Disclosed is a single basin, fill and draw wastewater treatment apparatus and method having a unique influent delivery manifold which delivers the incoming influent into a first zone that prevents hydraulic turbulence or short circuiting of un-treated influent from degrading the effluent quality during the decant phase of its cycle while continuously accommodating influent flows and reduces the internal hydraulic velocities to a slow enough rate to utilize the settling sludge blanket as a natural biological filter to absorb and treat influent flows during the air/off phase of its cycle.

U.S. patent application Ser. Nos. '860 and '113, the disclosures of which are incorporated herein by reference, discloses and claims an improved wastewater treatment process referred to as I.D.E.A. "C.F.C.R." which is an acronym for "Intermittent Decant Extended Aeration Continuous Feed Cyclic Reactor" and incorporates CONTINUOUS FEED activated sludge technology with intermittent CYCLIC system operation requiring only a SINGLE BASIN. The system uses a single tank (reactor basin), preferably made of fiberglass in which the activated sludge is aerated over a number of pre-determined cycles. Solid/liquid separation occurs during the air-off cycle. Treated effluent is decanted or withdrawn from directly below the liquid surface. Influent inflow is continuously accommodated at all times. In this way the function of flow equalization, biological oxidation, nitrification, denitrification, secondary sedimentation and aerobic sludge digestion are all carried out in a single vessel. The duration of a cycle is specific to each design application and variable in the field as required.
The Continuous Feed Cyclic Reactor (C.F.C.R.) Process of the I.D.E.A. System combines SBR, ICEAS, and Continuous Flow Activated Sludge and Extended Aeration Principles. It is a fill and draw system which accommodates continuous feed (influent) to the tank (reactor basin). The heart of the process lies in the activated sludge blanket which reduces the BOD5 (biological oxygen demand) and TSS (total suspended solids) and removes nitrogen and phosphorous in the absence of polymers or filters. Food to microorganism ratios (F:M) may vary from 0.04 to 0.3 lb. of BOD5 /lb of MLSS/DAY and mixed liquor suspended solids (MLSS) design concentrations range from 1,000 to 15,000 mg/l. Actual practice has shown MLSS concentration in the 2,000 to 8,000 mg/l range to be most effective. With a hydraulic retention time (HRT) targeted for 18-36 hours and a sludge age (SRT) of at least 20 days. The Intermittent Decant Extended Aeration (I.D.E.A.) system is sized according to extended aeration standards. With such design parameters, typical excess solids (waste sludge) production ranges from 0.5 to 1.0 LB/LB of BOD5 removed. The sludge produced is quite stable with an O2 uptake rate of less than 10 mg/l O2/gm MLSS/hr.
One of the major process advantages of the Intermittent or Cycled Extended Aeration Process (EPA Design manual "0n Site Waste-Water Treatment and Disposal Systems", October 1980.) used in the I.D.E.A. System is that it provides nitrification/denitrification in addition to carbonaceous BOD5 reduction and solids removal without the addition of methanol as an organic carbon source. In addition, denitrification enhances alkalinity recovery. This prevents a PH drop which could contribute to filamentous growth and bulked sludge. Alkalinity recovery is particularly advantageous in regions of low natural alklinity.
It is this unique cyclic process which allows the I.D.E.A System to accomplish nitrification and denitrification. During aeration, biological oxidation and mixing occur. Blower sizing typically provides for 1.4 to 1.6 LBS. of O2/LB of BOD applied/day. For very low strength waste, 20 SCFM/1000 cubic feet reactor volume is provided for mixing. During aeration, excess oxygen is present, and Nitrosomonas sp. oxidize the Ammonia Nitrogen (N/NH3) to Nitrite Nitrogen (N/NO 2). Nitrobacter sp. further oxidize the Nitrite Nitrogen (N/NO2) to Nitrate Nitrogen (N/NO3). Both of these are naturally occurring bacteria as a result of this Cycled Extended Aeration "CFCR" Process.
Nitrate, Nitrite, Ammonia and Organic Nitrogen are all inter-related in wastewater. All of these forms of Nitrogen, as well as Nitrogen Gas are biochemically interconvertible. Ammonia is generally found in large quantities in fresh domestic wastewater, however Nitrate is found only in small amounts. But in the effluent of conventional Nitrifying biological treatment plants, Nitrate is found in concentrations of up to 50 mg/L Nitrate Nitrogen. Nitrite is an intermediate state of Nitrogen, both in the oxidation of Ammonia to Nitrate and in the reduction of Nitrate to Nitrogen Gas. Such oxidation occurs in the I.D.E.A. System.
During non-aerated periods (sedimentation and decantation), the Dissolved Oxygen (DO) level in the sludge blanket (MLSS) approaches zero. The lack of molecular oxygen (O2) encourages Pseudomonas sp. and other denitrifying bacteria to attack the oxygen bound up in the Nitrate (NO3) molecules. The bacteria then reduce the Nitrate (NO3) molecules to nitrogen (N2) and oxygen (O2). The molecular Nitrogen (N2), a gas, is released to the atmosphere, while the bacteria utilize the liberated Oxygen (O2). Thus, alternation of oxic and anoxic periods in the I.D.E.A. basin promotes Ammonia Nitrogen (N/NH3) removal from the waste stream of 95% or better.
Additional Nitrogen removal is accomplished through assimilation (absorption and incorporation) of Nitrogen into bacterial cell mass in satisfaction of metabolic needs. This Nitrogen is removed from the system when excess sludge is wasted from the I.D.E.A. basin. Actual operating data have shown the concentration of nitrogen in the sludge mass to be between 5% and 8% by weight of the dry solids. As can be seen, the nutrient removals and high degree of treatment characteristic of tertiary treatment systems can be had at the cost of an I.D.E.A. "CFCR" secondary treatment system.
While the '860 application teaches the above improved apparatus and method it teaches primarily a circular IVE collector and a circular partition to surround the IVE collector which substantially limits the ratio of the bottom open area around the skirt to the volume ratio inside. The primary advantage of the present improvement is to make the IVE collector and the partition which surrounds it in the form of a rectangular configuration in order to increase the skirt ratio to the inside volume ratio thus causing hydraulic flow equalization velocity flow reduction.
In the past, other attempts have been made which address the problem of hydraulic velocity such as U.S. Pat. No. 4,468,327 which provides an elongated tank having a length between 3.5 and 6 times the width thereof which requires decanting from the opposite end of the tank from it's inlet and also teaches a transverse baffle across the tank dividing the tank into a first portion adjacent the inlet and a second portion remote from the inlet. The volume ratio of said first portion to said second portion being between about 1;10 to about 1;3. The baffle wall is not adjustable but has an opening at or adjacent to the lower edge of the baffle wall to allow influent passing into the tank to pass through the openings and into the main body of the tank. In the event of a "storm flow" situation, which occurs often especially when using lift stations as a means of influent input, all of the influent must pass through these openings and has been the source of excessive hydraulic flow which disturbs the sludge blanket in the main tank. The '327 reference has no means to change the ratio of hydraulic flow as does the present improvement and invention. Also the method claims of the '327 reference requires at least one transverse baffle and decanting at a point remote from the inlet.
Also, the prior art such as is illustrated by the '327 reference in what is commonly called the "pre-react zone" allows the incoming influent to create downward velocities in the pre-react chamber which does not allow undisturbed settling of the sludge blanket in that chamber during the air off settle and decant phases of their cycle.
Also, a ratio of no less than 1-10 is required in the pre-react zone. With this capacity of 10% to 30% of the total volume this system encounters extremely high flow velocities during hydraulic equalization between the pre-react and the main react zones during the settle and decant phases.
During times that the system is receiving peak influent flows and decanting, these transfer velocities will be as much as 6 times greater than those of the present invention.
The prior art also has no means to variably control the hydraulic velocities at start up when the sludge blanket is relatively thin as compared to the sludge blanket when it reaches maturity.
Also, the prior art such as is illustrated by the '327 reference does not have a naturally bio-mass filtering action in the first chamber but is relying on the transfer underneath the sludge blanket in the second chamber, thus requiring decanting at as remote a distance as possible away from the output of the first chamber so as to allow upset sludge caused by hydraulic flows to again settle before reaching the decanter at the other end of the tank. This again causes hydraulic disturbance and excessive overflow velocities as all the effluent must travel the full distance of the second chamber to reach the decanter means. Unlike the present invention, the prior art such as is illustrated by the '327 reference, requires an elongated tank to get the decanting process as far away as possible from the incoming influent and states that they require a length of 3.5 to 6 times the width.


A communications receiver for a code division multiple access (CDMA) satellite communication system in which a plurality of data carriers share the same band. A pilot carrier transmits a timing reference used by all receivers to acquire the clock used in timing the code generators, and used as a frequency and phase reference for data detection. This receiver employs a digital signal processor that detects a spread pilot carrier and uses the phase noise on the pilot carrier to subtract the communication link phase noise from the data carriers, thus allowing communication at lower signal-to-noise ratios.

The present invention relates to spread spectrum receivers and, more particularly, to a spread spectrum communication feed forward signal processor that uses a pilot carrier and a data carrier to reduce the effects of phase noise introduced by the transmission system.
Phase noise is a serious problem in commerical mobile satellite systems. Voice or data signals come from a telephone system into a fixed satellite terminal where they spread spectrum modulated onto a carrier and transmitted at Ku band to a satellite. The upconverter in this fixed station adds phase noise. The satellite receives the Ku band signal and translates it to L band. The translation is on the order of 10 GHz. In the vicinity of the mobile terminal the signal is scattered from trees and buildings, and the like, to add more phase noise due to mulitpath propagation. The mobile terminal receives the signal and translates it to baseband. All of these translations and the multipath propagation add phase noise. The total phase noise limits the system performance.
The phase noise problem is particularly severe where large frequency translations are used. In the above example, a 10 GHz carrier must be synthesized on the satellite to make the translation. This carrier is derived from a relatively low frequency crystal source (5 MHz). In the process of multiplying the frequency of the source, the phase noise of the source is also multiplied. The baseband to Ku band up-converter in the fixed uplink station also adds phase noise. However, higher purity sources are available for terrestrial application and the phase noise added to the link by the ground terminal is less than the phase noise added to the link by the satellite.
One problem with conventional spread spectrum communication receivers is that the phase noise of the pilot is added to the phase noise of the data signal, thereby degrading the performance.
In view of the disadvantages of conventional spread spectrum communication receivers, it was contemplated that a new and novel solution to the phase noise problem would process the signals in such a manner that the phase noise of the pilot would be substracted from the phase noise of the data signal, thus improving the performance. It was also contemplated that a novel solution to the phase noise problem would allow communication at lower signal-to-noise ratios on spread spectrum communication links corrupted by phase noise.

Feed forward spread spectrum signal processor


Methods and devices for analyzing posture-induced changes to physiological parameters of a patient (e.g., ejection time, heart rate, etc.) to provide an assessment of one or more conditions of the patient.

One or more conditions of a patient may be determined by analyzing physiological parameters of a patient such as heart rate, respiration rate, and blood pressure, etc. These physiological parameters may be different for a healthy individual versus one who is unhealthy or suffering from an affliction.
Further, such, physiological parameters may be affected by posture changes. For instance, a patient changing posture from a lying position to a more upright position may affect the patient's venous return due to gravity. As such, the patient's heart rate may increase to compensate for the hemodynamic effect due to gravity.
Hypervolemia, elevated tissue pressure, and increased venomotor tone in heart failure patients often tend to minimize the hemodynamic effects due to gravity. Such conditions may also be present in patients before dialysis. After dialysis, the physiologic effects of gravity on the patient's heart may be restored.

This patent is subject to a terminal disclaimer.

Posture-induced changes to physiological parameters


An optical scanning method is described in which a device essentially comprises a rotational optical system S and a working plane W fed in a predetermined direction. The optical system forms the image of a stationary point A at point B on the working plane W. The image point is scanned along a circular are by rotating the optical system around the rotational axis. In a preferred device, point A lies approximately on the rotational axis and point B lies off the rotational axis. And the circular arc generated by the scanning of point B is in the working plane approximately perpendicular to the rotational axis. A 2-dimensional scanning is completed by the rotation of the optical system around the rotational axis and the translation of the working plane in a predetermined direction, which is synchronized with the rotation of the optical system. When the radiation beam E propagates from point A to B, the device is for information writing in (e.g. lithography) and the working plane is a recording medium. When the radiation beam E propagates from the working plane to point A, the device is for information reading-out or pattern acquisition, in which a point detector is positioned right behind point A. This optical scanning method can be used in visible, UV, IR or soft x-ray waveband, providing, at the same time, large field of view, high resolution and very high data rate.

Optical-scanning techniques have found important applications in many areas, for example, laser printers for computers; laser direct writing lithography for production of masks, wafers and optical integrated circuits; high speed photography; IR imaging and image information transmission, graphic-art imaging for newspapers and other printed materials; and so on.
A summary of scanning methods is presented in the articles by Leo Beiser (Laser Focus/Electro-optics, Feb. 1985) and Henry E. R. Lassiter (Laser Focus World, Jan. 1991).
Optical-scanning by X-Y stage translation can only achieve low data rate because of the low translation speed of the stage. External or internal drum scanning may obtain medium data rate, but they can only be used for exposing winding materials. As a result, high resolution can not be achieved. Polygon scanning, in which the scanning trace is a straight line, can have high data rate, but the pixels per scanning line is less than 10.sup.5 or even less than 10.sup.4 since it is difficult to obtain an imaging optical system that has large angle of view as well as high resolution.
New developments of semiconducting devices are characterized by a continual decrease in the smallest dimensions and an increase in circuit size and complexity. In today's production environment, typical pixel dimensions range from 1 to 0.7 .mu.m. In laboratories, devices with structure sizes in the order of 0.5 .mu.m have been realized. In the 1990s, structures smaller than 0.5 .mu.m will be needed, e.g., for the production of 16 Mbit memory chips. The decrease in structural dimension not only permits a higher circuit complexity, but also an increase in speed and a decrease in power consumption, which is just as important.
The field of view of the objective in current projection lithographic stepper is smaller than 20 mm.times.20 mm. The linewidth d is determined by the wavelength used (.lambda.) and the quality of design and fabrication of the imaging system: ##EQU1## where K is about 0.5 to 0.9, determined by the quality of the image and NA is the numerical aperture of the objective which is normally smaller than 0.5. Because the depth of focus is inversely proportional to NA.sup.2, the optical system becomes difficult to use when NA is too large.
When a laser is used as the light source, the wavelength (.lambda.) may be shorter than 0.16 .mu.m. However, it is difficult to obtain an objective with a large field of view as well as a high resolution in extra UV wavelength due to the lack of appropriate optical material. C. W. T. Knight has recently reviewed some of these problems associated with future optical microlithography (Optics and Photonics News, Oct., 1990).
By using laser plasma, synchrotron x-ray sources or x-ray free electron laser, wavelength could be considerably shortened. Recently the development of soft x-ray multilayer coating has made soft x-ray projection lithography possible (D. L. White, et al., Solid State technology, July 1991, p37). In the past, soft x-ray was suggested for proximity lithography or projection lithography to improve system resolution and shrink structure sizes of integrated circuits. But, mask fabrication is very difficult and unstable. Moreover, soft x-ray projection systems can not achieve large area exposure. It is difficult to design a projection objective with large field of view and high resolution. Another problem is making a UV or soft x-ray optical system with a field of view larger than 20 mm and a pixel dimension smaller than 0.3 .mu.m, which is very important to the integrated circuit industry.
Recently laser raster scanning technique has been introduced for the production of masks and wafers with a resolution better than 1 .mu.m (M. Haruna et al, Applied Optics, 1987, v.26, p4587; C. Ransch et al, Applied Optics, 1989, v.28, p3754). As a direct writing lithographic method, it uses microscope objective with high resolution and small field of view, but writing speed is very slow.
Rotational scanning on planar surface on which the image spot is always focused has not become practical or useful for high speed and high resolution applications. A few rotational scanning devices are described in prior art patents: U.S. Pat. Nos. 3,588,218, 4,301,374, 3,704,372, 3,476,948, 4,413,180, 4,611,881. U.S. Pat. No. 3,746,948 discloses a room protection apparatus. U.S. Pat. No. 4,413,180 describes a robot vision system. Both devices are not imaging system and can not provide precise information of a surface during rotational scanning. U.S. Pat. No. 3,704,372 shows a rotary scan line/edge tracer using a motor driven mirror to produce the rotational scanning. There are a few problems for this device. The photocell detector is mounted adjacent the center of the stationary focusing lens which caused the loss of the light power and reduced the aperture of the lens. Furthermore, the stationary focusing lens after the rotational mirror greatly limits the field of scanning. The system can not be modified to be a recording system (e.g. for lithography) by replacing the photocell with a light source. U.S. Pat. Nos. 3,588,218, 4,301,374 and 4,611,881 describe rotational scanning devices for continuous scan in which one of the spots always scans the recording medium at any one instance. The scanner in U.S. Pat. No. 3,588,218 by Hunt et al uses an optical system with multi-focus spots which is sophisticated and technically difficult to build. To the skilled in the art, it is well known that the more complicated the optical system, the more stray light will be generated and the signal noise ratio will be decreased. Since all the spots, the image plane (the recording medium), and the planar mirror are in the same plane in the scanner, only flexible or soft recording medium can be used and because flexible recording medium such as a tape can not be made very planer, high resolution can not be achieved with such device. Moreover, because all spots are formed through different light paths which have different number of optical component, the brightness of each spot is different due to the sequential and inherent loss in light transmission and the quality of both recording and readout of data will be poor. Such difference in spot brightness will become especially significant when x-ray is used as the light source. Because the reflectivity of x-ray on the best mirror can be only about 60%, it can not be used as a light source in such devices. Schmidt (U.S. Pat. No. 4,611,881) discloses an optical apparatus for scanning radiation over a surface. A complex turnable structure with separated remote reflectors and central reflector is used. The central reflector needs to accelerate and decelerate repeatedly, which is impossible for high speed scanning required in the present art. Hashiue (U.S. Pat. No. 4,301,374) reveals an optical multi-lens scanner which is similar to some devices cited in that patent. For a four lens scanner, light source has to illuminate the entire active quarter of scanner and different part of light is allowed to pass a lens during scanning. As a result, most of the light power is wasted and this in turn greatly limits the speed of scanning because of the low exposure. The necessity of using a 50/50 mirror further impairs the light power. Moreover such illumination will cause stray light and decrease the image quality, even a shutter is used. In addition, in Hashiue's devices, the beam axis from the scanner to the detector system does not remain fixed during the scanning and the entrant direction of the light beam from the scanner to the detector changes with the rotation of the scanner. It is well known that the sensitivity of a detector is different for light coming from different direction and hence the performance of the detector in these devices will be greatly limited.

Optical scanning method with circular arc scanning traces


A method for forming an epitaxial layer involves depositing a buffer layer on a substrate by a first deposition process, followed by deposition of an epitaxial layer by a second deposition process. By using such a dual process, the first and second deposition processes can be optimized, with respect to performance, growth rate, and cost, for different materials of each layer. A semiconductor heterostructure prepared by a dual deposition process includes a buffer layer formed on a substrate by MOCVD, and an epitaxial layer formed on the buffer layer, the epitaxial layer deposited by hydride vapor-phase deposition.

1. Field of the Invention
The present invention relates to the growth of epitaxial films. The invention also relates to the growth of a buffer layer on a substrate and the growth of an epitaxial film on the buffer layer. The invention further relates to the epitaxial deposition of heterostructures by more than one growth technique. The invention still further relates to a two stage, or dual, process for growing gallium nitride and related materials epitaxial layers.
2. Background of the Related Art
Gallium nitride (GaN) and its related nitrides, including AlN, InN and alloys of these materials, are emerging as important technological material. For example, GaN is currently used in the manufacture of blue light emitting diodes, semiconductor lasers, and other opto-electronic devices. However, it is currently impossible to fabricate bulk GaN crystals of usable size as substrates in semiconductor manufacturing. Thus, GaN films are made by deposition on a non-native substrate material, typically sapphire (Al2O3). However, a large lattice mismatch and thermal mismatch exists between the Al2O3 substrate and the GaN layer. As a result, the material has large dislocation densities, which limit the performance of devices fabricated from these films, and at the same time restricts the applications for such GaN structures.
According to a prior art method for growing higher-quality GaN films, a relatively thick layer of an intermediate material can first be grown on the substrate as a buffer layer, and the GaN layer can then be grown on the buffer layer. Defects in GaN layers grown directly on sapphire substrates are due to major differences in inter-atomic spacing (lattice constant) and coefficient of thermal expansion (CTE) between the substrate and GaN. Therefore, if the buffer layer has a lattice constant and CTE closer to those of GaN, the GaN (top) layer will have fewer defects, and will be of higher quality. High quality GaN layers are necessary for electronic and opto-electronic devices. A material which meets the desired lattice constant and CTE criteria is aluminum nitride (AlN).
Prior art methods of fabricating heterostructures, having a GaN layer on a buffer layer, have used the same growth technique for both layers. For example, both semiconductors (the AlN buffer layer and the GaN layer) can be grown by metal-organic chemical vapor deposition (MOCVD). In this technique, ammonia gas (NH3) is reacted with a metallo-organic compound containing aluminum or gallium, such as trimethyl aluminum (TMA), triethyl aluminum (TEA), trimethyl gallium (TMG), or triethyl gallium (TEG). The reaction occurs at high temperatures in the vicinity of a substrate, and a solid product (GaN or AlN) is deposited on the substrate. However, this technique is not only expensive, but also slow. In particular, the metallo-organic source materials are costly, and they can only be delivered to the substrate for reaction at low rates.
A currently favored prior art technique for the growth of relatively thick layers, e.g., of GaN, is HVPE. In this process, growth proceeds due to the high-temperature vapor-phase reaction between gallium mono-chloride (GaCl) and ammonia. The ammonia is supplied from a standard gas source, while the GaCl is produced by passing hydrogen chloride (HCl) gas over a liquid gallium (Ga) supply. Using this method, GaN can be grown relatively quickly and inexpensively. Further, GaN grown at a fast rate may produce layers with less defect densities.
However, due to difficulties involved in providing a supply of aluminum chloride (AlCl), HVPE cannot be used for the efficient growth of an AlN buffer layer. (For example, when HCl is passed over Al metal, the AlCl that is formed immediately solidifies, and is not carried towards the substrate.) Consequently, AlN layers must be grown by techniques other than HVPE, such as MOCVD.
The above delineated disadvantages associated with prior art methods for deposition of AlN/GaN heterostructures are addressed by the present invention, in which a buffer layer (e.g., AlN) and an epitaxial layer (e.g., GaN) are grown using different techniques, as will be described fully hereinbelow.
In view of the above, it is an object of the present invention to provide a semiconductor heterostructure and method of making the same.
One feature of the invention is that it provides a two-stage process for fabricating a semiconductor heterostructure.
Another feature of the invention is that it provides a semiconductor heterostructure prepared by growing an epitaxial nitride layer on a buffer layer, the buffer layer deposited by a technique other than HVPE.
Another feature of the invention is that it provides a method of growing a semiconductor heterostructure, wherein a buffer layer is first grown on a substrate by metallo-organic chemical vapor deposition, and an epitaxial layer is subsequently grown on the buffer layer by hydride vapor-phase epitaxy.
Another feature of the invention is that it provides an epitaxial nitride layer formed on a substrate formed by MOCVD.
One advantage of the invention is that it provides a method for fabricating a semiconductor heterostructure by two different deposition processes, wherein each process is optimized for the material to be deposited.
Another advantage of the invention is that it provides an epitaxial layer formed by HVPE on a buffer layer formed by MOCVD.
Another advantage of the invention is that it provides an efficient method for forming an epitaxial nitride layer suitable for electronic and opto-electronic devices.
These and other objects, advantages and features are accomplished by the provision of a method of making a semiconductor heterostructure, including the steps of: a) providing a substrate; b) forming a buffer layer on the substrate to form a buffer-layered substrate; c) forming a cap layer on the buffer layer; and d) forming an epitaxial layer on the cap layer, wherein the buffer layer is formed by MOCVD, MBE or other suitable CVD techniques, and the epitaxial layer is formed by HVPE or other suitable techniques.
These and other objects, advantages and features are accomplished by the provision of a semiconductor heterostructure, including: a buffer layer, said buffer layer formed by MOCVD; and an epitaxial layer disposed on said buffer layer, said epitaxial layer formed by HVPE.
These and other objects, advantages and features are accomplished by the provision of an epitaxial layer prepared according to a method including the following steps: a) forming a buffer layer on a substrate by MOCVD , MBE, sputtering or other suitable CVD techniques; b) forming a cap layer on the buffer layer; and c) forming an epitaxial layer on the cap layer by hydride vapor-phase epitaxy.
These and other objects, advantages and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The advantages of the invention may be realized and attained as particularly pointed out in the appended claims.

Dual process semiconductor heterostructures and methods


A trenching apparatus having a digger arm operative to form a trench along a trench line includes a lower end which mounts a digging and propulsion unit having an upper and lower group of sprockets which are vertically spaced from one another and carry chains having digger teeth mounted thereto. Structure is provided to increase the relative spacing between the upper and lower sprockets, while the chains remain in engagement therewith to increase tension in the chains as they wear and a number of scraper blades are mounted in position relative to the sprockets and the shafts which carry them to prevent the buildup of soil, concrete, rocks or other foreign material thereon and thus ensure smooth operation of the digging and propulsion unit.

The erection of above-ground structures, particularly in relatively sandy soil, often requires the formation of in-ground retaining walls for use as a load-bearing foundation or as a barrier to prevent the collapse of soil into the excavated area. Where such excavations are made adjacent an existing structure, the retaining wall along the excavation line adjacent the existing structure is necessary to resist soil pressures established beneath the adjoining structure. If no retaining wall is formed, the soil beneath the adjoining structure can collapse outwardly into the excavation site and/or damage the existing structure. In addition to retention of soil, retaining walls of this type are often constructed to block the flow of ground water into the excavated area.
A number of methods have been used to form retaining walls around an excavation site where adjacent structures adjoin such a site. One method has been to employ piles formed of wood or steel which are driven along the excavation line to form the retaining wall. Alternatively, a row of bored holes are formed along the excavation line which receive reinforced concrete piles to form the retaining wall. Both of these methods produce retaining walls which are not water-tight and which may require substantial horizontal strengthening to maintain the desired alignment along the excavation line.
Trenching apparatus such as disclosed in U.S. Pat. No. 4,843,742 to Camilleri have been proposed as an alternative to the methods and apparatus of forming retaining walls mentioned above. In trenching apparatus of this type, a supporting base capable of being moved in a longitudinal direction along a trench line carries an elongated digger arm supported on one side thereof by a boom structure. The support base is drivingly connected to skids or track assemblies of the type employed in conventional bulldozers or other excavation equipment which are effective to move the support base and digger arm along the trench line to form a trench of the desired depth. Concrete is poured into the trench in which appropriate reinforcement bars have been inserted immediately behind the moving trenching apparatus. In this manner, an essentially continuously formed, reinforced concrete retaining wall is provided a the excavation site.
Located at the lower end of the digger arm of the trenching apparatus disclosed in the 4,843,742 Camilleri patent is a digging and propulsion unit. This unit is initially placed atop the ground along the trench line and is operated to dig downwardly with the digger arm into the soil to the desired depth of the trench. As the boom structure mounted to the support base moves the upper end of the digger arm along the trench line, the digging and propulsion unit located below ground propels the lower end of the digger arm within the trench by operation of digger teeth carried by drive chains.
One problem with the digging and propulsion units of the type described in U.S. Pat. No. 4,843,742 is the loss of tension in the chains thereof as a result of wear. As the chains loosen, they do not effectively propel the lower end of the digging arm. To restore the proper tension to the chains associated with the digging and propulsion unit, the digger arm must be withdrawn from the trench, the worn chain(s) removed, and new chains installed. Such a procedure is inefficient an time-consuming.
A second problem with digging and propulsion units of the type disclosed in U.S. Pat. No. 4,843,742 is the accumulation of digging debris on the sprockets and shafts within the digging and propulsion unit which carry and drive the chains. Dirt, clay, concrete, sand, rocks and other materials tend to adhere to the hubs of the sprockets within the digging and propulsion unit and interfere with the travel of the digging chain about the sprocket and/or rotation of the sprocket. Periodically, the digger arm must be lifted out of the trench and workmen must use implements to remove the debris from the sprockets, shafts and chains. This procedure is labor intensive, time-consuming and adds expense to the cost of erecting the retaining wall.
A third problem with digging and propulsion units of the type disclosed in U.S. Pat. No. 4,843,742 is the rapid wear of the teeth or tips mounted to the chain(s) which dig downwardly to the initial trench depth, and then propel the lower end of the digging arm. Particularly in rocky or compacted soil, such as clay, these tips tend to wear after a short period of time requiring replacement of the individual tips or the entire chain.

Digging and propulsion unit for a trenching apparatus


A process for creating an array of bumps to texture a brittle nonmetallic surface, such as a glass substrate for data recording disks. The texturing process uses a laser to provide pulses of proper energy fluence to the brittle glass surface to produce a plurality of raised bumps in the surface. The bump creation is accomplished without unwanted micro-cracking or ejection of surface material by limiting the laser pulse fluence to a value in a narrow operating region discovered below the abrupt thermal shock fluence threshold for the brittle nonmetallic surface material. The process is also applicable to other brittle surface textures, such as those intended for use as "stamping surfaces" for the contact reproduction of the negative of a surface pattern, such as an optical disk.

1. Field of the Invention
This invention relates generally to processes for texturing data storage disk substrates and specifically to a highly controllable laser texturing process for brittle nonmetallic surfaces such as a glass substrate for a data storage disk.
2. Description of the Related Art
Recent magnetic disk drive designs employ a commonly denominated Contact Start-Stop (CSS) system in which the magnetic head contacts the magnetic disk surface when the disk is stationary. When the disk starts to rotate, the magnetic head slides along the surface, eventually flying fully lifted from the surface because of laminar air flow at the disk surface.
A smooth, specular recording surface is preferred in the art to permit the magnetic head to ride as closely as possible to the disk surface. Creation of a "textured" region on the metallic disk surface for magnetic head contact during CSS is used in the art to overcome the excessive contact stiction and friction developed during startup and stopping of disk rotation. The magnetic head is moved to the "CSS region" at the appropriate times by the drive controller. The specular smoothness of the remainder of the disk surface is retained to permit high-density magnetic data recording.
Practitioners in the art have proposed several useful techniques for texturing metal disk surfaces. For instance, the use of repetitive laser pulses to create reproducible pits on a metal surface is known in the art for application to sheet-metal stamping surfaces, liquid transfer surfaces and metal data storage disk surfaces, as discussed in the above-cited co-pending patent application. Unfortunately, such techniques are not generally useful for texturing of brittle nonmetallic disk substrate surfaces such as the glass substrate known in the art for certain data storage disk applications. A brittle nonmetallic surface, especially a glass surface, is expected to crack or deform excessively during the grinding or laser texturing techniques known in the art for metal disk substrates. Accordingly, chemical surface texturing techniques and other patterned deposition techniques are preferred in the art for brittle surfaces such as ferrite or glass.
For instance, in U.S. Pat. Nos. 5,079,657 and 5,162,073, Michael I. Aronoff et al. disclose a selective chemical etching technique for texturing the flying surface of a magnetic head. Aronoff et al. teach a stiction-reducing approach that avoids the necessity of texturing a CSS region on the recording disk but is disadvantageously limited to specific head surface materials.
In U.S. Pat. No. 4,985,301, Toshinori Morizane et al. disclose a method for manufacturing a glass base plate for a recording disk that includes subjecting the base plate to chemical etching treatments that provide different rates of etching between a crystallized material and an amorphous material. Morizane et al. teach the use of their method for creating a textured CSS region in the base plate that is reproduced through a subsequently-deposited recording material layer. Other practitioners have suggested using expensive chemical vapor deposition (CVD) processes to create roughened zones on a glass disk surface before deposition of the magnetic recording film layer.
Some practitioners in the printing arts teach the use of laser pulses to create many tiny pits in the surface of a brittle material such as tungsten carbide. For instance, in U.S. Pat. Nos. 5,143,578 and 5,236,763, Pierre Luthi discloses a method for engraving a series of consecutive cells or pits in a solid surface such as the liquid transfer surface of a priming roller. Luthi recommends his technique to overcome the surface hardness of the ceramic and metal carbide surfaces normally used in engraving applications but neither considers nor suggests solutions to the particular problems of CSS region creation in brittle nonmetallic disk surfaces to overcome head stiction.
Others have considered the specific problem of using laser energy for reducing stiction in data recording disks having glass substrates. For instance, in Japanese patent 4-311814, Maeta Hiroshi discloses a technique for texturing the glass substrate without reducing surface durability by applying a laser pulse from the back of the translucent substrate to fracture and scatter small particles of glass at the front surface. The laser pulse induces thermal shock that effectively breaks up the front surface into fine grains that are then supposedly partially annealed to the front surface, creating a roughened topography suitable for reducing stiction in the magnetic recording film layer that is later added to the front glass substrate surface. Hiroshi doesn't discuss how his method overcomes the problems resulting from uncontrolled surface damage.
In U.S. Pat. Nos. 5,062,021 and 5,108,781, Rajiv Ranjan et al. disclose a process for creating a series of closely-spaced pits in the metallic surface of a magnetic recording disk to reduce stiction. Ranjan et al. teach the use of a flashlamp-pumped neodymium-yttrium-aluminum-garnet (Nd:YAG) laser to create the necessary surface roughness. However, they neither consider nor suggest the application of their texturing method to glass disk substrates or other brittle nonmetallic surfaces, and indeed their method is generally known to be impractical for brittle nonmetallic materials.
Practitioners in the art generally avoid using laser pulses to create controlled changes to the topography of a brittle nonmetallic surface, expecting hair-line cracking or surface material damage. This damage, often at the microscopic level, is frequently observed after laser melting of any brittle nonmetallic material such as glass because of the rapid melting and resolidification caused by a short laser pulse. This rapid melting and resolidification usually causes excessive stress in the glass, which forces the surface to crack and break up. Such laser pulses are herein said to create stress that exceeds a "thermal shock threshold" for the brittle nonmetallic surface material. Indeed, the above-cited Hiroshi patent relies on this thermal shock micro-fracturing phenomenon for the usefulness of the claimed invention. Laser pulse energies below this threshold are generally believed to be useless for altering the topography of brittle nonmetallic surfaces.
Accordingly, there is a clearly-felt need in the art for a brittle nonmetallic surface texturing technique with the controllability and other advantages of the laser-texturing techniques known in the art for metal surfaces. The related unresolved problems and deficiencies are clearly felt in the art and are solved by this invention in the manner described below.

Process for texturing brittle glass disks

International Business Machines Corporation


The invention concerns a method of signaling an internal status of an implantable cardiac stimulation device, which status is defined by a value of a status parameter, including the steps: a) Recording a measurement value (S12) representing the status parameter, b) Ascertaining the existence of the status by comparison of the measurement value with a comparative value (S14), c) Delivering a signal pulse with a predetermined, measurable pulse parameter, wherein the pulse parameter is uniquely associated with the status if the measurement value corresponds to the comparative value within predetermined limits (S26). In accordance with the invention the time difference of equal, predetermined phases of two successive, periodically recurring events prior to delivery of the signal pulse is measured (S20), and then the signal pulse is delivered prior to or after the next expiry of the measured time difference by a predeterminable period of time uniquely associated with the status (S22, S24, S26). The invention further concerns a cardiac stimulation device for carrying out that method.

The invention concerns a method of signaling an internal status of an implantable cardiac stimulation device, which status is defined by a value of a status parameter, as set forth in the classifying portion of claim 1. The invention further concerns a cardiac stimulation device as set forth in the classifying portion of claim 10.
Methods and apparatuses for external recognition of the technical status of an implantable cardiac stimulation device are known, which make it possible to take the desired information about the technical status from the stimulation pulses which are delivered by the device. In particular, U.S. Pat. No. 5,899,928 discloses a signaling method in which the item of information to be communicated is encoded as a defined period of time between two successive stimulation pulses. After a measurement value representing a status parameter has been recorded, it is associated by comparison with one of three comparative value intervals. Associated with each of those comparative intervals is a defined pulse spacing in respect of time, of 500, 600 or 700 ms. Delivery of signal pulses of that kind is effected after detection of an external magnetic field. In order to clearly identify a subsequent pulse or a subsequent pulse sequence as signaling pulses, a xe2x80x9csynchronization pulsexe2x80x9d which is not described in greater detail is previously produced. A disadvantage with that method is that it can only be used when the natural cardiac rhythm is totally nullified by the use of pacemaker therapy. A method of that kind cannot therefore be used in relation to a xe2x80x9cdemandxe2x80x9d pacemaker or cardioverter/defibrillator because in that case stimulation pulses are delivered only in situations in which the status of the heart, which is monitored by a measurement procedure, requires that.
The object of the present invention is to provide a method and a cardiac stimulation device of the kind set forth in the opening part of this specification, which do not suffer from the stated disadvantages.
In terms of a method of the kind set forth in the opening part of this specification, that object is attained by a method of signaling an internal status of an implantable cardiac stimulation device, which status is defined by a value of a status parameter, including the following steps:
a) recording a measurement value representing the status parameter,
b) ascertaining the existence of the status by comparison of the measurement value with a comparative value,
c) measuring the time difference of equal, predetermined phases of two successive, periodically recurring sequences of events, and
d) delivering at least one signal pulse with a predetermined, measurable pulse parameter, if the measurement value corresponds to the comparative value within predetermined limits, wherein the pulse parameter is uniquely associated with the status by the delivery of the signal pulse being effected prior to the next expiry of the measured time difference by a predeterminable period of time uniquely associated with the status.
The method according to the invention provides that the moment in time of delivery of the signal pulse is coupled to a predetermined phase of a periodically recurring sequence of events. The term sequence of events is used to denote a number of events which occur in succession in respect of time. A phase of that sequence of events is defined by a given one of those events. The moment in time at which the phase occurs is the moment in time at which that given event occurs. The spacing in respect of time between the individual events of the sequence of events can vary from one period to another so that the duration of the sequence of events, that is to say of a period, can also be variable each and every time. This is an essential advantage of the method according to the invention: there is no need for coupling of the moment in time of delivery of the signal pulse, to a predetermined period duration. Implementation of the method according to the invention is not bound to predetermined boundary conditions in regard to period duration and can thus be used in a more variable fashion.
The current period duration is measured in the course of implementation of the method with step c) only shortly before delivery of the signal pulse. For that purpose, the time difference of two predetermined, identical phases of successive periods is determined. The later one of those two phases is within the last, completely passed period, prior to delivery of the signal pulse. Determining the moment in time of delivery of the signal pulse relative to the periodic sequence of events is based on the measured moment in time of the last occurrence of the predetermined phase, the measured period duration and the predetermined time displacement.
The predetermined, measurable pulse parameter which serves for signaling purposes is a time displacement in respect of delivery of the signal pulse with respect to the occurrence of the given phase of the periodic sequence of events.
The method is preferably used in relation to an implantable cardiac stimulation device. However, implantation of the device in the human body is neither a partial step in nor a necessary prerequisite for executing the method according to the invention. The method can equally be used in relation to a non-implanted cardiac stimulation device, for example for test purposes in the context of quality control immediately after manufacture or immediately prior to an implantation procedure.
The periodically recurring sequence of events can be internal or external in relation to the implantable cardiac stimulation device. Delivery of the signal pulse can for example be coupled to a periodic clock signal which is an internal signal, that is to say which is produced in the cardiac stimulation device, and the frequency of which is pre-settable, that is to say independent of the duration of a cardiac period. That frequency can also be variable.
In preferred embodiments of the invention the signal pulse is delivered in time relationship with a periodically recurring sequence of events which is external, that is to say which is produced outside the cardiac stimulation device. This involves for example an external ultrasonic pulse which is detected by means of an ultrasonic sensor integrated in the cardiac stimulation device. The ultrasonic sensor produces a pulsed electrical signal corresponding to the ultrasonic pulse. The time difference of equal, predetermined phases of two successive pulses of that electrical signal is measured and used for control in respect of time of the subsequent delivery of the signal pulse.
In a particularly preferred embodiment of the invention the periodically recurring sequence of events is coupled to cardiac activity. The sequence of events can be for example the occurrence of a defined phase of a measurement signal which reflects the time pattern or variation in cardiac activity. In this respect, it is already sufficient if that measurement signal only reflects the onset of a given phase of cardiac activity. In this connection, c) of the method of the invention involves measurement of the time difference of equal, predetermined phases of two successive cardiac periods prior to delivery of the signal pulse. In terms of the implementability of the method according to the invention, it is immaterial whether the cardiac activity is stimulated or natural.
Measurement of the time difference of equal, predetermined phases of two successive cardiac periods is effected here solely to determine the moment in time of the subsequent delivery of the signal pulse, in accordance with step d) of the method. The measurement data obtained are not used to produce a medical diagnosis in respect of cardiac activity, but serve solely for technical purposes.
It will be appreciated however that the measurement data obtained with step c) of the method can be used for diagnostic measures. Such diagnostic measures however are not related to the claimed method which is concerned solely with signaling an internal technical status of a cardiac stimulation device. Such an internal status is defined for example by a value of the output voltage of an accumulator, or the electrical resistance of an electrical conductor between components of the cardiac stimulation device.
It will be appreciated that surgical, diagnostic or therapeutic measures which lie outside the claimed method can open up further profitable possible uses of the method according to the invention. For example the signaling method according to the invention can be used in a cardiac stimulation device in order to signal cardiac arrhythmia phenomena such as tachycardia which are detected by a diagnostic process which is not subject-matter of this application, in response to an external inquiry.
Known therapeutic measures also open up areas of use to the signaling method according to the invention. For example the method according to the invention can be used in a cardiac stimulation device which is designed to implement xe2x80x9con-demandxe2x80x9d pacemaker therapy. Depending on whether pacemaker therapy is or is not implemented at the moment in time of signaling, two situations are possible. In one situation the signal pulse is delivered subsequently to cardiac stimulation pulses which are produced in the course of the pacemaker therapy. In the other possible situation delivery of the signal pulse occurs in a period of time in which the heart beats independently without the application of therapy. In both situations delivery of the signal pulse is outside the therapeutic measures. It is here that an essential advantage of the method according to the invention manifest itself: it operates independently of whether cardiac activity is stimulated or natural.
The signal pulses can be delivered to the cardiac muscle in the form of electrical current pulses by way of a stimulation electrode of the cardiac stimulation device. The signal pulses can be uniquely distinguished from the cardiac stimulation pulses delivered in the context of pacemaker therapy, by virtue of the moment in time at which the pulses are delivered. That moment in time is determined in accordance with steps c) and d) of the method according to the invention.
A preferred embodiment of the method according to the invention is started as soon as a triggering signal is present in the cardiac stimulation device. As long as the triggering signal is not present, the method is not started. Production of the triggering signal is preferably coupled to an external event or an external status change. For example, the triggering signal can be produced if a magnetic field or an ultrasonic signal involving predetermined parameters are detected at the location of the cardiac stimulation device. Such an event can indicate for example the reception readiness of a receiver for the signal pulse.
If the triggering pulse is still present after the signaling method has been carried into effect, the signaling method in a further embodiment is carried into effect again. In that way, correct reception of the signal pulse can be checked on the part of the receiver. Particularly besides a pacemaker therapy process, repeated implementation of the method promotes certainty of the correct interpretation of the signal pulse. For, signaling of the internal status of the cardiac stimulation device can be detected by virtue of the time displacement of the signal pulse in comparison with the time spacing of two immediately preceding cardiac stimulation pulses. A slight time displacement however can be difficult to resolve in terms of measurement procedures and can be such that it can only be uniquely identified after repeated delivery of the signal pulse.
A further embodiment of the method according to the invention is distinguished in that, subsequently to delivery of the signal pulse, for a predeterminable number of subsequent sequences of events, no signal pulse is produced. If the triggering signal is present over a relatively long period of time, that results in a periodically repeated series of events which includes the predetermined number of periodic events and a subsequent signal pulse. That series of events is repeated as long as the triggering signal is present. The benefit of that embodiment is that the signal pulse can be more easily recognized by virtue of its repetition after a regular, predetermined number of events.
Typically, the predetermined number of events between the signal pulses is five. Preferably, the invention provides for external programmability of that number so that for example it can be variably preset between two and twelve.
In a further embodiment of the signaling method according to the invention a physical parameter which is dependent on the phase in the cardiac cycle is measured. Preferably, an electrocardiogram is recorded. Recording of the electrocardiogram can be effected by means of separate electrodes or, in the case of implanted cardiac stimulation unit, by means of the stimulation electrodes. The time difference of equal phases of two successive cardiac periods can be measured in known manner by reference to an electrocardiogram. In this embodimentxe2x80x94as was discussed in detail hereinbeforexe2x80x94recording of the electrocardiogram does not serve for any diagnostic purposes whatsoever, but only for near-time pre-determination of the moment in time for delivery of the signal pulse, corresponding to step d) of the method according to the invention.
At the present time use of the method according to the invention is preferred in an embodiment in which the measurement value which is to be recorded and which represents the status parameter is an electrical voltage which occurs at the output of an energy storage means arranged in the cardiac stimulation device. The output voltage of the energy storage means is recorded as a measurement in respect of its energy content. If in the passage of time the output voltage falls to or below a predetermined comparative value, a signal pulse is generated when the triggering signal is present. In that way, the presence of internally registered statuses of the energy storage means such as xe2x80x9cEOLxe2x80x9d (end-of-life) or xe2x80x9cERIxe2x80x9d (elective-replacement-indication) becomes accessible to external recognition which can be easily implemented, for example in the course of a routine check in the practice of a general practitioner. Referral to a specialist is only required when the presence of one of those statuses has actually been signaled.
In regard to a cardiac stimulation device, the object of the invention is attained by a cardiac stimulation device comprising a pulse generator which is adapted to produce pulses suitable for cardiac stimulation, at least one stimulation electrode connected to the pulse generator and adapted to deliver the pulses, a signal generator connected to the pulse generator and adapted to produce and delivery pulse triggering signals at defined moments in time, a cardiac phase measurement sensor adapted to record a first measurement value dependent on the current phase of the cardiac cycle, time measurement means connected to the cardiac phase measurement sensor and adapted to determine a cycle duration between the occurrence of a predetermined phase of a defined first cardiac cycle and the occurrence of the same phase of the immediately successive, second cardiac cycle, and time matching means which are connected to the time measurement means and on the output side to the signal generator and which are adapted to predetermine the period of time between the occurrence of the predetermined phase of the second cardiac cycle and the subsequent production of a pulse triggering signal.
The cardiac stimulation device according to the invention has time matching means. They receive from the time measurement means a cycle duration signal which corresponds to the duration of the cardiac period which last elapsed.
In this respect, the term duration of a cardiac period is used to denote the time difference between the occurrence of a given phase in a cardiac cycle and the occurrence of the same phase in the immediately subsequent cardiac cycle. The operation of determining the spacing in respect of time between identical phases of successive cardiac periods is carried into effect for example on the basis of the occurrence of R-spikes. The simplest thing however is to measure the time interval between the Q-spikes. Measurement of the period duration is started and stopped with the attainment of a predetermined voltage threshold value which in the present embodiment is negative. That time measurement method operates reliably both in relation to natural and also to stimulated cardiac activity.
On the basis of the cycle duration signal, the time matching means predetermines the period of time which will elapse from the end of the measured cardiac period, that is to say from the last occurrence of the given phase, to the subsequent production of a pulse triggering signal.
The cardiac stimulation device according to the invention, by virtue of the time matching means, is capable of predetermining the moment in time of subsequent production of a signal pulse after a stimulated and in particular also after a natural, non-stimulated cardiac activity. The question of whether the cardiac period whose duration was determined by virtue of the time measurement means came about due to a stimulated or a non-stimulated, natural cardiac activity, is immaterial in regard to subsequent signaling.
In the case of the device according to the invention a signal pulse is a pulse which is suitable for cardiac stimulation. Preferably the signal pulse is in the form of a ventricular stimulation pulse. The signal pulse is the same in terms of its pulse parameters such as voltage and duration as the cardiac stimulation pulses which are usual in the context of pacemaker therapy, apart from the moment in time at which it is delivered. The signal pulse differs from stimulation pulses by virtue of its displacement in respect of time relatively to the current phase position of the cardiac activity.
The moment in time at which a signal pulse is produced is predetermined in the case of the cardiac stimulation device according to the invention only shortly before it is triggered off. Directly after the cardiac period which last elapsed, the duration thereof having been determined by the time measurement means for example on the basis of the QQ-time interval, the moment in time of delivery of the signal pulse is calculated by means of the time matching means.
The period of time between the end of the last cardiac period, for example the last Q-spike, and the moment in time of delivery of the signal pulse, which is predetermined by the time matching means, differs from the measured period duration by a significant, measurable time difference. In that way, it is possible to produce a signal pulse which is matched in respect of its delivery time to the instantaneous cardiac period duration, and in that respect therefore it is xe2x80x9csynchronizedxe2x80x9d. For it is to be assumed that the cardiac period duration changes only insignificantly from one period to the next.
The device according to the invention is therefore not reliant on a fixed stimulation rhythm, with a departure therefrom for the signaling procedure. On the contrary, it is adapted by way of the time matching means in the production of a signal pulse to the instantaneous and possibly natural cardiac rhythm. That is a matter of great significance in particular in relation to defibrillator patients as they could react to asynchronous production of cardiac stimulation pulses, with a cardiac arrhythmia. The quasi-synchronous production of a cardiac stimulation pulse which serves for signaling purposes, by means of the device according to the invention, avoids that risk.
In the case of the cardiac stimulation device according to the invention the time matching means are adapted to cause the delivery of a signal pulse, that is to say a time-displaced cardiac stimulation pulse, immediately after measurement of the duration of a cardiac period. In regard to the choice of the time displacement, on the one hand account is to be taken of the fact that the time displacement can be externally detected. Therefore the time displacement should be sufficiently great that doctors or medical personnel can identify a time-displaced stimulation pulse by way of evaluation of an ECG, more specifically both in relation to otherwise natural cardiac activity and also in relation to stimulated cardiac activity. On the other hand, the time displacement of the signal pulse is to be so selected that the risk of triggering off a cardiac arrhythmia by the signal pulse, if not completely avoided, is nonetheless kept down at a particularly low level. Making it possible to provide for matching in respect of time of the signal pulse in relation to the current phase position of the cardiac activity, whether stimulated or non-stimulated, in order to avoid stimulation in a vulnerable phase, is a major advantage of the invention. The signal pulses are preferably delivered in the form of premature ventricular stimulation pulses.
The time matching means provide for delivery of the signal pulse, which is phase-matched in relation to the cardiac period. For that purpose, they access the measurement values in respect of the period duration, which are produced by the time measurement means. As the time measurement means measure the period duration on the basis of the occurrence of a given phase of cardiac activity, the phase position of the cardiac activity is also determined, with the phase duration. The time matching means use both items of information for careful gentle delivery of signal pulses.
Signal pulse delivery, which is not pro-arrhythmic, is ensured if the moment in time of delivery of the signal pulse avoids the vulnerable phase of the ventricular cardiac cycle. The vulnerable phase of the cardiac chambers approximately coincides with the rising edge of the T-wave of the ECG.
Hereinafter the details relating to the time displacement of the signal pulse are based on the moment in time, as determined by the time measurement means, of the last occurrence of the Q-spike. It will be appreciated however that the value of the time displacement would be different if measurement of the cardiac period duration were based on another phase in cardiac activity. What is important is the phase position, as determined by such details, of the moment in time of delivery of the signal pulse relative to the cardiac period.
In an embodiment, the time matching means are adapted to produce the pulse triggering signal which results in the production of the signal pulse by the pulse generator, no earlier than 300 ms prior to the expiry of the given cycle duration after the occurrence of the predetermined phase of the second cardiac cycle. That time displacement in relation to the current cardiac rhythm can be easily recognized in the surface ECG.
In a particularly preferred embodiment the premature cardiac stimulation pulse is produced no earlier than 200 ms prior to the expiry of the given cycle duration after the occurrence of the predetermined phase of the second cardiac cycle. Stimulation pulses which are delivered prematurely by between about 100 and 200 ms can also be easily detected in the surface ECG. In order to ensure detectability on the surface ECG, a premature cardiac stimulation pulse should be produced no later than 50 ms prior to the expiry of the given cycle duration after the occurrence of the predetermined phase of the second cardiac cycle.
A further embodiment of the apparatus according to the invention has a status measurement sensor which is connected to the time matching means and which is adapted to record at least one status measurement value which depends on the current value of a status parameter of the device. It is particularly borne in mind that the status measurement sensor is so adapted that the status measurement value depends on the energy content of an energy storage means of the device. However, other measurable status parameters can also be detected by a suitably designed status measurement sensor, for example the electrical resistance of stimulation electrodes connected to the device. Diagnostically ascertained states of the heart of the patient or given pathological events such as for example cardiac arrhythmia can also be detected by a status measurement sensor and signaled to the exterior by the cardiac stimulation device.
An embodiment includes a comparative value storage means for recording at least one comparative value for the status measurement value. In that case, monitoring of the status measurement value is preferably effected by first comparison means which are connected on the input side to the status measurement sensor and the comparative value storage means and on the output side to the time matching means. The comparison means are adapted to compare the status measurement value to the comparative value and to produce and deliver a status signal which is dependent on the comparison result.
If the status signal indicates that the status measurement value does not coincide with the comparative value within predetermined limits, the time matching means are activated. In an embodiment of the invention, activation of the time matching means is effected by means of a monitoring unit which is connected on the input side to the first comparison means and on the output side to the time matching means. The monitoring unit compares the status signal to at least one pre-stored reference status value range and produces a waiting signal if the status signal is not contained in the reference status value range. The waiting signal is transmitted to the time matching means.
In order to avoid the production of unnecessary signal pulses in situations in which no external receiver is ready to record the signal pulse, a further embodiment of the invention has an activation measurement sensor which is connected to the time matching means. The activation measurement sensor serves to receive measurement values (hereinafter referred to activation measurement values) of an activation measurement parameter. That can be for example a magnetic field strength as is produced by currently available external pacemaker testing units. It is only when the activation measurement sensor detects a magnetic field of predetermined field strength that in this embodiment the time matching means are activated.
Evaluation of the measurement values recorded by the activation measurement sensor, in a further embodiment, is effected by means of second comparison means which are connected at the output side to the monitoring unit. The second comparison means access a pattern value storage means. Pattern activation values can be stored in the pattern value storage means. These involve activation measurement values with given parameters to which is attributed the significance of reception readiness of an external receiver for the signal pulse. The second comparison means compare the current activation measurement value to the pattern activation value contained in the pattern value storage means. In the event of the activation measurement value coinciding with the pattern activation value, the comparison means produce a triggering signal which is received by the monitoring unit.
In this embodiment, the monitoring unit produces a waiting signal only when the status measurement value is outside its normal value range and at the same time the activation measurement value indicates that the signal pulse to be produced can be detected by an external receiver.
In an embodiment, the cardiac phase measurement sensor is adapted to pick up a measurement signal which is dependent on the electrical polarization of the myocardium, preferably to record an electrocardiogram. The cardiac phase measurement sensor can be provided specifically, that is to say for example in the form of one or more implanted derivation electrodes. Where possible however the stimulation electrodes are preferably at the same time in the form of cardiac phase measurement sensors and can therefore be used both to stimulate the heart and also to record an ECG.
A regular sequence of normal and time-displaced events facilitates identification of the signal pulse which is delivered by the stimulation device, in terms of evaluation of a surface ECG. In an embodiment which is designed for that purpose the device according to the invention has pacemaker control means which are connected to the time matching means and which are adapted for the selective production of an activation or a deactivation signal for respectively activating or deactivating operation of the time matching means. The pacemaker control means are preferably connected to the cardiac phase measurement sensor and are adapted to activate or deactivate operation of the time matching means for a predeterminable number of cardiac cycles. The number of cardiac cycles after a signal pulse is determined by evaluation of the measurement signal received from the cardiac phase measurement sensor.
In a preferred embodiment the pacemaker control means are additionally adapted to activate operation of the time matching means for the duration of only one cardiac cycle and for immediately subsequent deactivation. That ensures that the premature cardiac stimulation pulses are isolated, that is to say they are delivered subsequently to and followed by a predetermined number of natural cardiac periods or regularly stimulated cardiac stimulation pulses. This is to protect and carefully treat the patient as, after the production of a signal pulse, the system reverts immediately to natural cardiac activity or to regular stimulation. The duration of deactivation of operation of the time matching means is preferably between at least two and at most fifteen cardiac cycles. In an embodiment the number of cardiac cycles between two signal pulses can be altered by programming of the pacemaker control means from the exterior.
In another embodiment of the invention connected upstream of the pacemaker control means is a cardiac monitoring unit which is connected to the time measurement means and which is adapted to compare the respectively measured period duration to at least one reference cycle duration range which is contained in a reference cycle value storage means. The cardiac monitoring unit receives the measurement signal of the time measurement means, determines the period duration and compares it to the reference period duration range. In the situation where there is a deviation of the measured period duration from the reference period duration range, in a further embodiment of the invention the cardiac monitoring unit is adapted to produce a therapy warning signal which is dependent on the value of the deviation.
Preferably, the pacemaker control means are adapted to produce the deactivation signal and communicate it to the time matching means as soon as they receive a therapy warning signal from the cardiac monitoring unit. That avoids the delivery of premature cardiac stimulation pulses in such situations in which the cardiac rhythm deviates from normal values and premature cardiac stimulation pulses could trigger off or increase an arrhythmia situation.
In a further embodiment, the pacemaker control means are adapted to block the production of an activation signal for a defined period of time in the event of receiving a therapy warning signal. That ensures that pacemaker therapy which is primarily required is not interrupted by the delivery of premature stimulation pulses.
The cardiac stimulation device according to the invention has the advantage over the previously known arrangements that it can be carried into effect in many different design configurations. The particular advantages thereof can take effect in particular in a design configuration in the form of an xe2x80x9con-demandxe2x80x9d pacemaker or an integrated cardioverter-defibrillator (ICD). An embodiment of the invention is in the form of ICD and has a cardioversion unit which is adapted to produce and deliver stimulation pulses suitable for cardioversion or defibrillation, at defined moments in time. The cardioversion unit is connected to the pacemaker control means which control activation or deactivation of the cardioversion unit.
In addition, a further embodiment of the invention, for carrying out a pacemaker therapy, has a trigger unit which is connected on the input side to the cardiac phase measurement sensor and on the output side to the signal generator and which is adapted to produce and deliver cardiac stimulation pulses at defined moments in time in the context of a pacemaker therapy. In this embodiment, the pacemaker control means preferably take over co-ordination between pacemaker therapy and signaling. The pacemaker control means are connected to the trigger unit and to the time matching means and are adapted to produce and deliver at least one activation or deactivation signal to the trigger unit or the time matching means. When an activation signal is delivered to the pacemaker unit, a deactivation signal is also delivered to the time matching means. Vice-versa, when an activation signal is delivered to the time matching means, a deactivation signal is also delivered to the trigger unit. The delivery of activation and deactivation signals, for the sake of simplicity, can also be replaced by a change-over switching device which is controlled by the pacemaker control means and which selectively activates the time matching means or the trigger unit. In that case, the trigger unit is connected in parallel with the time matching means. The signal generator is therefore actuated either by way of the time matching means or by way of the trigger unit.
In an apparatus with integrated pacemaker functions, for the sake of simplicity the signaling pulses are also produced by the pacemaker unit so that here it is possible to forego a signal pulse generator which is designed specifically for the production of signal pulses.

Signaling method for an implantable cardiac stimulation device and a cardiac stimulation device

Biotronik Mess -und Therapiegeraete GmbH and Co. Ingenieurbuero Berlin


A method for preparing chromium(III) pyridine-2-carboxylate using 2-OP rectification residues, including: subjecting the 2-OP rectification residues to in-situ catalytic pyrolysis and vacuum distillation, room-temperature crystallization and separation, recrystallization and dehydration, alkali-catalyzed hydrolysis, acidification and complexation, and separation, washing and drying to prepare a chromium(III) pyridine-2-carboxylate product, of which a yield is greater than 50% of the weight of the 2-OP rectification residues. The acidification and complexation includes: cooling the aqueous solution containing sodium pyridine-2-carboxylate obtained from the alkali-catalyzed hydrolysis to a temperature below 50° C.; adjusting the aqueous solution to pH 3.0-8.5 with 5-50 wt % dilute H2SO4 or 3-30 wt % dilute HCl followed by batchwise addition of CrCl3, Cr(NO3)3 or Cr2(SO4)3 for complexation at 20-70° C. to obtain a slurry containing chromium(III) pyridine-2-carboxylate, which is separated, washed and dried to obtain a chromium(III) pyridine-2-carboxylate product with a purity of 98.5% or more.

2-OP, also chemically named 2-cyanopyridine, pyridine-2-carbonitrile and 2-pyridinecarbonitrile and with a CAS Number of 100-70-9, is a white to light brown needle-like crystal having a melting point of 24˜27° C. As an important intermediate, 2-OP has been widely used in the synthesis of various fine organic chemicals such as pharmaceuticals, agrochemicals and dyes, and most of these chemicals exhibit various excellent properties. For example, the new herbicide picloram prepared from the 2-OP has the advantages of high efficacy, good selectivity, low toxicity and small residual amount and short residual period in soil and plant, suitable for the control of the most dicotyledonous weeds and shrubs in the fields of wheat, corn and sorghum. Moreover, the 2-OP can also be used to synthesize 2-amino-5-chloropyridine which is an important intermediate in the manufacture of a novel oral anticoagulant betrixaban.
There are several methods of synthesizing the 2-OP, including catalytic 2-methylpyridine ammoxidation method, cyano substitution method, pyridine-2-carboxaldoxime method and 2-aminopyridine method. Regarding the catalytic 2-methylpyridine ammoxidation method, a mixture of nitrogen and oxygen is used as an oxidant to directly oxidize the 2-methylpyridine into the 2-OP at high temperature in the presence of a catalyst. In the cyano substitution method, 2-halopyridine is reacted with acetone cyanohydrin and an inorganic alkali metal cyanide under a certain condition to enable the substitution of the halogen atom with a cyano group to form the 2-OP. As for the pyridine-2-carboxaldoxime method, pyridine-2-carboxaldoxime is directly dehydrated in the presence of a dehydrating agent or hydrated at high temperature to give the 2-OP. In the 2-aminopyridine method, the 2-aminopyridine is diazotized to form a pyridine diazonium salt, which subsequently undergoes Sandmeyer reaction with cuprous cyanide to produce the 2-OP. The catalytic 2-methylpyridine ammoxidation method emerges from such methods and is widely used in actual production because of sufficient source, absence of highly-toxic cyanide, high safety and less cost.
There are two conversion pathways in the preparation of the 2-OP using the catalytic 2-methylpyridine ammoxidation in the presence of high temperature and a catalyst. In one pathway, 2-methylpyridine is oxidized into pyridine-2-carboxaldehyde in the presence of a catalyst, and then the pyridine-2-carboxaldehyde is reacted with ammonia to form pyridine-2-methylenimine which is dehydrogenated to produce the 2-OP. While in the other pathway, after 2-methylpyridine is oxidized into pyridine-2-carboxaldehyde in the presence of a catalyst, the pyridine-2-carboxaldehyde is continuously oxidized into pyridine-2-carboxylic acid, which is then reacted with ammonia at high temperature to form pyridine-2-carboxamide. The pyridine-2-carboxamide is subsequently dehydrated at high temperature to produce the 2-OP. Actually, in the process of preparing the 2-OP from 2-methylpyridine by catalytic ammoxidation, the oxidized product is generally required to be rectified to obtain the 2-OP with high purity, while a large amount of rectification residue is simultaneously generated, the amount of which is about 10%-15% of the 2-OP production. Currently, the residues formed in the rectification are treated as a hazardous solid waste, and are subjected to harmless treatment by high-temperature incineration and then landfilled or mineralized. However, such a treatment requires a large amount of energy and often fails to obtain the absolutely harmless rectification residues. In addition, some fine chemicals such as pyridine-2-carboxamide and pyridine-2-carboxaldehyde may exist in the rectification residues derived from the process of preparing the 2-OP from 2-methylpyridine by the catalytic ammoxidation, so the high-temperature incineration treatment may result in insufficient utilization of the residues.
Chromium(III) pyridine-2-carboxylate, also named pyridine-2-carboxylic acid chromium(III) salt, chromium(III) 2-pyridinecarboxylate, chromium(III) picolinate, tris (picolinate) chromium(III) and picolinic acid chromium(III) salt and with CAS Number of 14639-25-9, is a violet to purplish red crystalline powder, which can succeed in passing through the cell membrane and directly act on tissue cells, enhancing the activity of insulin and improving the glycometabolism.
Chromium(III) pyridine-2-carboxylate is chemically stable at room temperature, slightly soluble in water and insoluble in ethanol. Additionally, chromium(III) pyridine-2-carboxylate has electrically-neutral molecular structure and hydrophobicity, so that it can undergo the transmembrane absorption in a complete structure. The GTF (Glucose Tolerance Factor)-like structure of chromium(III) pyridine-2-carboxylate can facilitate its absorption and the exertion of its biological functions. Moreover, chromium(III) pyridine-2-carboxylate is a supplement which plays a role in strengthening muscles and losing weight, and it can also increase the amount of active AMP protein kinase (AMPK) involving in metabolic pathways in skeletal muscle cells, improving the energy balance and functions of the insulin. As a feed additive, chromium(III) pyridine-2-carboxylate can not only increase the proportion of lean meat, reduce fat content and improve the carcass quality, but also enhance the animals' anti-stress ability and immunity, thereby promoting the yield of animal products. In August 2005, the US Food and Drug Administration (FDA) approved the production of chromium(III) pyridine-2-carboxylate, and confirmed that it is safe to apply chromium(III) pyridine-2-carboxylate in the treatment of insulin resistance type II diabetes.
There are four primary methods of preparing chromium(III) pyridine-2-carboxylate. In method 1, pyridine-2-carboxylic acid is reacted with potassium hydroxide in ethanol to form potassium pyridine-2-carboxylate which is then reacted with chromium trichloride dissolved in ethanol to produce chromium(III) pyridine-2-carboxylate. In method 2, pyridine-2-carboxylic acid is reacted with sodium hydroxide in water to form sodium pyridine-2-carboxylate which is then reacted with chromium(III) nitrate to produce chromium(III) pyridine-2-carboxylate. In method 3, 2-methylpyridine is oxidized by chromic anhydride into pyridine-2-carboxylic acid in the presence of sulfuric acid and then the pyridine-2-carboxylic acid is complexed with trivalent chromium under acidic conditions to produce chromium(III) pyridine-2-carboxylate, where the excessive chromic anhydride is removed by ethanol reduction and the excess trivalent chromium is removed by alkalization. The key step in this method is to oxidize the methyl in the 2-methylpyridine into a carboxyl group. In method 4, 2-methylpyridine is oxidized by potassium permanganate into pyridine-2-carboxylic acid followed by filtration to remove MnO2 and complexation to produce chromium(III) pyridine-2-carboxylate.
The application discloses a method of preparing chromium(III) pyridine-2-carboxylate using 2-OP rectification residues, which relates to a cleaner production technology in the high-value utilization and reduction of chemical hazardous solid wastes.
In order to develop a method of preparing chromium(III) pyridine-2-carboxylate using 2-OP rectification residues, the references are made to many publications related to the preparation, application and analysis of pyridine-2-carbonitrile, pyridine-2-carboxylic acid and chromium(III) pyridine-2-carboxylate; for example, Transition metal-free synthesis of primary amides from aldehydes and hydroxylamine hydrochloride, Tetrahedron Letters, 2014, Vol. 55, No. 20; Progress in preparation of pyridinecarboxylic acids, Chemical Research and Applications, 2003, Vol. 15, No. 2; Synthesis of 3,6-dichloropicolinic acid, CIESC Journal, 2011, Vol. 62, No. 9; Electrochemical synthesis of 3,6-dichloropicolinic acid and its industrialization, CIESC Journal, 2010, Vol. 61, No. 3; Synthesis and characterization of cobalt(II) and nickel(II) complexes of 2-picolinic acid by room temperature solid-solid reaction, Fine Chemicals, 2013, Vol. 30, No. 3; Synthesis and application of nicotinic acid, Applied Chemical Industry, 2010, Vol. 39, No. 10; Study on V—Ti—O—Mo catalysts for 2-cyanopyridine synthesis via gas-solid ammoxidation, Journal of Chemical Engineering of Chinese Universities, 2016, Vol. 30, No. 4; Improvement on the technologic process of synthesis of 2-pyridinecarboxylic acid, Hubei Chemical Industry, 2001, Vol. 18, No. 2; Synthesis of 2-pyridinecarboxylic acid by oxidation with KMnO4, Chemical Research, 2010, Vol. 21, No. 1; Synthesis of 2-pyridinecarboxylic acid oxidation of potassium dichromate, Journal of Molecular Science, 2007, Vol. 23, No. 2; Technology improvement of chromium 2-picolinate, Hebei Journal of Industrial Science & Technology, 2015, Vol. 32, No. 6; Improved synthesis of chromium 2-picolinate, Feed Industry, 2001, Vol. 22, No. 5; Synthesis and biological activity of chromium pyridine carboxylates, Chemical Reagents, 2001, Vol. 23, No. 6; A new process of synthesis of chromium-2-picolinate by chromic anhydride oxidation, Chemical Engineer, 2005, No. 9; Ammonia oxidation catalytic synthesis of 2-cyanopyrazine, Journal of Chemistry and Chemical Engineering, 2005, Vol. 19, No. 6; Ammoxidation of 2-picoline catalyzed by modified V2O5/TiO2, Monatshefte für chemie-chemical monthly, 2014, Vol. 145, No. 8; Study on the technologic process of synthesis of chromium 2-picolinate, Chemical Engineer, 2004, No. 1; The preparation of isonicotinic and picolinic acids, Journal of American Chemistry Society, 1952, Vol. 74, No. 21; Studies on the conditions of synthesis of picolinic acid by heterogeneous catalytic oxidation of 2-picoline, Catalysis Letters, 1998, Vol. 54, No. 1; and Feed additive chromium picolinate, Chinese NY Industry Standard, NY/T 916-2004.

Method for preparing chromium(III) pyridine-2-carboxylate using 2-OP rectification residues


A center bowl liner is provided for use between a center plate of a railroad car and a center bowl surface on a truck bolster. The center bowl liner includes a disc-shaped element having top and bottom surfaces and a central opening for receiving a center pin. A conductive spring washer is attached to the disc-shaped element, with the conductive spring washer having a contoured profile such that portions of the conductive spring washer are exposed at the top and bottom surfaces of the disc-shaped element and create an electrical connection between the railroad car center plate and the center bowl on the truck bolster. The disc-shaped element acts as a load-bearing element generally supporting the railroad car center plate. The conductive spring washer, since it has spring-like properties, will also undertake to bear a limited amount of the load of the railroad car center plate in addition to providing an electrical connection between the car and truck.

In railroad freight cars, the center plate on the underside of the car body sits inside the center bowl on the truck bolster and is guided into position during assembly via the use of a center pin, or kingpin, that fits through the holes formed in the center bowl and the center plate. Typically, a liner is placed between the center plate and the center bowl surfaces to help reduce wear and/or modify the turning resistance of the truck. Historically, this liner has taken the form of a metallic horizontal disc that may also be used in conjunction with a metallic ring or an upstanding cylindrical wall at the outer perimeter of the disc to protect both the horizontal and vertical surface of the center bowl and center plate. However, these metal liners typically need to be lubricated periodically, which is burdensome and expensive.
In recent decades, railroad freight car builders and owners have started utilizing non-metallic horizontal or cup shaped liners. Some examples of non-metallic lines are the ultra-high molecular weight (UHMW) polyethylene and glass-filled polyester thermoplastic urethane (TPU) center bowl liners currently in the market today. These non-metallic center bowl liners can provide some benefits over traditional metallic liners, such as lower cost, ease of installation, lower coefficient of friction, reduced wear, etc. However, they are not without their own issues.
One drawback with the use of a non-metallic liner is that when a non-metallic liner is added between the car and the truck, there is no electrical continuity or conductivity between the car and the truck. Electrical conductivity between the car and the truck is important to provide a ground for the car body. Thus, use of a non-metallic liner can create an environment where static electric charge can build up in the car structure, resulting in a dangerous and unsafe condition. To combat this, manufacturers typically add a metallic or conductive material to the liner, such as metallic buttons or carbon black to provide some means of conductivity between the car and the truck to prevent the buildup of static electricity. Unfortunately, carbon black is not as conductive as metal and can be considered only an anti-static or semi-conducting material. On the other hand, while the metallic buttons provide sufficient conductivity, they can lift the car body out of the bolster bowl if they don't crush properly or they can become loose over time and fall out of the center bowl liner.
In addition, the non-metallic center bowl liner material itself is subject to failure. If the liner has a coefficient of friction that is too low, it can melt due to frictional heat generated by hunting, which is a violent oscillation of the truck relative to the car body. Furthermore, some materials, such as UHMW polyethylene, are prone to compression set, or "cold flow", when subjected to high compression loads, which can reduce the life of the component. As a result, some suppliers have chosen to add glass fibers to the non-metallic liner material to improve its compression set characteristics. However, under certain loading conditions, the glass can be abrasive and increase the rate of wear in the center bowl or center plate. Finally, UHMW polyethylene and glass-filled polyester TPU materials can become brittle and crack at low temperatures.
The present invention is directed toward overcoming one or more of the above-mentioned problems.

Center bowl liner with spring washer conductor