Patent Application
20120053339
The invention relates to the field of microbial polymers. In particular, the invention relates to xanthan gum having improved properties such as enhanced hydration tolerance, faster hydration and higher viscosity.
Xanthan gum is a polyanionic polysaccharide used as a thickening, emulsifying and/or stabilizing agent in industrial (including construction, paints, paper, textiles, plant-protection, water-treatment and petroleum industries), food, cosmetic, agro-chemical and pharmaceutical formulations. Xanthan gum is produced commercially by aerobic fermentation of a bacterium Xanthomonas campestris.
Xanthan gum is generally supplied in a dry, powder form. Prior to use in a particular application, the xanthan gum is usually hydrated in an aqueous solution. In many cases, the solution used for hydration contains ions or other dissolved materials, which inhibit or even prevent full hydration of the xanthan gum. In those cases, the hydration medium has to be adjusted so as to contain lower levels of dissolved materials. When this adjustment is not possible, the effective use of xanthan gum might not be possible.
When hydrating xanthan gum in any medium, some time has to be allowed for the solvent to penetrate the dry powder, swell it and then allow it to diffuse into the hydration medium. This process takes time and requires mixing to continue until full hydration is obtained. If the mixing is stopped before the xanthan gum is fully hydrated a number of problems, including low viscosity result. A few techniques have been suggested to increase hydration including irradiating non-irradiated xanthan gum with ionizing radiation or providing a dry powder having a particle size of 60 to 250 microns with a mean diameter of 100-200 microns. However, the former results in an increase in product costs of the xanthan gum, and the latter fails to address the need for higher viscosity discussed below.
Since xanthan gum is often used as a thickener or suspending aid, many applications would benefit from having a xanthan gum that produces higher viscosity solutions either to provide more stability at the same use level or reduce the use level of xanthan gum and retain the same degree of stability. Thus, there have been many attempts to manufacture xanthan gum which when in solution exhibits a higher viscosity. One such method is heat treating (i.e. pasteurizing) the fermentation broth. This heat treatment leads to a conformational change which in turn results in a xanthan gum that produces solutions with a higher viscosity. However, this method can also result in impaired gum hydration due to the changes brought about by heating. Genetic manipulation of the xanthan organism such as over-expression of the gumB and gumC genes can result in higher viscosity solutions without pasteurization. However, genetically-modified products are not acceptable in many countries.
For the reasons discussed above, it would be advantageous to develop a powdered xanthan gum which when in solution can hydrate in a wide range of media, hydrate in a short period of time compared to conventional xanthan gum, and also provide a higher viscosity than traditional xanthan gum.
The present invention provides a xanthan gum, and methods of making thereof, having more or more following properties in solution: (a) a Low Shear Rate Viscosity (LSRV) at 3 rpm of greater than about 1600 mPa·s (cP) when hydrated in standard tap water at a 0.25 weight percent (wt %) concentration of xanthan gum; (b) a Sea Water Viscosity (SWV) of greater than about 18 at 1 pound/barrel when hydrated in synthetic sea water; (c) a Hydration Rate of less than about 3 minutes in a 1 wt % NaCl solution at a 1 wt % concentration of xanthan gum; and (d) an ability to essentially fully hydrate in less than about 10 minutes in a 6 wt % NaCl solution at a 1 wt % concentration of xanthan gum.
In certain embodiments, the inventive xanthan gum exhibits properties comprising a Low Shear Rate Viscosity (LSRV) at 3 rpm of greater than about 1800 mPa·s (cP) when hydrated in standard tap water at a 0.25 weight percent (wt %) concentration of xanthan gum; a Low Shear Rate Viscosity (LSRV) at 3 rpm of greater than about 1750 mPa·s (cP) in a 0.01M NaCl solution at a 0.25 weight percent (wt %) concentration of xanthan gum; and/or a Low Shear Rate Viscosity (LSRV) at 3 rpm of greater than about 1700 mPa·s (cP) in a 0.1M NaCl solution at a 0.25 weight percent (wt %) concentration of xanthan gum.
In certain embodiments, the inventive xanthan gum exhibits properties comprising a Sea Water Viscosity (SWV) of greater than about 20 at 1 pound/barrel when hydrated in synthetic sea water. In certain embodiments, the inventive xanthan gum exhibits properties comprising a Hydration Rate of less than about 2 minutes in a 1 wt % NaCl solution at a 1 wt % concentration of xanthan gum, or less than about 4 minutes in a 3 wt % NaCl solution at a 1 wt % concentration of xanthan gum, or less than about 6 minutes in a 3 wt % citric acid solution at a 0.4 wt % concentration of xanthan gum. In certain embodiments, the inventive xanthan gum exhibits properties comprising an ability to essentially fully hydrate in less than about 8 minutes in a 6 wt % NaCl solution at a 1 wt % concentration of xanthan gum, or fully hydrate after about 1 hour of proper mixing at 1800 rpm under ambient conditions in a 10 wt % ammonium nitrate solution at a 0.2 wt % concentration of xanthan gum.
The inventive xanthan gum further exhibits properties comprising a viscosity, as measured using a Brookfield Model LV viscometer, No. 1 Spindle, at 3 rpm, after one hour of mixing at 1800 rpm under ambient conditions of greater than about 1900 mPa·s when hydrated in a 0.01M or 0.1 M NaCl solution at a 0.25 wt % concentration of xanthan gum; or greater than about 2100 mPa·s when hydrated in a 0.01 M or 0.1M NaCl solution at a 0.25 wt % concentration of xanthan gum.
The present invention further provides that the inventive xanthan gum is obtained from the fermentation of an Asian Xanthomonas campestris strain, i.e., Xanthomonas campestris pathover campestris, deposited with the American Type Culture Collection (ATCC) under the Accession No. PTA-11272. The present invention further provides that the inventive xanthan gum can be used as a thickener, viscosity modifier, emulsifier, or stabilizer in formulations for the drilling for or the assisted recovery of petroleum, for water treatment, for food, cosmetics, pharmaceutical or agrochemical formulations, for industrial or household cleaning, or for paper, construction, or textiles.
Among other things, the present disclosure provides a xanthan gum polymer (“xanthan gum”) which exhibits unique characteristics when incorporated into various solutions. Xanthan gum is an extracellularly produced biogum made in aerobic fermentation by the bacteria Xanthomonas campestris. In one aspect, the organism used in the fermentation to produce the inventive xanthan gum is a strain of Xanthomonas campestris pathovar campestris. The fermentation requires a nitrogen source, a carbon source and other appropriate nutrients well known to those skilled in the art. During fermentation, the dissolved oxygen levels and temperature are maintained so as to provide the desired or optimal growth conditions for the bacteria.
The disclosure also provides for a xanthan gum which exhibits unique hydration and viscosity properties when in solution while maintaining typical xanthan gum properties with respect to, for example, enzyme stability and shear stability. The performance of xanthan gum in solutions may be measured by many different techniques under varying conditions of shear rates, polymer concentrations and hydration media. Regardless of the conditions, the inventive xanthan gum yields solutions which have viscosity values equal to and in most cases greater than previously known xanthan gums and has the ability to either hydrate faster or fully hydrate as compared to previously known xanthan gums. Thus, to quantify the performance of the inventive xanthan gum over the previously known xanthan gums various testing conditions are defined below and properties measured.
In one aspect, the xanthan gum when in solution exhibits properties comprising (i) a Low Shear Rate Viscosity (as defined below) at 3 rpm of greater than about 1600 mPa·s (cP) when hydrated in standard tap water (defined below) at a 0.25 weight percent (wt %) concentration of xanthan gum, (ii) a Sea Water Viscosity (as defined below) of greater than about 18 at 1 pound/barrel when hydrated in synthetic sea water, (iii) a Hydration Rate (as defined below) of less than about 3 minutes in a 1 wt % NaCl solution at a 1 wt % concentration of xanthan gum, and (iv) the ability to essentially fully hydrate in less than about 10 minutes in a 6 wt % NaCl solution at a 1 wt % concentration of xanthan gum.
In a further aspect, the xanthan gum provided herein when in solution exhibits any one or any combination of the following properties:
The terms “fully hydrate”, “essentially fully hydrate”, “full hydration”, “100% hydration”, and the like as used herein mean that the solution has a homogeneous appearance such that there is an absence of particles that are visible to the unaided human eye (as shown in
In another aspect, when the xanthan gum is hydrated in standard tap water to a 0.25 wt % concentration of xanthan gum, the resulting solution has a Low Shear Rate Viscosity at 3 rpm of greater than about 1800 mPa·s. In still another aspect, when hydrated in standard tap water to a 0.25 wt % concentration of xanthan gum, the solution has a Low Shear Rate Viscosity at 3 rpm of greater than about 2000 mPa·s. Representative data are provided in
In other aspects, the inventive xanthan gum exhibits properties of a Sea Water Viscosity of greater than about 20 at 1 pound/barrel and still further of a Sea Water Viscosity of greater than about 22 at 1 pound/barrel. Representative data are provided in
In most applications, xanthan gum powder requires hydration before its use. In general terms, hydration can be considered a two step process. The first step that generally precedes the actual hydration step involves dispersing the xanthan gum in the desired medium so that individual particles are separated and not lumped together or aggregated. When xanthan gum particles stick and lump, hydration typically is much slower. Generally following this breakdown of aggregates, the second step occurs when these dispersed xanthan gum particles are actually hydrated in the medium, which means that the individual polymer molecules are released from the dry particle and are free to move in the medium. The industry terms of “dispersion” and “hydration” are used to describe these first and second steps, respectively.
Hydration itself has at least two aspects. One aspect of hydration concerns how rapidly the xanthan gum particles can swell and subsequently free the polymer chains, which has been defined herein as Hydration Rate. Quick and complete hydration can be important to many applications such as dry mixes. The second aspect of hydration concerns what type of medium will allow full hydration. Some hydration media are more difficult for the individual polymer molecules to be released from the dry particle and therefore, to fully hydrate in. For example, these more “difficult” media are usually high in salts, low in pH, and/or have high levels of dissolved non-ionic solids (such as sucrose or sugar alcohols) present. When the hydration medium is sufficiently difficult for the individual polymer molecules to hydrate in, then the gum particles are not able to swell and fully release the polymer. In such instances, excessive mixing, heat or a change in hydration medium may be required to use the polymer. In one aspect, one feature of the inventive xanthan gum is its ability to fully hydrate in these difficult media, including those that may be high in salts, low in pH, and/or have high levels of dissolved non-ionic solids, as compared to conventional xanthan gum. This aspect highlights a distinct disadvantage common in conventional xanthan gum, a disadvantage that the inventive xanthan gum overcomes. Since the types of media and the definition of “difficult” media are varied, one skilled in the art will appreciate that the inventive xanthan gum is being defined based on the properties that it exhibits is certain defined media.
With respect to Hydration Rate, the inventive xanthan gum has solution properties, as follows. In one aspect, the xanthan gum has a Hydration Rate of less than about 3 minutes (as noted above), less than about 2.5 minutes, less than about 2 minutes, or less than about 1.5 minutes in a 1 wt % NaCl solution at a 1 wt % concentration of xanthan gum (
In a further aspect, the inventive xanthan gum can be more tolerant of difficult hydration media. An example of this aspect is shown in
Further, the inventive xanthan gum is able to obtain full hydration in about 1 hour of propeller mixing at 1800 rpm under ambient conditions in a 10 wt % ammonium nitrate solution at a 0.2 wt % concentration of xanthan gum (3 rpm viscosity of 5000 mPa·s, Brookfield No. 1 spindle). Under these conditions, the inventive xanthan gum is able to obtain full hydration in about 0.7 hour, in about 0.8 hour, in about 0.9 hour, in about 1.0 hour, in about 1.1 hour, in about 1.2 hour, or in about 1.3 hour of propeller mixing at 1800 rpm under ambient conditions in a 10 wt % ammonium nitrate solution at a 0.2 wt % concentration of xanthan gum.
To demonstrate the superior thickening properties of the inventive xanthan gum, solution viscosities utilizing the inventive xanthan gum under varying salt concentrations were compared with conventional xanthan gum. As shown in
As shown in
All of the above noted properties make it possible to incorporate the xanthan gum according to this disclosure as a thickener, viscosity modifier, emulsifier and/or stabilizer into formulations for paper, construction, textiles, food, cosmetics, agrochemical, pharmaceutical, industrial, household cleaning, drilling for and assisted recovery of petroleum, and water treatment. Xanthan gum is used as a component in a number of products to improve properties. The properties may include viscosity, suspension of particulates, mouth feel, bulk, water-binding, thickening, emulsion stabilizing, foam enhancing, and sheer-thinning. Food products using the inventive xanthan gum include, by way of example, salad dressings, syrups, juice drinks, and frozen desserts. Other products also include printing dyes, oil drilling fluids, ceramic glazes, and pharmaceutical compositions, cleaning liquids, paint and ink, wallpaper adhesives, pesticides, toothpastes, and enzyme and cell immobilizers. For pharmaceutical compositions, xanthan gum can be used as a carrier or as a controlled release matrix.
The xanthan gum is produced using conventional submerged Xanthomonas fermentation processes. In one aspect of the disclosure, Xanthomonas seed cultures may be produced in small scale using fermentation vessels from about 0.2 m3 to about 20 m3 over a period of about 20 to about 40 hours. The fermentations may be conducted under ambient conditions. Xanthomonas seed culture may be added to a full scale fermentation vessel of about 20 m3 to about 250 m3 along with a fermentation medium containing about 2.0 to about 6.0 wt % (preferably about 3.0 to about 4.0 wt %) carbon source in the form of corn starch, about 0.1 to about 0.5 wt % (preferably about 0.1 to about 0.3 wt %) nitrogen source in the form of soy protein, and about 0.005 to about 0.02 wt % (preferably 0.05 to about 0.015 wt %) calcium carbonate. Agitation and aeration may be provided during the fermentation to provide for oxygenation of the fermentation medium. The pH of the fermentation medium may be controlled in the range of about 6.0 to about 7.5 with the titrated addition of KOH or NaOH. After about 50 to about 100 hours, the fermentation is complete, resulting in a fermentation beer comprising an aqueous xanthan gum solution.
After fermentation is complete, the xanthan gum can be precipitated from the fermentation beer generally using an organic solvent that is miscible or at least somewhat miscible with water, for example, using an alcohol, a ketone or any other organic solvent that is miscible with water. The organic solvent conveniently may be used in any commercially available form, e.g., as an anhydrous solvent, as a mixture of alcohols or ketones (e.g., isomeric mixtures) or as a mixture of the organic solvent in water (e.g., azeotropic mixtures). In one aspect, the organic solvent can be an alcohol, such as methanol, ethanol, n-propanol, isopropanol (isopropyl alcohol), n-butanol, isobutanol, and the like, including any mixture or combination of alcohols. Further, the alcohol may be ethanol or isopropanol or a combination of ethanol or isopropanol. In still another aspect, to precipitate the xanthan gum, the organic solvent may be added to the fermentation beer in a volumetric ratio of at least about 0.5:1, that is, 0.5 volume of organic solvent for each volume of fermentation beer. In one aspect, the organic solvent may be added to the aqueous xanthan gum solution in a volumetric ratio of about 0.6:1 to about 3:1 of organic to beer. For example, ethanol may be added to the aqueous xanthan gum solution in a volumetric ratio of about 0.6:1 to about 3:1 of organic solvent to beer. In another aspect, the xanthan gum may be precipitated from the fermentation beer by adding ethanol in a volumetric ratio of about 1.25:1 to about 2.5:1 of ethanol to beer.
The xanthan gum precipitate may be separated or isolated using conventional techniques, e.g., by decantation. The isolated xanthan gum may be further treated as desired, for example, to remove excess solvent and/or improve the granularity of the xanthan gum product. In one aspect, the recovered xanthan gum may be pressed to remove excess alcohol and water and then dried. In a further aspect, the drying can be effected at a temperature of about 50° C. to about 90° C. until the residual moisture content is reduced to the desired level, for example, from about 5 to about 15 wt %. Moreover, if desired, the xanthan gum may be milled to an average particle size of about 50 to about 750 microns, for example.
It is considered to be within the ordinary skill of one in the art to subject the isolated xanthan gum product, as described herein, to any conventional post-fermentation/post-isolation treatment, as desired. However, the xanthan gum disclosed herein needs no post-fermentation or post-isolation treatment to obtain the desired properties as disclosed herein.
The test methods utilized herein to characterize the unique features of the xanthan gum according to this disclosure are as follows.
LSRV for xanthan gum was determined using the following procedure. Xanthan gum (0.75 gm—weighed to the nearest 0.01 gm) was slowly added to 299 ml of standard tap water contained in a 400 ml tall form beaker while stirring at 800±20 rpm. Stirring was continued for approximately 4 hours. Just before removing the test solution from stirring (after 4 hours), the solution temperature was adjusted to 25±2° C. The test solution was removed from the stirrer and allowed to sit undisturbed at room temperature for 30±5 minutes (may be placed in a temperature-controlled water bath). After the solution sat for 30 minutes, the temperature was measured by inserting a thermometer into the solution between the center and the side of the beaker. For accuracy, the solution was not disturbed prior to measuring the viscosity. The viscosity at 25±2° C. was measured using a Brookfield Model LV Viscometer, No. 1 spindle at 3 rpm. The viscosity in millipascal second (“mPa·s”) or centipoises (“cP”) was recorded after allowing the spindle to rotate for 3 minutes.
Sea water solution was prepared according to ASTM D1141-52 by dissolving 41.95 g of sea salt, from Lake Products Co., Inc., Maryland Heights, Mo. in 1 liter deionized water. A 300 ml portion of sea water solution was transferred to a mixing cup that was attached to a Hamilton-Beach 936-2 mixer (Hamilton-Beach Div., Washington, D.C.). The mixer speed control was set to low and a single fluted disk was attached to the mixing shaft. At the low speed setting, the mixer shaft rotated at approximately 4,000-6,000 rpm. A 0.86 g portion of xanthan gum was slowly added over 15-30 seconds to the mixing cup and allowed to mix for 5 minutes. The mixer speed control was set to high (11,000±1,000 rpm) and the test solution was allowed to mix for approximately 5 minutes. The mixture was allowed to mix for a total of 45 minutes, starting from time of xanthan gum addition. At the end of the 45 minutes mixing time, 2-3 drops of BARA-DEFOAM® defoaming agent (NL Baroid/NL Industries, Inc., Houston, Tex.) was added and stirring was continued for an additional 30 seconds. The mixing cup was removed from the mixer and immersed in chilled water to lower the fluid's temperature to 25° C.±0.5° C. In order to insure a homogeneous solution, the solution was re-mixed after cooling for 5 seconds at 11,000±1,000 rpm. The solution was transferred from the mixing cup to 400 ml Pyrex beaker and Fann viscosity (Fann Viscometer, Model 35A) was measured. This was accomplished by mixing at 3 rpm. The reading was allowed to stabilize and then the shear stress value was read from dial and recorded as the Sea Water Viscosity value at 3 rpm.
A Hydration Rate tester was developed to measure the Hydration Rate of xanthan gum in an aqueous solution. Hydration Rate is defined as the amount of time for the sample to reach 90% of maximum torque. While this does not directly measure full hydration, the 90% point is a useful metric for sample comparison. The 100% point obtained is more variable since the approach to the final value is gradual and is affected by even small amounts of random error in the measurement. The instrument as shown in
Equipment for determination of Hydration Rate is shown in
1. Test Frame (704)—the body of the instrument securing the variable speed motor (702), SCR controller (714) and torque load cell (710). The torque load cell mounting plate (712) was designed to be quickly removable and self aligning. The controller (714) has a speed control knob (716) and on/off power switch (718).
2. Torque Load Cell (710) and Signal Conditioner (720)—the torque sensing load cell (710) measured very small forces. The signal conditioner (720) electronically sensed the changes in torque on the load cell (710) and electronically sent this information to the digital multi-voltmeter (722). The signal conditioner (720) has an on/off power switch (718).
3. Motor (702)—a DC variable speed motor (702) and appropriate chuck (706) were used for this tester. The speed range was approximately 0-1200 rpm with a high degree of stability (±5 rpm).
4. Multimeter (722)—digitized the voltage readings from the signal conditioner (720) and sent the information to the computer. Readings were taken at 5 per second to 5 significant digits.
5. H-Bar Stirrer (802)—the H-bar stirrer (802) as shown in
6. Sample cup (804)—a 250 ml stainless steel Griffin beaker (804) was used to hold the solvent. The sample cup (804) is held by a sample cup holder (708), and secured by sample cup positioning screws (724).
7. Tachometer—a digital photo tachometer was used to accurately adjust stirrer (802) speed.
Hydration Rate Procedure: The test used 80 mesh particle size xanthan gum, which was dispersed in polyethylene glycol (PEG) at a weight ratio of 3:1 and hand mixed at room temperature (23±2° C.). Samples to be tested were mixed with the dispersant immediately before the test was started. The solute was varied as noted in the examples and figures below. Standard tap water (STW), one of the solutes, was prepared by dissolving 1.0 g of NaCl and 0.15 g CaCl2.2H2O in 1 liter of deionized water. A volume of 130 ml was used. Xanthan gum was tested at the 1 wt % level, unless noted otherwise. Stirrer speed was 600 rpm. The sample was added over a 4-5 second period of time in a very controlled and constant fashion. For consistency and accuracy, the sample must not be added too fast or slow or in an uneven manner.
The data were scaled from 0 to 100% of the maximum torque that occurred during the test. The time to reach 90% of maximum torque was taken as the Hydration Rate. This value was found to be stable and repeatable. The time to reach 100% was not used because the final approach to 100% torque was gradual and subjected to extraneous factors such as electrical noise and or vibration. An example of a torque curve generated in this manner is provided in
In the following examples, the organism used in the fermentations was an Asian strain of Xanthomonas campestris pathovar campestris, which was deposited with the American Type Culture Collection (ATCC, Patent Depository, 1081 University Boulevard, Manassas, Va. 20110-2209, United States of America) on Aug. 31, 2010 under the Accession No. PTA-11272.
The fermentations were conducted under ambient conditions. Xanthomonas seed culture was added to a fermentation vessel along with a fermentation medium containing 3.8 wt % carbon source (corn starch) and 0.25 wt % nitrogen source (soy protein) and 0.01 wt % CaCO3. Agitation and aeration were provided at conventional rates during the fermentation to provide for adequate oxygenation of the fermentation medium. The pH of the fermentation medium was controlled during fermentation in the range of about 6.0 to 7.5 with addition of KOH. After about 60 hours, the fermentation was complete and the xanthan gum was precipitated from the fermentation beer by adding 1.5 volumes of ethanol to the fermentation beer. The recovered xanthan gum was pressed to remove excess alcohol and water and then dried at a temperature of 70° C. until the residual moisture content was 10 wt %. Finally, the xanthan gum was milled to an average particle size of 80 microns.
In each of the examples as shown in
In another example,
Unless indicated otherwise, when a range of any type is disclosed or claimed, it is intended that the recited range is inclusive of the upper and lower limits of the range. Therefore, the terms “between” or “in a range” and similar terms are intended to mean from the lower limit of the range to the upper limit of the range, inclusive. Moreover, and unless indicated otherwise, when a range of any type is disclosed or claimed, for example a range of concentrations, viscosities or temperatures and the like, it is intended to disclose or claim individually each possible number that such a range could reasonably encompass, including any sub-ranges encompassed therein. For example, when describing a viscosity of between about 2400 mPa·s and about 2600 mPa·s, it is intended that each possible number that such a range could reasonably encompass is included in this disclosure, usually to values within the range with one significant digit more than is present in the end points of a range. In this example, by disclosing a viscosity from about 2400 mPa·s to about 2600 mPa·s, such disclosure is intended to be equivalent to disclosing a viscosity of about 2400 mPa·s, about 2410 mPa·s, about 2420 mPa·s, about 2430 mPa·s, about 2440 mPa·s, about 2450 mPa·s, about 2460 mPa·s, about 2470 mPa·s, about 2480 mPa·s, about 2490 mPa·s, about 2500 mPa·s, about 2510 mPa·s, about 2520 mPa·s, about 2530 mPa·s, about 2540 mPa·s, about 2550 mPa·s, about 2560 mPa·s, about 2570 mPa·s, about 2580 mPa·s, about 2590 mPa·s, or about 2600 mPa·s, including any ranges, subranges, or any combinations of ranges or subranges between these recited numbers, inclusive. Accordingly, Applicants reserve the right to proviso out or exclude any individual members of any such group, including any sub-ranges or combinations of sub-ranges within the group, if for any reason Applicants choose to claim less than the full measure of the disclosure, for example, to account for a reference that Applicants are unaware of at the time of the filing of the application.
In any application before the United States Patent and Trademark Office, the Abstract of this application is provided for the purpose of satisfying the requirements of 37 C.F.R. §1.72 and the purpose stated in 37 C.F.R. §1.72(b) “to enable the United States Patent and Trademark Office and the public generally to determine quickly from a cursory inspection the nature and gist of the technical disclosure.” Therefore, the Abstract of this application is not intended to be used to construe the scope of the claims or to limit the scope of the subject matter that is disclosed herein. Moreover, any headings that may be employed herein are also not intended to be used to construe the scope of the claims or to limit the scope of the subject matter that is disclosed herein. Any use of the past tense to describe an example otherwise indicated as constructive or prophetic is not intended to reflect that the constructive or prophetic example has actually been carried out.
This patent application claims priority benefit of U.S. Provisional Application Nos. 61/378,612, filed Aug. 31, 2010; 61/378,988, filed Sep. 1, 2010; and 61/383,795, filed Sep. 17, 2010, each of which is incorporated herein by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| 61378612 | Aug 2010 | US | |
| 61378988 | Sep 2010 | US | |
| 61383795 | Sep 2010 | US |
