a sulfuric acid solution maintained at a pH of less than 1 during leaching. The solution contains an amount of a soluble bromide compound at least sufficient to complex the platinum group metal while maintaining an amount of an oxidizing agent dissolved in the solutions at least sufficient to maintain the platinum group metal in an ionic form conducive to forming a soluble bromide complex, thereby dissolving substantial amounts of the platinum group metal.

General speaking, the dissolution and recovery of platinum group metals (PGM's), was thought to be possible only by the use of aggressive chemicals. A well known process is dyanide dissolution or platinum group metals.
Dissolution of platinum group metals with a cyanide solution, e.g., sodium cyanide solution, is relative easy, particularly the dissolution of PGM's in their elemental state to form cyano-complexes that are stable in aqueous solutions. However, if PGM's exist in mineral form, such as in oxide ores, it may be necessary to liberate the precious-metals, for example, by converting them into their elemental states or other soluble form before dissolving them with a cyanide solution.
A disadvantage of cyanide dissolution is that it presents environmental problems and particular care must be taken in disposing of waste solutions. Moreover, cyanides are costly materials which make their use economically undesirable.
Another aggressive chemical employed to dissolve precious metals is aqua regia. Aqua regia insures dissolution of PGM's, because of its high acidity, its high redox potential (due to the presence of nitric acid), and its high concentration of complexing ions (12M chloride ions) for complexing the precious metals.
However, the use of aqua regia has its economic disadvantages because of its unacceptable high reagent use, cost and consumption.
A process has been reported regarding the use of bromine for leaching gold from ores. It was found that a relatively low bromide ion concentration can be used to effect dissolution of elemental gold, for example, 0.1M bromide ions, as compared to the much higher chloride ion concentration (12M chloride ions) required for dissolution with aqua regia.
In this connection, reference is made to an article by Batric Pesic et. al. entitled Dissolution of Gold with Geobrom 3400, Fundamental and Applied Studies, which was delivered at the Proceedings of the 13th IMPI Conference at Montreal Precious Metals 1989.
Geobrom 3400 (which is the trademark of a product of Great Lake Chemical Corporation) is a solution containing about 34% free bromine. According to the aforementioned article, the bromine solution was used to dissolve elemental gold from gold concentrates and electronic scrap. Rotating disc studies were conducted using a rotator, a speed controller, a reactor, and a water bath. A typical experiment comprised a 500 ml solution containing 5 ml/l of Geobrom 3400 at a natural pH at a temperature of 250.degree. C., the stirring being carried out at 500 rpm.
The studies indicated that bromine provided a substantially higher rate of gold dissolution than dissolution with sodium cyanide or thiourea.
The use of bromine for the dissolution of gold is disclosed in another article entitled Leaching and Recovery of Gold From Black Sand Concentrate and Electrochemical Regeneration of Bromine by A. Dadgar et. al. This article was presented before the Society for Mining, Metallurgy, and Exploration, Inc. at Reno, Nev. on Sep. 10-12, 1990. This paper describes the leaching of gold with Geobrom 3400 from very rich black sand concentrate and its subsequent recovery by ion exchange resins and solvent extraction.
Mineralogical examinations of PGM in ores generally reveal native metals, sulphides, tellurides, arsenides and antimonides, etc., associated with base metal sulphides as occlusions, intergrowths and solid solution in gabbroic rocks. In South Africa over 20 PGM minerals have been identified, the most common of which are sperrylite (PtAs.sub.2), cooperite (PtS), braggite ((Pt, Pd, Ni) S), and a Pt--Fe alloy. Braggite, vysotskite (PdS) and Pt-Fe alloys are common in an ore known as the Stillwater ore, while Sudburyite (PdSb) is found in Kambalda and Sudbury ores. In the more oxidized Coronation Hill and alluvial deposits the majority of the PGM is present as native Pt and Pd, sometimes alloyed with Fe, associated with the heavier minerals such as magnetite and milenite.
A particular ore of interest is an oxide ore referred to as The Hartley Complex of the Great Dyke in Zimbabwe. Estimates of the value of all Great Dyke ore bodies indicate that it contains approximately 800 million ounces of platinum and 19 million ounces of rhodium. However, since 9% of the ore is oxidized and cannot be processed with current recovery methods, it is discarded as waste which represents a loss of many millions of dollars.
The ore contains at least one precious metal, especially platinum, selected from the group consisting platinum group metals, gold and silver, some in the elemental form, but usually in the form of a precious metal compound selected from the group consisting of sulfides, arsenides, tellurides, selenides, antimonides, and bismuthinides, or as a ferro-alloy of the precious metal, e.g., Pt--Fe alloy. Other ores include certain gold ores containing carbon, generally referred to as refractory ores.
Because the PGM content of the Hartley ore is quite low, mineralogical investigations were carried out on samples concentrated either by shaking table or heavy liquid separation. Mineralogically, the ore contains PGM'S, silicate gangue minerals, oxides and base metal (BM) sulfides. The ore minerals, making up less than 0.01 vol. % of the ore, constitute silicate gangue minerals with the remainder of the ore made up of oxides and BM sulfides.
The gangue minerals consists primarily of hydrated silicates, talc being the main component. Substantial amounts of tremolite, serpentine and chlorite are present. The mineral oxides comprise iron (II) oxide, ilmenite, chromite and wolframite, while the sulfides comprised pyrrhotite (FeS) , chalcopyrite (CuFeS.sub.2) and pentlandite (FeNiS).
We have discovered a method for the recovery of PGM's from ores of the aforementioned types by simply using a sulfuric acid solution relatively low in halide concentration and of controlled redox potential at least sufficient to convert the precious metal to an ionic form conducive to forming a soluble bromide complex thereof.

Recovery platinum group metals from oxides ores


In an X-ray generating device of the neutral grounding system, to remove an unbalance voltage generated due to difference in impedance of parallel transformer coils of the high voltage transformer and particularly an unbalance voltage involved with difference in impedance above and below the neutral points generated in a metal X-ray tube, a plurality of currents flowing in opposite directions through primary windings of the parallel transformer coils in the high voltage transformer are passed through by or wound around a common toroidal coil or wound around an outer circumference of the toroidal coil at a predetermined ratio of winding number, and the unbalance voltage occurring to the secondary side is cancelled by changing primary current with magnetic behavior.

An image diagnostic apparatus using X-rays is designed to radiate X-rays generated from an X-ray generating device to an object to be examined, and detect and image a dose of X-rays which passes through the object. To generate X-rays from an X-ray tube device, DC high voltage is applied between an anode and a cathode of the X-ray tube device, and thermal electrons generated by heating the cathode to a high temperature are accelerated with DC high voltage and collided with the anode. Accordingly, a high voltage power supply for supplying the DC high voltage between the anode and the cathode is necessary.
As for this kind of X-ray high voltage device, an inverter-type high voltage device is generalized, which is greatly superior in point of device miniaturization and performance. It is currently used in almost all kinds of X-ray image diagnostic apparatus including a general X-ray imaging apparatus, an X-ray imaging apparatus for angiography, an X-ray CT apparatus, and the like.
FIG. 9 shows an example of main circuitry of the inverter-type X-ray high voltage device, in which a voltage supplied from DC power supply 1 is converted into a high-frequency AC voltage in full-bridge inverter circuit 2 having power semiconductor switching elements, e.g. insulated bipolar transistors 21, 22, 23, and 24, this AC voltage is boosted in high voltage transformer 3, converted into a DC high voltage in high voltage rectifier 4, and applied to X-ray tube 5. Primary windings of high voltage transformer 3 are formed such that two primary windings including first primary winding 3a and second primary winding 3b are connected in parallel on the output side of inverter circuit 2 in order to secure current capacity.
Further, secondary windings of high voltage transformer 3 include first secondary winding 3c and second secondary winding 3d. An output voltage of first secondary winding 3c is converted into first DC high voltage Va in first high voltage rectifier 4a and applied between anode 5a and an earth of X-ray tube 5. An output voltage of second secondary winding 3d is converted into second DC high voltage Vk in second high voltage rectifier 4b and applied between cathode 5b and the earth of X-ray tube 5. A negative side of DC voltage output terminals of first high voltage rectifier 4a and a positive side of DC output terminals of second high voltage rectifier 4k are connected in series, and the junction is grounded to the earth. This neutral grounding system is employed in the circuit.
By employing the above-described neutral grounding system, a voltage (tube voltage) between the anode and cathode of X-ray tube 5 can be divided into halves to be applied respectively between the anode and the earth and between the earth the cathode. Accordingly, it becomes easy to secure withstand voltage of the high voltage transformer and the high voltage rectifier. However, in the neutral grounding system, unbalance occurs between first DC high voltage Va and second DC high voltage Vk in some cases, and (1) and (2) listed below are the main reasons:
(1) In a glass X-ray tube and in a metal X-ray tube, difference occurs between Va and Vk due to difference between impedances of two pairs of circuits respectively for obtaining voltage Va applied between the anode and the earth and for obtaining voltage Vk applied between the earth and the cathode (impedance of a first circuit including first primary winding 3a and first secondary winding 3c and impedance of a second circuit including second primary winding 3b and second secondary winding 3d of high voltage transformer 3).
(2) In a metal X-ray tube, difference occurs between Va and Vk due to difference between load impedances respectively applied Va and Vk (impedance between anode 5a and the earth of X-ray tube 5 to which Va is applied and impedance between the earth and the cathode to which Vb is applied). Meanwhile, this phenomenon does not occur in the glass X-ray tube.
For example, in an X-ray device whose maximum tube voltage is 150 kV, the withstand voltage of secondary windings of the high voltage transformer and the voltage of an anode and a cathode to the earth of the X-ray tube can be usually estimated to be 75 kV being the half of the maximum tube voltage. However, because a voltage larger than the rating is applied between the anode and the earth or between the cathode and the earth when the above mentioned unbalance voltage occurs and becomes large, the withstand voltage not only of the X-ray tube but also of the high voltage transformer, the high voltage rectifier, and high voltage parts attaching thereto has to be set higher.
Further, an inner space called creepage distance between the high voltage parts and a housing for containing them also have to be made long in accordance with the withstand voltage. For those reasons, the apparatus is obliged to be made large when the unbalance voltage occurs, which becomes an obstacle to the above mentioned miniaturization. Particularly, it becomes a big obstacle to an X-ray CT apparatus which mounts the X-ray high voltage device on a scanner and which aims at the rapid scan or aims to reduce the number of unit of system.
Japanese unexamined patent publication No.Hei.3-101098 discloses a technique of recognizing and solving the unbalance voltage due to (2) difference in load impedance of the metal X-ray tube. This technique is designed to adjust the unbalance voltage in the metal X-ray tube of the neutral grounding system by switching a reactor of one of the plurality of primary windings of the transformer. The adjustment is done by switching the reactor with a switch while measurement is performed. Therefore, the adjustable range is stepwise and it is necessary to switch the reactor in accordance with the X-ray tube. The above adjustment cannot be performed in the X-ray device on which this X-ray generating device is mounted while the tube voltage is actually applied to the X-ray tube to perform imaging. Accordingly, the adjustment had to be done regularly.

X-ray generator and X-ray CT apparatus comprising same


The present invention relates to a reservoir for storage and use of the liquid or mobile phase of a liquid chromatography system. The reservoir comprises a main chamber for containing the majority of the mobile phase and having a conical base with two apertures and two cavities subtending the apertures and in fluid communication with the main chamber. These cavities are adapted to receive a stirrer and a pump filter and to maintain these devices separate from each other during operation. The structure of the reservoir provides for more rapid and thorough mixing and virtually complete utilization of the mobile phase while minimizing introduction of gaseous phase into the liquid chromatography system downstream from the reservoir.

In its most general sense chromatography is the separation of mixtures of chemical substances into their component parts by chromatography adsorption for analytical purposes. Chromatographic adsorption is the preferential adsorption or differential retention of chemical compounds on the basis of molecular size, charge, hydrophobicity or biospecific affinity by an adsorbent material. Liquid chromatography is a form of chromatography using a liquid as the mobile phase and a solid or a liquid on a solid support as the stationary adsorbent phase. A liquid chromatography system typically includes at least the following elements which are connected together in a manner well known to those of ordinary skill in the field: a reservoir, a pump, an injector, a column, a detector, and a recorder. High performance liquid chromatography ("HPLC") utilizes specific modifications in the design and nature of the column, the column material, the stationary phase, the sample/mobile phase injector, and the chromatographic conditions (e.g. pressure, temperature, flow rate) to provide improved separation and resolution for more refined analysis, as will be appreciated by those of ordinary skill in the field.
The mobile phase reservoir is an integral component of any liquid chromatography system, and is particularly critical in an HPLC system. A reservoir in a liquid chromatography system must be capable of performing several functions. It must at least: (1) store the mobile phase; (2) act as the point from which the mobile phase is pumped into the column via the system's pump; (3) act as the site of mixing of the mobile phase to uniformity; (4) act as a reaction chamber in which adjustments to the mobile phase may be performed; (5) act as the site of degassing of the mobile phase; and (6) act as the site of sparging of the mobile phase.
From the chromatographer's point of view, the ability to rapidly mix the mobile phase to uniformity and the ability to utilize as much of the mobile phase as possible without introducing air bubbles into the system are critical features of a liquid chromatography mobile phase reservoir. The known reservoirs for use in a liquid chromatography system are either (1) flat-bottomed reservoirs, (2) reservoirs having a conical base and a single cavity subtending the conical base, or (3) reservoirs having a conical base similar to the Kontes reservoir but terminating in a 1-2 inch diameter flat surface rather than a cavity. In operation a stirrer is placed within the reservoir for mixing the mobile phase to uniformity. In addition, a pump inlet filter is also placed inside the reservoir for removing the mobile phase, and often a sparging device is also inserted to allow for helium sparging. The flat-bottomed reservoirs do not have any cavities, and while they provide good mixing, they require extra care in use in order to avoid interference with the stirrer by the pump inlet filter and the sparging device. Furthermore, these reservoirs must be tilted in order to utilize as much mobile phase as possible, and this procedure is dangerous when volatile or toxic chemicals are used as the mobile phase. Moreover, when the liquid level in these reservoirs falls low enough to expose some of the pump inlet filter to the air or gaseous phase in the reservoir, air bubbles will enter the tubing leading to the pump. Air bubbles cause problems for the pump valves and for the detection downstream from the HPLC column, and are incompatible with an efficient HPLC system.
The known reservoirs having the conical base and a single cavity increase the amount of the mobile phase removed from the reservoir (without resorting to dangerous tilting) compared to the flat-bottomed reservoirs. However, a significant drawback is that mixing is minimal. In these single cavity reservoirs, the cavity holds both a magnetic stirrer and a pump inlet filter. One disadvantage of this single cavity design is that only minimal mixing action for the mobile phase is achieved, even at high stirrer rpms (e.g., 1000 rpm), due to interference from the pump inlet filter and due to the spatial separation of the stirrer from the majority of the mobile phase located in the main chamber of the reservoir. This spatial separation or distance between the majority of the mobile phase and the stirrer is caused by the position of the stirrer at the bottom of the cavity under the inlet filter. For example, a pH adjustment in a typical conical, single cavity reservoir can take 30-60 minutes. Eliminating the cavity but retaining the conical base overcomes the spatial separation problem and improves mixing, but the pump inlet filter must be positioned high up enough on the conical slope to avoid interference with the stirrer. This inlet filter position increases the volume of mobile phase that cannot be pumped out of the reservoir without introducing air bubbles into the system.


Disclosed are blends of polystyrene and at least one of syndiotactic polypropylene, ethylene propylene copolymers, and styrene-butadiene-styrene triblock copolymers. These blends are prepared using solution polymerization and have unique morphologies and desirable physical properties. The blends can also be prepared with graft-promoting or crosslinking agents and rubbers to prepare modified high impact polystyrene.

1. Field of the Invention
The present invention relates polystyrene blends. The present invention particularly relates to polystyrene blends prepared using a solution blend process.
2. Background of the Art
Polystyrene is one of the largest volume thermoplastic resins in commercial production today. Unmodified polystyrene is well suited to applications where its brittleness is acceptable. Engineering plastics have been used in applications where less brittleness is required, but such polymers are often expensive or have properties other than less brittleness that make them less than optimum selections. Thus, styrene-based copolymers, and particularly polystyrene resins that are modified with organic rubber particles, have been investigated for use in applications requiring less brittleness. The modification of polystyrene to reduce brittleness is often referred to increasing its impact properties and thus the modified polystyrene is said to have higher impact.
These high-impact polystyrene blends, commonly referred to by the acronym HIPS, are known to be useful in the art of preparing articles with polymers wherein the application for the articles requires less brittleness than unmodified polystyrene. For example, U.S. Defensive Publication T59,011 to Smith discloses that a high impact resin can be prepared by blending from 15 to 50 parts of an impact modifier with from 85 to 50 parts of a clear crystal polystyrene. Such materials are disclosed to be useful for packaging applications.
Another method of making HIPS is to first dissolve a rubber in styrene monomer and then polymerize the monomer. Such polymers are disclosed in U.S. Pat. No. 6,569,941 to Sosa, et al. Therein, it is disclosed that styrene monomer containing a dissolved polybutadiene rubber is flowed into an elongated upflow stirred reactor containing three reaction zones, wherein the styrene monomer is polymerized to form a HIPS.
It is also known to blend polystyrene with other materials. For example, U.S. Pat. No. 5,194,525, to Miura et al, discloses a continuous process for making polystyrene from styrene monomer and a polymerizable unsaturated fatty acid. The inclusion of the unsaturated fatty acid is disclosed to improve the heat resistance and moldability of the blend, making the modified polystyrene desirable for injection molding applications.
In HIPS, desirably the polystyrene is a continuous phase including a discontinuous phase of rubber particles. The size and distribution of the rubber particles in the continuous polystyrene phase can affect the properties of the HIPS. In blends of polystyrene with other materials, the distribution of the noncontinuous phase in the continuous polystyrene phase is often similarly important.

Polystyrene blends and a method of making same


Device and method for performing an atherectomy. The device utilizes a dual lumen catheter, with a guide wire being receivable in one of these lumens, and a flexible, elongated drive shaft carrying an abrasive burr at its distal end being disposed in the other lumen. The drive shaft and abrasive burr each include a central lumen so that they can be advanced over a positioning wire. The positioning wire has a generally straight proximal portion, and a distal end that is slidably secured to the guide wire so that the positioning wire can be moved proximally and distally with respect to the guide wire. The positioning wire also includes a distal end portion with a burr positioning segment. The burr positioning segment has a predetermined curved shape so that when the abrasive burr is advanced over the positioning wire to a position along the curved burr positioning segment, the burr positioning segment positions the burr laterally away from the guide wire, thus giving control over the lateral position of the burr within an artery. The device therefore allows selective removal of tissue from one side of an artery, permitting selective treatment of eccentric stenotic lesions without damaging the artery wall, and permitting treatment of lesions generally without blocking blood flow through the artery during use of the device.

A variety of techniques and instruments have been developed for use in the removal or repair of tissue in arteries and similar body passageways. A frequent objective of such techniques and instruments is the removal of atherosclerotic plaques in a patient's arteries. Atherosclerosis is characterized by the buildup of fatty deposits (atheromas) in the intimal layer (under the endothelium) of a patient's blood vessels. Very often over time, what initially is deposited as relatively soft cholesterol-rich atheromatous material hardens into a calcified atherosclerotic plaque. Such atheromas restrict the flow of blood, and therefore are often referred to as stenotic lesions or stenoses, the blocking material being referred to as stenotic material. If left untreated, such stenoses can cause angina, hypertension, myocardial infarction, strokes and the like.
Several kinds of atherectomy devices have been developed for attempting to remove some or all of such stenotic material. In one type of device, such as that shown in U.S. Pat. No. 5,092,873 (Simpson), a cylindrical housing, canned at the distal end of a catheter, has a portion of its side-wall cut out to form a hollow housing into which the atherosclerotic plaque can protrude when the device is positioned next to the plaque. An atherectomy blade, disposed within the housing, is then advanced the length of the housing to lance the portion of the atherosclerotic plaque that extends into the housing cavity. While such devices provide for directional control in selection of tissue to be excised, the length of the portion excised at each pass of the atherectomy blade is necessarily limited to the length of the cavity in the device--in turn, the length and relative rigidity of the housing limits the maneuverability and therefore the utility of the device in narrow and tortuous passageways such as coronary arteries.
Another approach which solves some of these problems involves the use of a rotating burr covered with an abrasive cutting material such as diamond grit (diamond particles or dust) carried at the distal end of a flexible drive shaft, similar to a dental abrading/polishing tool. Examples of such devices are illustrated in U.S. Pat. No. 4,990,134, (issued to Auth), as well as "Premier Two Striper.RTM. Gingival Curettage" (Abrasive Technology, Inc. 1982); "Premier Two Striper.RTM. Crown & Bridge Techniques" (Abrasive Technology, Inc. 1981); H. Gilmore, et. al, operative Dentistry (C. V. Mosby Company 1982, 4th ed.), pp. 64-65, 69, 348-350; R. Tupac, et al., "A Comparison of Cord Gingival Displacement With the Gingitage Technique," Journal of Prosthetic (Nov. 1981, pp.509-515); and Premier Presents Two Striper.RTM. Dental Diamond Instruments (Abrasive Technology, Inc. 1989). The burr in such devices is rotated at speeds in the range of 20,000 to 200,000 rpm or more, which, depending on the diameter of the burr, can provide surface speeds of the abrasive particles on the burr above or below 40 ft/sec. Auth claims that at surface speeds below 40 ft/sec the abrasive burr will remove hardened atherosclerotic material but will not damage normal elastic soft tissue of the vessel wall. Auth also admits that at surface speeds above 40 ft/sec the abrasive burr will remove both hardened and soft tissue. See, e.g., U.S. Pat. No. 4,990,134 at col. 3, lines 20-23. Unfortunately not all atherosclerotic plaques are hardened, calcified atherosclerotic plaques. Moreover, the mechanical properties of the soft plaques are very often quite close to the mechanical properties of the soft wail of the vessel. Thus, one cannot safely rely entirely on the differential cutting properties of such abrasive burrs to remove atherosclerotic material from an arterial wall, particularly where one is attempting to entirely remove all or almost all of the atherosclerotic material. See, e.g., Atherectomy, A Physicians Guide, (Strategic Business Development, Inc., 1990), pp. 89, 94-96. Furthermore, the Auth burr effectively blocks blood flow through the artery during the passage of the burr through the stenosis, thus limiting the amount of time of each pass across the stenosis to less than one minute (and perhaps as little as 10 seconds). See id. at pp. 95-96. Because the size of the particles removed by the Auth burr is very small (typically 5 microns or less), and because of the time limitations described above, in clinical practice, in order to remove a sufficient amount of tissue during each pass of the burr across the stenosis, the Auth burr is virtually always rotated at speeds of at least about 155,000 rpm. At such speeds a diamond dust covered burr with a diameter of 1.5 mm achieves a surface speed of 40 ft/sec, the very speed at which the differential cutting effect becomes limited, at best (i.e., the burr removes both hard and soft tissue).
The ability of diamond dust covered burrs to remove human soft tissue at high surface speeds (e.g., small diameter burrs rotated at about 200,000 rpm) has been known for some time and has been utilized in dentistry since at least the early 1980's to remove soft gum tissue (see, e.g., "Premier Two Striper.RTM. Gingival Curettage" (Abrasive Technology, Inc. 1982); "Premier Two Striper.RTM. Crown & Bridge Techniques" (Abrasive Technology, Inc. 1981); H. Gilmore, et. al, Operative Dentistry (C. V. Mosby Company 1982, 4th ed.), pp. 348-350; R. Tupac, et al., "A Comparison of Cord Gingival Displacement With the Gingitage Technique," Journal of Prosthetic Dentistry (Nov. 1981, pp.509-515).
Several problems have been recognized in use of the Auth-type of burr, however. First, although under some conditions the differential cutting properties of such burrs are effective to protect healthy tissue, in many circumstances the burr nevertheless can abrade at least a portion of the healthy tissue, creating a risk of perforation. This is particularly true at higher rotational speeds. A majority of atherosclerotic lesions are asymmetrical (i.e., the atherosclerotic plaque is thicker on one side of the artery than on the other). Moreover, pressure of the burr against the atherosclerotic plaque is achieved only by the use of a burr having a diameter slightly larger than the opening through the stenotic passageway. Thus, since the stenotic material will be entirely removed on the thinner side of an eccentric lesion before it will be removed on the other, thicker side of the lesion, during removal of the remaining thicker portion of the atherosclerotic plaque the burr necessarily will be engaging healthy tissue on the side which has been cleared--indeed, lateral pressure by such healthy tissue against the burr is required to keep the burr in contact with the remaining stenotic tissue on the opposite side of the passageway. For stenotic lesions that are entirely on one side of an artery (a relatively frequent condition), this means that the healthy tissue across from the stenotic lesion will be exposed to and in contact with the abrasive burr for substantially the entire procedure. Moreover, pressure from that healthy tissue against the burr will be, in fact, the only pressure urging the burr against the atherosclerotic plaque. Under these conditions, a certain amount of damage to the healthy tissue is almost unavoidable, even though undesirable, and there is a clear risk of perforation. Thus, in clinical practice (balancing safety and residual stenosis), physicians rarely use a burr diameter of more than 2 mm, even on patients where the original diameter of the coronary artery lumen is estimated to be 3 mm. See, e.g., Atherectomy, A Physicians Guide, (Strategic Business Development, Inc., 1990), p. 96. These risks are enhanced at high rotational speeds where the differential cutting phenomenon is significantly diminished.
As indicated above, in clinical practice the opening of the stenosis of coronary (heart) arteries is performed very fast and thus very large numbers of small particles of stenotic material (estimated to be 1,000,000 per cubic mm of stenotic material removed--see id. at p. 92) are released into the coronary artery within a very short period of time. Although individually the particles (typically in the range of 5 microns) can easily pass through the capillaries, when such large numbers of such particles are released within a very short period of time it is very possible that there is a risk that they may at least temporarily occlude the capillaries. This may explain the heart pain which is not infrequently experienced by patients immediately after the Auth-type burr is passed across the stenosis, as well as elevated levels of enzymes indicative of myocardial ischemia (such as CPK) which have been documented in some patients after the Auth-type burr procedure. See id. at p. 95. There is yet a further disadvantage to the traditional rotating burr apparatus, particularly the device depicted in the '134 Auth patent. When such a device is used to open an arterial passageway which is quite narrow, the burr utilized must initially be relatively small. When the small-sized burr has been completely advanced through the stenosis, however, it cannot widen the passageway to a diameter larger than the diameter of the burr itself, and the burr must be exchanged for a larger diameter burr to continue the widening process. It is not unusual, and in fact is quite common, that at least two, and sometimes three or four progressively larger burrs are necessary to complete the task. Since the burrs are permanently attached to the flexible drive shaft, which in turn is permanently attached to the drive motor (or air turbine) and the associated proximal controls for the device, changing burr sizes means essentially exchanging the entire device (except for the guide wire) for a new one. Currently the cost of such devices is quite high, and the need to use multiple burr sizes multiplies this cost, making the procedure quite expensive.
It would therefore be advantageous to provide an abrasive burr based instrument which can provide directional control of removal of stenotic tissue allowing one to effectively remove eccentrically located stenotic material (e.g., atherosclerotic plaque) without any risk of damage (and thus risk of perforation) to normal vascular wall not covered with stenotic material. It would also be advantageous to provide such an instrument that would not completely occlude the blood flow through an artery during the atherectomy procedure, thus, not limiting the time available to the physician to open the stenosis. Furthermore, it would be advantageous to provide such an instrument that would allow slower, controlled release of particles of stenotic material into the capillaries over a longer period of time, thus reducing or eliminating the possibility of temporary cardiac ischemia (as evidenced by CPK elevation) and heart pain associated with passage of the burr across the stenosis. Also, it would be advantageous to provide a small diameter burr-based instrument capable of opening stenoses in large diameter peripheral arteries (such as the femoral and iliac arteries) without resorting to entry through a cut-down on the femoral artery. Finally, it would be extremely advantageous to provide such a device that can accomplish these objectives and also allow one to widely open stenotic vessels (e.g., atherosclerotic arteries) to their large original diameter without having to use multiple burrs of successively larger diameters, thus reducing the number of very expensive instruments needed for each procedure.

Device and method for directional rotational atherectomy


Inflammatory dermatoses are controlled and cleared by topical application to the affected areas of the skin of a composition containing both a corticosteroid and a retinoid. The combined therapy is more effective than either active ingredient alone and is particularly effective for chronic dermatoses which are or have become resistant to corticosteroid treatment alone. After clearing has been obtained with once or twice daily applications of the corticosteroid-retinoid composition, usually after several weeks, clearance can be maintained by less frequent application or lower concentrations of the composition or by application of only one of the corticosteroid or retinoid, less potent corticosteroids, or other non-steroidal therapies, depending upon the particular dermatosis being treated.

The most widely prescribed drugs to treat dermatologic disease are corticosteroids, also known as glucocorticosteroids or glucocorticoids. Approximately 50% of prescriptions written by dermatologists are for topical corticosteroids. Since the introduction of these substances in the early 1950s for dermatologic diseases, topical corticosteroid therapy continues to be the mainstay for the management of a broad spectrum of inflammatory dermatoses. Although systemic corticosteroids are often required in some severe dermatologic diseases, topical treatment is preferred in most responsive cases because it causes fewer systemic adverse effects.
Topical corticosteroids are generally effective in the treatment of acute and chronic dermatoses such as seborrheic dermatitis, atopic dermatitis, contact dermatitis of the irritant and allergic type, localized neurodermatitis (lichen simplex chronicus), lichen planus, and psoriasis. Steroids are also used for a variety of other less common conditions, such as Darier's disease and ichthyosiform dermatitis. A good overview of topical corticosteroid therapy appears in a series of papers presented at the Symposium on Topical Corticosteroids Today and Tomorrow, sponsored by Schering AG in Bali, Jun. 16-20, 1988, which were published in Drugs 36, Supplement 5, pp. 1-61 (Adis Press Ltd. 1988).
Individual topical corticosteroid preparations vary in anti-inflammatory potency and clinical efficacy. Therapeutic efficacy of steroid therapy can often be enhanced by increasing the potency of the steroid or by using special enhancers, such as occlusive dressings. In general, efficacy is dependent on multiple factors, viz. vehicle, site and frequency of application, disease, the individual patient, use of occlusive dressings, etc.
Potency of the corticosteroid preparation varies according to the particular corticosteroid selected, its concentration, and its vehicle. For convenience, topical corticosteroids, are classified into seven groups from most (Group I) to least (Group VII) potent as shown, for example, in Table I below. Further, these classifications are ranked according to relative potency designations with Group I usually designated as ultra high potency, Groups II and II designated as high potency, Groups IV and V designated mid potency, and Groups VI and VII designated low potency. Representative commercial corticosteroid preparations are set forth and classified according to this system in R. B. Stoughton, "Percutaneous Absorption of Drugs," Annual Review of Pharmacologic Toxicology, pp. 55-69 (1989).
TABLE I __________________________________________________________________________ POTENCY RANKING OF TOPICAL CORTICOSTEROIDS (Group I, most potent to Group VII, least potent) Group Usual Potency Generic Name Dosage Form Concentration __________________________________________________________________________ I. Betamethasone dipropionate cream, ointment 0.05% Clobetasol propionate cream, ointment 0.05% Diflorasone diacetate ointment 0.05% II. Amcinonide cream, ointment 0.1% Betamethasone dipropionate ointment 0.05% Diflorasone diacetate ointment 0.05% Halcinonide cream, ointment 0.1% Fluocinonide cream, ointment, solution, gel 0.05% Desoximetasone cream, gel, ointment 0.05%-0.25% Triamcinolone acetonide cream, ointment 0.5% Mometasone ointment 0.1% Fluocinolene acetonide cream 0.2% III. Triamcinolone acetonide ointment 0.1% Betamethasone dipropionate cream 0.05% Diflorasone diacetate cream 0.05% Betamethasone valerate ointment 0.1% Mometasone cream 0.1% IV. Flurandrenolide ointment 0.05% Triamcinolone acetonide cream, lotion 0.1% Fluocinolone acetonide ointment 0.025% Desoximetasone cream 0.05% Clocortolone pivalate cream 0.1% V. Flurandrenolide cream 0.05% Betamethasone dipropionate 0.05% Triamcinolone acetonide lotion 0.1% Hydrocortisone butyrate cream, ointment 0.1% Fluocinolone acetonide cream 0.025% Betamethasone valerate cream 0.1% Hydrocortisone valerate cream 0.2% VI. Desonide cream, ointment 0.05% Fluocinolone acetonide solution 0.01 Betamethasone valerate lotion 0.05% Aciometasone dipropionate cream, ointment 0.05% VII. Topicals with hydrocortisone, dexamethasone, flumethalone, prenisolon e, and methyprednisolone __________________________________________________________________________
Though some steroids, particularly mid- to high-potency steroids, are efficacious in chronic dermatoses, long term use of steroids is associated with serious local side effects. These include skin atrophy (thinning, telangiectasia, striae) and a prompt rebound flare when the steroid is stopped. Treatment of large areas of skin and use of occlusive dressings can also increase the potential for adverse effects. This is especially the case in children. As discussed more fully below, U.S. Pat. Nos. 4,889,847 and 5,019,569 disclose the use of retinoids, such as tretinoin, to prevent and reverse skin atrophy induced by corticosteroid therapy.
Topical retinoids such as tretinoin (all-trans-retinoic acid or Vitamin A acid) have been used by dermatologists for almost twenty years. For example, tretinoin is used topically in the treatment of acne vulgaris, primarily grades I-III, in which comedones, papules, and pustules predominate. See, for example, U.S. Pat. No. 3,729,568 of Kligman.
Tretinoin has been used effectively in the treatment of other skin conditions such a psoriasis, congenital ichthyosiform erythroderma, Darier's disease, epidermolytic hyperkeratosis, actinic keratosis, trichostasis, flat warts, basal cell carcinomas, and a variety of unrelated disorders. See, for example, J. R. Thomas et al. "The Therapeutic Uses of Topical Vitamin A Acid," Journal of the American Academy of Dermatology, 4:505-513 (1981).
More recently, it has been found that retinoids, such as tretinoin, particularly when used in separate, sequential topical applications with the corticosteroid, prevent and reverse skin atrophy in patients on long term corticosteroids for various skin diseases. See, for example, U.S. Pat. Nos. 4,889,847 and 5,019,569 of Kligman, Mezick and Capetola, the disclosures of which are incorporated herein by reference. However, that work was concerned with preventing and reversing the side effects of corticosteroid therapy and did not address the possibility of enhanced efficacy, especially for those patients whose disease has become resistant to corticosteroids. Dermatologists call this acquired resistance "tachyphylaxis" and try to mitigate it by various strategies, such as rest periods (interval therapy) and switching to another drug. These approaches are only marginally helpful.

Methods of treating inflammatory dermatosis


A clamping device which holds a workpiece at a predetermined position during a machining operation of the workpiece comprises a clamper for clamping a workpiece, a feed device for moving the clamper in the axial direction, a load sensor which is fixed to the clamper and detects a clamping force acting on the workpiece, and a memory in which a target clamping force corresponding to the shape of the workpiece and a method of machining operation is stored. The control device compares the clamping force detected by the load sensor with the target clamping force stored in the memory and controls the clamper in response to the deviation between the detected clamping force and the target clamping force. The clamping device also has a position detecting means for detecting the axial position of the clamper. The control device compares the present position detected by the position detecting means with a stop position which is detected during the initial clamping and is stored in the memory, and controls the clamper in proportion to the deviation between the detected position and the stored stop position.

1. Field of the Invention
The present invention relates to a clamping device for holding a workpiece at a predetermined position during a machining operation of the workpiece.
2. Discussion of the Prior Art
Holding a workpiece at a predetermined position with a predetermined clamping force is important for raising machining accuracy of the workpiece. Many kinds of clamping devices are used according to shapes of workpieces and machining methods. A clamping device generally used has a hydraulic cylinder by which a clamper is moved so as to hold the workpiece at a predetermined position. Since the pressure of oil used for moving the clamper is set to a constant level, it is impossible to select a suitable clamping force according to the shape of a workpiece and the machining method, thereby the machining accuracy of the workpiece tends to decrease. Further, in the event that many kinds of workpieces are machined, it is difficult to properly hold all kinds of the workpieces because each kind of workpiece requires a different clamping force.
To solve the above-mentioned problems, a clamping device having accumulators and a switching valve has been proposed as is disclosed in Japanese Laid-Open Patent Publication No. 63-84833. Oils having different pressures are filled in the respective accumulators. When an operator or a command from a numerical controller operates the switching valve, oil from a selected accumulator is supplied to the cylinder for advancing the clamper. Therefore, the clamping force of the clamper can be changed according to the shape of a workpiece and the machining method.
However, even in the above-described construction, the clamping force of the clamper is merely changed to one of two different clamping forces. It is therefore difficult to hold the workpiece with a suitable clamping force. Further, there is a problem that a plurality of accumulators, pipes and the switching valve require a large space. Furthermore, the use of oil needs a pump which would generate noises and heat.


A switching power conversion circuit comprises a saturable load assembly, a first switching inductance coil assembly and a second switching inductance coil assembly. The saturable load assembly is composed of a load and a saturable reactor. The first switching inductance coil assembly is connected to the saturable load assembly and a first potential. The second switching inductance coil assembly is magnetically coupled with the first switching inductance coil assembly, and is connected to the first switching inductance coil assembly and a second potential. When the first and second switching inductance coil assemblies are power switched, the saturation effect of the saturable reactor is exploited to let the terminal potential of the saturable reactor drop before switching, hence letting the terminal potential of the transfer switch be zero.

For high-efficiency switching power converter, because the whole load current will flow through a switch when switching, the switch has to bear a very high switching stress and a high switching loss proportional to the switching frequency, zero voltage switching is a very important technique.
Besides, time-varying current and time-varying voltage caused by high-speed switching will result in serious electromagnetic interference (EMI).
In order to reduce the size and weight of a converter and enhance its power density, it is necessary to increase its switching frequency, which will more deteriorate the drawbacks of the switching converter. If the voltage of the switch can be made zero at the instant of switching, the above drawbacks can be improved. Therefore, how to reduce the switching loss, the switching stress and EMI of a switching converter is a very important problem to be urgently solved in this industry.
FIG. 1A shows a conventional voltage-drop type resonance converter having zero voltage switching. This kind of converter makes use of a resonance capacitor in shunt with a switch to produce a zero voltage so that zero voltage switching can be accomplished for the switch.
Although the above zero voltage switching technique can reduce the switching loss generated when switching due to zero voltage switching, the resonance circuit will cause a large number of tank currents, which will cause transmission loss in the circuit. This transmission loss will seriously affect the supply and transmission of power to lower the conversion efficiency of the power source.
Accordingly, the present invention aims to provide a switching power conversion circuit, which not only can accomplish zero voltage switching with a simple circuit to lower the switching loss, but also can diminish the generation of tank current to greatly lower the transmission loss.

Zero voltage switching power conversion circuit


A system and method for use in an implanted cardiac pacing device, whereby an optimal AV delay is determined at or near lower rate (pacing) limit (LRL) by determining measuring the variance, or instability, of the QT interval for a set of intervals. In one embodiment, asynchronous “LRL pacing” with a first programmed AV delay determines a measure of QT variance. The difference between the maximum QT and the minimum QT is expressed as QT difference (QTD). For each programmed AV delay the QT variance is again measured and the optimal AV delay produces minimum QTD. In another embodiment, AV delay is modulated around base values for a time. The difference between QT for the modulated AV and for the base AV (dQT) is measured at each base value, and the optimal AV delay corresponds to the smallest dQT.

The advantages of dual chamber synchronous pacing are well recognized in the art. Pacemakers that can operate in one or more synchronous modes are able to take advantage of the heart's natural atrial, or sinus-activated, depolarizations. This allows the atrium to control the ventricular response rate where appropriate, and offers the improvement in ejection fraction that results from synchronizing the ventricular pacing stimulation with the atrial contraction. Prior studies have shown that the improvement in ventricular output due to synchronous pacing is most pronounced at relatively low heart rates. At higher heart rates the increase in cardiac output is largely due to the increased rate of contractions, but at lower rates there is a significant increase in efficiency that results from synchronous action. Accordingly, while the AV interval can be controlled to vary with rate, the most important value of the AV=f(r) curve is the lower rate limit (LRL). Available modes of pacing that provide synchronous pacing include VDI, VDD, DVI, DDD and DDD as well as rate-responsive variations thereof, among others.
The pacemaker art has also come to include multi-mode designs having the capability to which modes in response to changing patient conditions. Most dual and multi-chamber pacemakers are programmable to distinct modes, or are configured to switch automatically from one mode to another under certain prescribed conditions. See, for example, U.S. Pat. No. 4,527,568 and U.S. Pat. No. 4,920,965. But as a general rule it is advantageous to operate in a synchronized mode as much as possible wherein an atrial sense (AS) or delivered atrial pace pulse (AP) is followed (in the absence of a natural ventricular contraction) by a ventricular pace pulse (VP) that is timed to occur at a predetermined AV interval, or delay following the atrial event.
It is known that it is desirable to optimize the AV delay (AV), and also to set AV as a function of rate. See U.S. Pat. No. 5,330,511, Boute, assigned to the assignee of this invention and incorporated herein by reference in its entirety. The prior art shows a number of examples of pacemakers that attempt to adjust AV as a function of a sensed variable. See U.S. Pat. No. 4,303,075, wherein AV delay is modified in accordance with a sensed measure of stroke volume. U.S. Pat. No. 5,713,930 discloses setting AV delay by monitoring QT interval at different values of AV to determine the AV delay that corresponds to ventricular fusion, and then setting AV to a value just less than that corresponding to fusion. The pacemaker of the above-mentioned Boute patent optimizes AV by monitoring QT interval (QT) at different values of AV while pacing at LRL, and selecting the AV that corresponds to the longest QT. The following Table 1 lists patent references relating to the subject matter of this invention:
TABLE 1PATENT NO.INVENTOR(S)ISSUE DATEU.S. Pat. No. 4,303,075Heilman et al.Dec., 1981U.S. Pat. No. 5,330,511BouteJul. 19, 1994U.S. Pat. No. 5,534,016BouteJul. 9, 1996U.S. Pat. No. 5,560,368BergerOct. 1, 1996U.S. Pat. No. 5,713,930ven der Veen et alFeb. 3, 1998
All patent references listed in Table 1 above are hereby incorporated by reference in their respective entireties. As those of ordinary skill in the art will appreciate upon reading this Summary of Invention, Detailed Description and claims as set forth below, many of the devices and methods disclosed in the references of Table 1 may be modified advantageously by using the teachings of the present invention.
The above-listed U.S. Pat. No. 5,330,511 purports to base AV optimization on examining QT behavior at different AV intervals. This technique involves finding a value of QT at each AV test value, and selecting as optimal the AV that corresponds to the longest QT. See FIG. 6A for a representation of this aspect of the prior art. However, this test depends upon finding a stable QT at each AV test value, and this is difficult in practice. This reference notes that a three-minute waiting period is required after each change to a new AV level in order to let QT stabilize, and that fact alone makes for a lengthy test where up to 12 different AV values are tested. Further, it has been found that the QT interval remains sufficiently unstable even after three minutes to enable finding a value of QT precisely enough to be able to compare the QT values corresponding to different AV test values and determine which one is the maximum QT. Such instability may be the result of slow catecholamine feedback or other mechanisms. Thus, while the optimum value of AV is indeed that where QT is a maximum, in practice this is difficult to measure.
There thus remains a need in the art for a more reliable and precise method for measuring optimum AV interval for use in an implanted cardiac pacing device. There is a need for an improved system and method of periodically determining the optimum relationship between AV interval and pacing rate for a patient at one or more low pacing rates, and for making this determination reliably and in much less time than prior art methods. Also, it is desirable to utilize a parameter such as QT, or another measure of PQRST cardiac-cycle signals to obtain the needed information, so that no extra sensor has to be employed.

Synchronous pacemaker with AV interval optimization


An action figure toy may include a base, an action figure, and a flipping mechanism disposed on the base. In some embodiments, the action figure toy may include at least two cords suspended from the base, and the action figure may be configured to ascend the at least two cords toward the base by manipulation of the at least two cords by a user. The flipping mechanism may be configured to engage the action figure when the action figure ascends to the flipping mechanism. The flipping mechanism may enable the action figure to rotate about an axis that is transverse to a line parallel to at least a portion of at least one of the at least two cords when the flipping mechanism engages the action figure.

Examples of toys or devices for ascending strings or ropes are disclosed in U.S. Pat. Nos. 240,510, 1,211,479, 1,332,601, 1,961,081, 2,064,119, 2,550,065, 2,565,096, 2,766,551, 3,179,994, 3,393,470, 3,852,943, 4,056,896, 4,253,219, 4,302,902, 4,576,586, 4,881,622, 5,320,572, 5,727,981, 5,743,781, and 6,132,285, and in German Patent No. DE 404,240. The disclosures of these and all other publications referenced herein are incorporated by reference in their entirety for all purposes.