1. Field of the Invention
The invention relates to a cryogenic fluid pump that is capable of continuously recirculating a cryogenic fluid for several weeks without user intervention.
2. Background of the Invention
Liquid nitrogen and other cryogenic liquids are used in a variety of scientific applications to cool experimental systems. For instance, cryogenic liquids provide favorable kinetics, confer improved vacuum conditions, and reduce the amount of contaminants in experimental procedures.
Some experiments require a constant flow of a liquid cryogenic at a low rate. A “low rate” is generally considered to be a rate less than 10 L/min. Many currently available cryogenic pumps are unsuitable for continuous operation at this rate. Further, not all pumps can be adapted to operate at a flow rate lower than their designed flow rate. Centrifugal pumps in particular are not designed to operate at rates much higher or lower than their manufacturer's stated best efficiency flow rate. Therefore, providing a steady stream of cryogenic liquid to some experiments is a challenge.
One example in which this cryogenic pumping challenge is particularly acute is ion-trapping experiments, such as Paul Traps. In Paul Traps, buffer gases are used to aid in ion transport and confinement. Bringing the buffer gas from room temperature to the temperature of a cryogenic liquid significantly reduces the spatial spread of trapped ions and improves the gas purity in the cooling region. These improvements increase the trap storage times. Longer trap storage times would allow for more accurate observation of the trapped ion. In some instances, meaningful observation can take days or weeks, but providing the small, constant flow of cryogenic liquid required for these long-term experiments has proven difficult.
Typically, the cryogenic liquid is continuously pumped by self-pressurization into the experimental setup and then lost downstream. Self-pressurization pumps use the increasing gas pressure caused by the boiling liquid inside the sealed Dewar container to push the liquid downstream. The pressure gradient driving the flow is lost in conventional methods during attempts to re-collect the liquid. Recirculation requires liquid to flow both into and out from the reservoir, but self-pressurization pumps can only support outward flow. Since the cryogenic liquid cannot be recovered, a very large supply of cryogenic liquid is required for the duration of the experiment. Obtaining and maintaining such a large supply of cryogenic liquid can be difficult, especially in small laboratory setups. Additionally, it also wastes material and effort.
Supplying the cryogenic liquid to the experimental device also provides its own difficulty. Because cryogenic liquids are boiling, they cannot be pulled through a circuit by a downstream pump. Instead, they must be driven by a positive-pressure device that is submerged in the liquid. The types of positive-pressure devices that can withstand cryogenic temperatures are limited to centrifugal pumps inasmuch as such pumps do not contain flexible components that become brittle when exposed to extreme cold. However, centrifugal pumps are susceptible to cavitation, which is further exacerbated by the fact that cryogenic liquids are constantly boiling.
Cavitation occurs when vapor cavities, i.e., gas bubbles, form in a liquid as a result of forces acting on the liquid and subsequently collapse against the impeller vanes. One prominent reason for cavitation is the rapid change of pressure in the liquid, such as when a liquid experiences a steep pressure drop when it reaches the eye of the impeller in a pump. The pressure drop is caused by a decrease in flow area, which causes an increase in flow velocity. Cavitation in a pump causes large amounts of noise, vibration, pressure pulsation, degradation of pump components, and loss of efficiency. If the pump chamber is sufficiently filled with gas bubbles, the flow of liquid will cease entirely.
The problems of pump cavitation are further exacerbated if a continuous flow at a low rate is desired or if the flow resistance is high. Evaporation of the cryogenic liquid in the flow circuit creates high flow resistance. Therefore, a need exists in the art for a cryogenic liquid pump that is capable of providing continuous flow for a period of days, weeks, or months at a low flow rate without the attendant cavitation problems that beset other pumps.
State of the art liquid nitrogen pumps are commercially available. However, these pumps are large and extremely expensive. Further, they are unsuitable for cooling small laboratory equipment.
Thus, a further need exists in the art for a compact cryogenic pump that is relatively inexpensive and is suitable for small-scale laboratory experimentation. The pump should also supply cryogenic fluids at rates less than 10 L/min.
An object of the present invention is to address the deficiencies of state of the art liquid nitrogen pumps.
A further object of the present invention is to provide a cryogenic liquid pump that can operate continuously for days, weeks, or months. A feature of the present invention is that the pump contains a gas release plate. An advantage of the present invention is that the onset of cavitation is delayed because the gas bubbles in the pump's impeller are vented. Another feature of the present invention is that the pump impeller is fed by an inducer. An advantage of the present invention is that the inducer increases the local boiling point of the cryogenic liquid at the impeller by increasing the pressure on the cryogenic liquid, thereby preventing the formation of gas bubbles.
Another object of the present invention is to provide a cryogenic liquid pump that can cycle and recirculate a cryogenic liquid during a lengthy experimental procedure. A feature of the invention is that it provides a means for continuously refilling the Dewar container such that fluid pressures are maintained and do not drop within the pump. An advantage of the present invention is that a large store of cryogenic liquid is not necessary to maintain operation of the pump. A further advantage of the present invention is that small laboratories do not need to undertake the cost of building and maintaining large stores of cryogenic liquid. A still further advantage is that small laboratories do not need to devote a large portion of their supply of cryogenic liquids to a single experiment. Rather, the invented device and method can supply a plurality of systems requiring cryogenic fluid for extended periods of time, inasmuch as the capability for doing this is limited only by the fluid resistance of each circuit and the flow rates required by each system.
Still another object of the present invention is to provide a cryogenic liquid pump that can be used for small-scale laboratory experimentation. A feature of the present invention is that it is able to provide continuous flow at a low rate (approximately 2 L/min) while maintaining a pump head of two to three meters. An advantage of the present invention is that the pump is relatively small, powerful, and inexpensive compared to other state of the art cryogenic pumps.
Another object of the present invention is to provide a centrifugal pump that can operate over a relatively wide range of flow rates. A feature of the present invention is that it can operate at a flow rates between about 11 L/min and about 0.1 L/min by varying the voltage input to the motor. Another feature of the present invention is that the gas release plate allows the pump to operate at lower flow rates. Typically, when centrifugal pumps operate at a flow rate below their best efficiency point, the pumping power is converted to thermal energy because the liquid remains in the pump housing, and as a result, the temperature of the liquid in the pump housing will rise. An advantage of the present invention is that the cryogenic liquid in the Dewar container cools the liquid in the pump housing, and while some of the liquid will vaporize, the gas release plate removes the bubbles from the pump housing.
Yet another object of the present invention is to provide a cryogenic pumping system that can operate uninterrupted without technician intervention. A feature of one embodiment of the present invention is that the Dewar container storing the cryogenic liquid contains a level sensor. The level sensor triggers a valve on an exterior reservoir to replenish the Dewar container when the cryogenic liquid level falls below a certain point. An advantage of the present invention is that a technician does not need to constantly monitor the liquid level in the Dewar container to see if evaporation or leaks have reduced the liquid level to a point of insufficiency.
Briefly, the invention provides a cryogenic liquid pump system, said pump system comprising a first end having at least an insulating lid and motor; a second end, wherein the second end is a pump, said pump comprising an impeller; and a gas release plate upstream of the impeller; and a shaft disposed between the first end and the second end, wherein the motor imparts mechanical energy to the pump through the shaft.
Also provided is a method for preventing cavitation of a cryogenic liquid in a cryogenic pump, the method comprising constantly maintaining pressure on the liquid.
The invention together with the above and other objects and advantages will be best understood from the following detailed description of the preferred embodiment of the invention shown in the accompanying drawings, wherein:
The foregoing summary, as well as the following detailed description of certain embodiments of the present invention, will be better understood when read in conjunction with the appended drawings.
As used herein, an element step recited in the singular and preceded with the word “a” or “an” should be understood as not excluding plural said elements or steps, unless such exclusion is explicitly stated. Furthermore, the references to “one embodiment” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property.
The present invention is directed to a compact cryogenic pump. The pump is designed to work at rates less than 10 L/min, and as low as 0.1 L/min.
In Paul Trap experiments, the cryogenic pump has allowed for the establishment of longer trap times. As compared to previous methods, trap storage time were increased by several orders of magnitude from milliseconds to minutes or longer. The longer trap storage times made the observation of some previously unobservable ions possible. Trap times of two to five minutes were sufficient for the collection of data for all experiments run, but longer trap times are easily attainable.
Other experiments that can benefit from the small, constant flow of cryogenic liquids provided by the present invention include: (1) cooling of gas targets for heavy-ion reactions; (2) performing online experiments involving particle beams, such as experiments involving the Advanced Photon Source x-ray beam, the Argonne Tandem Linac Accelerator System, and other particle beams found in laboratories around the world; (3) operating certain semiconductor devices that only operate in cryogenic environments; (4) conducting superconductor research; and (5) studying the effects of cryogenic exposure on protein, cells, tissues, and other biologic material.
As can be seen in
The Dewar container used in the present invention is a standard type Dewar container. Two different sizes were used in separate devices, to prove the concept. As such, the dimensions of the containers are merely illustrative and should not be construed as limiting the application of the device and method to other containers. For example, the first device had an outside diameter of about 10.38 inches, while the second device had an outside diameter of about 9.25 inches. Both Dewar containers were CF Series containers, manufactured by Cryofab, Inc. (Kenilworth, N.J.).
Motor/Lid Detail
The first end 12 of the device 10 not only contains the motor 16 to drive the pump 18, but it also contains a lid 24 (
As shown in
Alternatively, the lid 24 rests substantially flat on the lip defining the open proximal end 22p of the Dewar container 22.
The lid 24 can be seen in
As can be seen in both
At the center of the lid 24 is a region forming a center transverse aperture 36a. The center transverse aperture 36a is adapted to slidably receive the shaft 20, so as to allow the shaft to pass through the lid into the interior of the Dewar container 22. On the second or bottom surface 24b of the lid 24, the aperture 36a is surrounded by a countersunk annular groove or recessed ring 37 that has a slightly wider diameter than the aperture 36a. The recessed ring 37 aids in assembly of the device 10, and its purpose is discussed infra. Encircling, but spatially and radially disposed from the aperture 36a is a plurality of through holes 38a, such that the holes extend transversely through the lid. The through holes 38a aid in assembly of the first end of the device, which is described in detail below. The through holes 38a are preferably spaced equidistantly in a circle around the aperture 36a. In the embodiment depicted in
Below the lid 24 is an insulator disc 40, shown in
The insulator disc 40 is made of a thermally insulating material. PVC hard foam is a suitable material for the insulator disc 40 because of its superior insulation properties and because it is relatively inexpensive. In an embodiment of the invention, the insulator is removably attached to the lid.
The insulator disc 40 serves a multitude of purposes. Primarily, the insulator disc 40 prevents heat transfer between the lid 24 and the interior of the Dewar container 22. (Heat can crack the lid, lead to a build-up of ice, and accelerate the loss of cryogenic liquid.) Additionally, the insulator disc 40 prevents the extremely cold temperatures of the cryogenic liquid in the Dewar container 22 from affecting the motor 16. Furthermore, the insulator disc 40 frictionally engages the interior of the Dewar container 22, ensuring that the lid 24 snugly and evenly covers the open end of the Dewar container 22.
An alignment canister 42 rests upon, so as to be supported by, the lid 24. The alignment canister 42, as depicted in
As shown in
Extending upwardly from the periphery of the floor 42b is an axially extending perimeter wall 44 with an interior surface 44a and an exterior surface 44b. The distance between the interior surface 44a and the exterior surface 44b defines the thickness of the wall 44. At the top 42a of the canister 42, the thickness of the wall 44 defines a flat shelf surface 46. The perimeter wall 44 contains a plurality of windows 48 that extend through the thickness of the wall. These windows 48 provide access to the interior of the canister 42 during assembly of the device 10. The windows 48 also permit monitoring of the top bearing and motor shaft and allow water to easily evaporate from the inside of the alignment canister 42. As depicted in
As depicted in
The alignment plate 52 features a central passage 53 that accommodates insertion of the motor's driveshaft. Circumscribing the central passage 53 in the alignment plate 52 is a plurality of mounting points 58, which allow for the motor 16 to be mounted to the alignment plate 52. As depicted in
The motor 16 can be any suitable motor for pumping applications. Preferably, the motor 16 is DC-driven so that the pump speed can easily be controlled by an adjustable DC power supply; however, AC-driven motors can also be used with the present invention. The inventors have found that a 26 frame PMDC motor (24V), available from Bison Gear & Engineering Corp. (St. Charles, Ill.), to be a suitable motor for the present invention. Supplying the motor with a voltage of 20V, flow rates as high as about 11 L/min were achieved with a pump head of approximately 0.4 m. At about 10V, flow rates as low as about 0.1 L/min were attainable with a pump head of about 1.2 m. At about 15V, the pump could operate at flow rate of about 1.5 L/min while maintaining a pump head of about 2 m. As with typical centrifugal pumps, pump head decreased with increasing flow rates at all voltages.
As shown in
The motor 16 has a first end 16a and a second end 16b. At the first end 16a, the motor is electrically connected to a power source. The second end 16b features a drive shaft 62 that is mechanically coupled to the shaft 20.
Shaft Detail
As can be seen in
Surrounding the shaft 20 is a conduit serving as a support tube 64. The support tube 64 slidably receives the shaft 20. As can be seen in
As can be seen in
Spatially disposed of the proximal end 64p of the tube 64 is an upper flange 66. The upper flange 66 anchors the pump 18 to the first end 12 of the device 10. The upper flange 66 also maintains the coaxial arrangement of the axis of the alignment canister 42 with the support tube 64, while a lower flange 68 maintains the coaxial arrangement of the alignment canister 42 with the components of the pump 16 below. Thus, alignment among the motor 16, shaft 20, and pump 18 is ensured.
The upper flange 66 (depicted in
The lower flange 68 (depicted in
The upper flange 66 and the lower flange 68 are welded, or otherwise joined, to the support tube 64. The upper flange 66 is welded in a position spatially disposed of the proximal end 64p of the support tube 64 so that the support tube can be inserted through the insulator disc 40 and partially into the lid 24. The lower flange 68 is welded such that the distal end 64d of the support tube 64 is flush with the bottom surface of the lower flange 68.
Pump Detail
The pump 18 is comprised generally of a pump housing 72, an impeller 74, an inducer 76, a gas release plate 78, and a lower bearing plate 80.
The pump housing 72, as depicted in
Surrounding the first opening 84 is a proximal surface 88 as shown in
As discussed supra, the interior region of the pump housing 72 features a first cylindrical section 92 in fluid communication with a frustoconical section 94, which is in fluid communication with a second cylindrical section 96. The first cylindrical section 92 has the same diameter as the first opening 84. The second cylindrical section 96 has the same diameter as the second opening 86. The frustoconical section 94 tapers in diameter from the first cylindrical section 92 to the second cylindrical section 96. Further, as shown in
The first cylindrical section 96 is adapted to receive the impeller 74, such that the section 96 substantially encircles the impeller. The structure of the impeller 74 can be seen in
At the center of the disc 98, a collar 102 extends axially from the surface of the disc 98. The collar 102 accommodates the narrower portion 63 of the shaft 20. A keyway 104 is formed into the interior of the collar 102. The keyway 104 is a semi-cylindrical, recessed channel that accommodates that complements the keyway 65 on the narrow portion 63 of the shaft 20. A cylindrical key is inserted between the complementary keyways 65, 104 so as to provide a means for transferring mechanical energy created in the motor 16, through the shaft 20, and finally to drive the impeller 74. A longitudinally extending region of the collar forms a threaded aperture 105 adapted to receive a screw for frictional engagement with an opposing surface of the shaft. This screw, upon so engaged, reversibly fastening the impeller to the shaft so as to prevent the impeller from traveling along the shaft in the pump housing. The keyways, key, and screw provide a means to hold the shaft, impeller and inducer together and in registration.
As stated supra, cavitation is the most prominent reason for cryogenic pump failure. The present invention substantially reduces the problem of cavitation in two ways. First, an inducer 76, placed below the impeller 74 and within the second cylindrical section 96 of the housing 72, increases the pressure on the cryogenic liquid at the impeller 74, preventing the formation of gas bubbles. Second, the gas release plate 78 is placed above the impeller 74 to allow any gases generated at the impeller to flow away from the pump without obstructing flow of the cryogenic liquid out of the pump 18.
The inducer 76 is a screw conveyer that forces the cryogenic liquid into the impeller region of the pump. As depicted in
The second feature responsible for the reduction in cavitation is the gas release plate 78. As depicted in
Over time some gas bubbles will inevitably form in the impeller region of the pump. In order to preserve the functioning of the pump, those gas bubbles must be allowed to escape from the impeller 74. Thus, the gas release plate 78 provides a means of egress the gas bubbles from the interior of the pump without obstructing the liquid port 97.
Operation of the gas release plate 78 is facilitated by additional spaces provided above and below the gas release plate 78 as shown in
Once the gas bubbles reach the wall of the first cylindrical section 92, their relative density allows them to float upwardly through the first space S1 between the central disc 98 of the impeller and the wall of the first cylindrical section 92. The gas bubbles then move transversely through the third space S3 until they reach the shaft 20. The transverse flow of the bubbles results from the pressure gradient formed above the impeller as a result of the frictional forces between the impeller and the liquid. The centrifugal forces cause the pressure gradient to point radially away from the shaft. Because the bubbles are less dense than the liquid, they flow opposite the direction of the pressure gradient. The bubbles again move upwardly through the second space S2 and then transversely across the fourth space S4, thereby exiting the pump housing 72.
The final component of the pump 18 is the lower bearing plate 80. As shown in
Assembly and Operation
To assemble the first end 12 of the device 10, the insulator disc 40, lid 24, and alignment canister 42 are arranged such that the through holes 38a-c and central apertures 36a-c align or are otherwise in registration. These components are then temporarily joined using a fastener, such as a bolt and a nut. Alignment of the through holes 38a, 38b and apertures 36a, 36b in the lid 24 and the insulator disc 40 will bring the openings 32a, 32b and recesses 34a, 34b into alignment as well, which is important for operation of the device. The first bearing 45 is placed in the groove 43 formed into the floor 42b of the alignment canister 42.
The drive shaft 62 of the motor 16 is inserted through the central passage 53 of the alignment plate 52. The mounting points 61 in the mounting plate 60 are aligned with the mounting points 58, and the motor 16 and the alignment plate 52 are secured together. The alignment plate 52 is then attached to the alignment canister 42, using fasteners, such as screws, bolts, or pins, inserted through the holes 56 in the alignment plate into the coupling points 50 formed into the flat shelf surface 46 of the alignment canister 42.
The shaft 20 is inserted into the welded support tube 64, upper flange 66, and lower flange 68 combination. The shaft 20 and support tube 64 are then inserted into the central apertures 36a-c of the insulator disc 40, lid 24, and alignment canister 42 until the upper flange 66 abuts the insulator disc 40 and the proximal end 64p of the support tube 64 abuts the recessed ring 37. The fasteners are inserted through the through holes 38d in the upper flange 66, and the lid 24, insulator disc 40, alignment canister 42, and upper flange 66 are firmly secured together. The shaft 20, being freely movable within the support tube 64, is brought into close proximal relation to the driveshaft 62 of the motor 16.
The shaft 20 and drive shaft 62 are loosely coupled together using a flexible coupling 117, such as the double beam clamp, manufactured by Lovejoy, Inc. (Downers Grove, Ill.). The double beam clamp has two screw clamps at either end of the coupling. The first clamp attaches to the drive shaft 62, while the second clamp attaches to the shaft 20. The tightness of the clamps can be adjusted using Allen wrenches on the screws. When the driveshaft 62 and shaft 20 are first joined at the coupling 117, they are loosely held together so that the shaft positioning can be adjusted during assembly of the second end 14 of the device 10. The windows 48 in the alignment canister 42 allow for the assembler to manipulate the shaft 20, driveshaft 62, and coupling 117.
To assemble the second end 14 of the device 10, bolts, screws, or other fastening means are inserted in the through channels 70a in the lower flange 68. Then, the second bearing 116 is inserted into the second groove 114 in the lower bearing plate 80. The central aperture 36g and the through channels 70d are aligned with the shaft 20 and fastening means, respectively, and the lower bearing plate 80 is slid onto the shaft 20 and fastening means until the lower bearing plate 80 abuts the lower flange 68. Washers are placed on each fastening means, and the gas release plate 78 is then slid onto the shaft 20 and fastening means until it abuts the washers. The washers establish the fourth space S4 between the lower bearing plate 80 and the gas release plate 78 for escape of gases that accumulate in the pump housing 72. In one embodiment of the invention, the washers are approximately thirty mils in thickness. The gas release plate 78 is temporarily fixed in that position by securing a locking device, such as a nut, to each fastening means and tightening them until the locking device firmly hold the gas release plate in position.
Next the impeller 74 and inducer 76 are attached to the narrow portion 63 of the shaft 20; the keyways 65, 104 are aligned; the key inserted into the cylindrical channel created by the keyways 65, 104; and the impeller 74 and inducer 76 are locked into place. At this point, because the shaft 20 was only loosely coupled to the driveshaft 62, the vertical positioning of the shaft 20 can still be adjusted in the support tube 64. The shaft 20 is adjusted until the third space S3 is established between the impeller disc 98 and the gas release plate 78. In one embodiment, the third space S3 is approximately eight mils. The use of shims can facilitate placement of the impeller 74 relative to the gas release plate 78. When the desired spacing is provided, the shaft 20 is locked into place by firmly securing the clamps on the coupling 117.
After securing the impeller in place, the locking devices that were temporarily holding the gas release plate in place are removed. Finally, the pump housing 72 is placed on the end of the shaft 20 around the inducer 76 and impeller 74. The fastener means are inserted through the through channels 70a-d, and the fastening means is securely locked into place so as to join the second end 14 components together. Thus, the pumping device 10 is assembled. The assembled second end 14 can be seen in
As can be seen in
When the motor 16 is electrically powered, the driveshaft 62 is rotated, which thereby rotates the shaft 20. Since the shaft 20 and the impeller 74 and inducer 76 are mechanically coupled, the impeller 74 and inducer 74 will also rotate. Rotation of the inducer 76 draws pressurized cryogenic liquid into central region of the impeller 74. The impeller 74 accelerates the fluid outwardly to the perimeter of the impeller disc 98 where it enters the liquid port 97 and travels up the cryogenic conduit 118. The key, described supra, assures that the inducer and impeller rotate at the same angular velocity.
The cryogenic conduit 118 runs through the insulator disc 40 and the lid 24 through the openings 32a, 32b. On the top surface 24a of the lid 24, the conduit 118 is held in place with a lid bracket 120. As shown in
The cryogenic conduit 118 supplies cryogenic liquid to a device, experiment, or other apparatus. After flowing through the device, experiment, or other apparatus, the distal end of the same cryogenic conduit or a second length of cryogenic conduit directs flow back into the Dewar container 22.
The presently invented pumping device is capable of providing continuous recirculation of liquid nitrogen for up to six weeks, while operating at 2400 rpms and delivering 2 L/min of liquid nitrogen. Under those parameters, the pump is capable of sustaining a pump head of three meters.
During operation, especially operation over the course of several weeks, some cryogenic liquid will be lost due to evaporation and leaks. In one embodiment of the invention, a level sensor, such as a thermal diode, is placed in the Dewar container. (In this embodiment, the thermal diode turns an electric current on or off, depending on whether it is in contact with liquid nitrogen.) When the liquid drops below a certain level, the sensor triggers an outside reservoir to pump more cryogenic liquid into the Dewar container until the requisite fill level is met. The cryogenic liquid is pumped in through a cryogenic conduit that runs through an opening in the lid. In this embodiment, the lid 24 contains six openings 32a with two being for entry and exit of the cryogenic conduit, one for insertion of the level sensor, and one for insertion of the cryogenic conduit from the reserve tank. The remaining two openings are for ventilation and visual inspection.
In another embodiment, the device 10 supplies cryogenic liquid to multiple experiments at one time. The total resistance of the flow in the circuit is the only factor that limits the number of experiments that can be tied to a single pump.
The pump as described was constructed of materials that could withstand cryogenic temperatures. The inventors recommend aluminum 6061 for the components that are submerged in the cryogenic liquid. The support tube, lower flange, and upper flange were made of type 304 stainless steel. The aluminum and stainless steel materials were selected not only for their ability to withstand cryogenic temperatures but also because they experience similar material contractions at cryogenic temperatures. The lid was made from acetal resin, which is a highly crystalline polymer with excellent strength and low temperature properties. Stainless steel bearings, lubricated with graphite were used for the first and second bearings. The bearings are commercially available from Barden Corporation (Danbury, Conn.).
It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. While the dimensions and types of materials described herein are intended to define the parameters of the invention, they are by no means limiting, but are instead exemplary embodiments. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. § 112(f) unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.
The present methods can involve any or all of the steps or conditions discussed above in various combinations, as desired. Accordingly, it will be readily apparent to the skilled artisan that in some of the disclosed methods certain steps can be deleted or additional steps performed without affecting the viability of the methods.
As will be understood by one skilled in the art, for any and all purposes, particularly in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as “up to,” “at least,” “greater than,” “less than,” “more than” and the like include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. In the same manner, all ratios disclosed herein also include all subratios falling within the broader ratio.
One skilled in the art will also readily recognize that where members are grouped together in a common manner, such as in a Markush group, the present invention encompasses not only the entire group listed as a whole, but each member of the group individually and all possible subgroups of the main group. Accordingly, for all purposes, the present invention encompasses not only the main group, but also the main group absent one or more of the group members. The present invention also envisages the explicit exclusion of one or more of any of the group members in the claimed invention.
The U.S. Government has rights in this invention pursuant to Contract No. DE-AC02-06H11357 between the U.S. Department of Energy and UChicago Argonne, LLC, representing Argonne National Laboratory.
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5819544 | Andonian | Oct 1998 | A |
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6230516 | Andonian | May 2001 | B1 |
20110152849 | Baust | Jun 2011 | A1 |
20130183155 | Stoicescu | Jul 2013 | A1 |
20130263608 | Thornton-Wood | Oct 2013 | A1 |
Number | Date | Country | |
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20160061384 A1 | Mar 2016 | US |