PASSIVE THERMALLY STABILIZING CONTAINER ASSEMBLY

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims priority to and the benefit of Provisional U.S. Patent Application serial number 60/725,463 filed on October 11, 2005, and Provisional U.S. Patent Application serial number 60/760,487 filed on January 20, 2006.

TECHNICAL FIELD

[0002] Certain embodiments of the present invention relate to thermally stabilizing containers (e.g., a cooling container or a warming container). More particularly, certain embodiments of the present invention relate to a nested, passive thermally stabilizing container assembly which uses a thermal disk (e.g., a cold disk or a heat disk) for keeping food thermally stabilized (e.g., cool or warm) within the container assembly.

BACKGROUND OF THE INVENTION

[0003] Various types of food containers exist which attempt to keep food cool and/or warm in various ways. For example, U.S. Patent No. 5,701,757 describes a portable food refrigeration system. The system includes an outer pan constructed from a rigid insulating material and including at least one handle secured to the upper exterior portion. The system also includes a gel pack removably positioned on the interior bottom surface and which is freezable. The system further includes an inner pan formed to a shape similar to the outer pan for retaining food an including at least one handle secured to the upper exterior portion. The inner pan is slidably positionable within the interior of the outer pan to produce a nested relationship between the inner and outer pans. One of the

pans has a sealing protrusion located substantially adjacent to and along the upper edge of the one pan. The other pan has a scaling groove located substantially adjacent to and along the upper edge of the other pan such that, when the pans are placed in a nested relationship, the scaling groove and the sealing protrusion are moved into a mated condition. The mated condition of the sealing protrusion and the sealing groove forms a substantially air tight barrier and resists movement of the inner pan out of the nested relationship with the outer pan.

[0004] U.S. Patent No. 5,579,946 describes a food container including a bowl having a double-wall structure, including an interior wall made of metal material and an exterior wall made of plastic material. The interior wall defines an interior chamber and has a bottom wall portion and a sidewall portion. The sidewall portion is integrally formed with and extends upwardly from the bottom wall portion and has a tapered upper lip. The exterior wall has a bottom wall portion and a sidewall portion. The sidewall portion is integrally formed with and extends upward from the bottom wall portion and has an upper rim. The exterior and interior walls are positioned substantially parallel to each other and are spaced apart. The tapered upper lip of the interior wall is air-tightly connected to the upper rim of the exterior wall, thereby forming a top edge of the bowl and a sealed chamber between the interior and exterior walls. A lid is sized to span the top edge of the bowl for covering the interior chamber of the bowl. The lid has a double-wall structure including a bottom wall made of metal material and a top wall made of plastic material. The top and bottom walls of the lid each have a circumferential edge. The top and bottom walls are positioned in a substantially parallel and spaced apart relationship. The circumferential edge of the top wall is air-tightly connected to the circumferential edge of the bottom wall, thereby forming a sealed chamber between the top and bottom walls. The interior wall of the bowl and the bottom wall of the lid are polished for substantially reducing and preventing heat radiation. The sealed chamber of the bowl and the sealed chamber of the lid substantially reduce and prevent heat conduction. The tapered upper

lip of the interior wall of the bowl substantially reduces and prevents heat convection. The container is able to keep food warm for an extended period of time.

[0005] U.S. Patent No. 6,434,970 describes a plate comprising a substantially curved surface having a recess formed in the center of the surface. A reusable cold disk is provided in the recess. A removable cover is also provided to form an empty space between the cover made of a cylindrical main body with a closed top and an open bottom, and the surface of the plate. The top of the cover is provided with a depression in which a reusable cold disk is placed.

[0006] U.S. Patent No. Re. 35,437 describes a container for milk and cereal comprising a milk reservoir having an opening and a resealable fluid-tight cap means removably secured over the opening. There is at least one freeze pack adjacent to the milk reservoir and filled with a freezable substance, and a cereal compartment adjacent to the milk reservoir and having an opening and a cover removably secured over the cereal compartment opening. At least one valve is interposed between the milk reservoir and the cereal compartment. The valve has a closed positioned for keeping the milk and cereal separate and an open position for allowing the milk to enter the cereal compartment.

[0007] Further limitations and disadvantages of conventional, traditional, and proposed approaches will become apparent to one of skill in the art, through comparison of such systems and methods with the present invention as set forth in the remainder of the present application with reference to the drawings.

BRIEF SUMMARY OF THE INVENTION

[0008] An embodiment of the present invention comprises a container assembly. The container assembly includes a thermally-insulating outer shell and a thermally-conductive inner shell configured to nest within the outer shell. The inner shell has a recessed

volume at a bottom portion of the inner shell. The container assembly further includes a removable thermal disk configured to rest within the recessed volume of the inner shell. The thermal disk comprises a chillablc, freezable, heatable, or activatable material. The container assembly also includes a removable food container configured to nest within the inner shell.

[0009] Another embodiment of the present invention comprises a method of assembling a container. The method includes nesting a thermally-conductive inner shell into a thermally-insulating outer shell. The method further includes placing a removable thermal disk into a recessed volume at a bottom portion of the inner shell. The method also includes nesting a removable food container into the inner shell over the thermal disk.

[0010] A further embodiment of the present invention comprises a method of keeping food thermally stabilized. The method includes chilling, freezing, heating, or activating a removable thermal disk. The method further includes placing the food into a removable food container and chilling or heating the food in the removable food container. The method also includes placing the thermal disk into a recessed volume at a bottom portion of a thermally-conductive inner shell that is nested into a thermally-insulating outer shell. The method further includes nesting the food container, containing the food, into the inner shell.

[0011 ] Yet another embodiment of the present invention comprises a container assembly including an outer, thermally-insulating shell and a thermally-conductive inner shell which is nested into and affixed to the outer shell. The inner shell has a recessed volume at a bottom of the shell. A removable thermal disk is configured to rest, unattached, within the recessed volume of the inner shell. The thermal disk comprises a material, capable of being chilled, frozen, heated, or activated which is permanently encapsulated within a casing made of, for example, metal or plastic. The assembly also comprises a removable food container capable of being nested into the inner shell without forming an

air-tight seal or a liquid-tight seal between the food container and the inner shell. A removable lid which fits onto the food container is also optionally provided. The lid is not a double-walled structure with an insulating air gap or vacuum gap in between.

[0012] These and other advantages and novel features of the present invention, as well as details of an illustrated embodiment thereof, will be more fully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

[0013J Fig. 1 illustrates three exemplary embodiments of a container assembly, in accordance with various aspects of the present invention.

[0014] Fig. 2 illustrates the nested configuration of the first exemplary embodiment of a container of Fig. 1 , in accordance with various aspects of the present invention.

[0015] Fig. 3 illustrates certain features of the first embodiment of Fig. 2, in accordance with various aspects of the present invention.

[0016] Fig. 4 illustrates several exemplary lidded configurations of the first embodiment of Fig. 2, in accordance with various aspects of the present invention.

[0017] Fig. 5 illustrates the nested configuration of the second exemplary embodiment of a container of Fig. 1, in accordance with various aspects of the present invention.

[0018] Fig. 6 illustrates an exemplary un-lidded configuration and two exemplary lidded configurations of the second embodiment of Fig. 5, in accordance with various aspects of the present invention.

[0019] Fig. 7 illustrates the nested configuration of the third exemplary embodiment of a container of Fig. 1, in accordance with various aspects of the present invention.

[0020] Fig. 8 illustrates an exemplary un-lidded configuration and an exemplary lidded configuration of the third embodiment of Fig. 7, in accordance with various aspects of the present invention.

[0021] Fig. 9 is a flow chart of an embodiment of a method of assembling any of the various container assembly embodiments shown in Figs. 1 -8, in accordance with various aspects of the present invention.

[0022] Fig. 10 is a flow chart of an embodiment of a method of keeping food thermally stabilized using any of the various container assembly embodiments shown in Figs. 1-8, in accordance with various aspects of the present invention.

[0023] Fig. 11 is an exemplary graph illustrating the cold-prcscrving capability of the embodiment of Fig. 5 without a lid, in accordance with various aspects of the present invention.

[0024] Fig. 12 is an exemplary graph of Fig. 11 with the additional cold-preserving capability shown when a lid is provided, in accordance with various aspects of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0025] Fig. 1 illustrates three exemplary embodiments of a passive thermally-stabilizing container assembly, in accordance with various aspects of the present invention. As used herein, the term "passive" means that the container does not include any active electrical components to provide cooling or heating. As used herein, the term "thermally- stabilizing" means "keeping within a temperature range over a period of time". A first embodiment 100 is configured as a deep bowl. A second embodiment 200 is configured as a shallow dish or platter, and a third embodiment 300 is configured as a sectioned dish or platter. The bowl 100 may be used, for example, for keeping potato salad cool, or for

keeping a potato casserole warm. The platter 200 may be used, for example, for keeping applesauce cool, or for keeping spaghetti warm. The sectioned platter 300 may be used, for example, for keeping a variety of cut vegetables cool and separated, or for keeping a variety of finger foods warm and separated. All three container assembly embodiments are very similar in construction as will be described herein.

[0026] Fig. 2 illustrates the nested configuration of the first exemplary embodiment 100 of a container assembly of Fig. 1, in accordance with various aspects of the present invention. The assembly 100 includes a thermally-insulating outer shell 110 and a thermally-conductive inner shell 120 nested into and permanently or removably attached to the outer shell 110. As used herein, the phrase "nested into" means "put snugly together inside of. As used herein, the term "thermally-insulating" means "substantially preventing the conduction of thermal energy". As used herein, the term ''thermally- conductive" means "substantially facilitating the conduction of thermal energy". Therefore, the thermally-insulating outer shell is an outer shell that substantially prevents the conduction of thermal energy therethrough, and the thermally-conductive inner shell is an inner shell that substantially facilitates the conduction of thermal energy therethrough.

[0027] Permanent attachment of the inner shell 120 to the outer shell 110 may be accomplished by means of an adhesive, for example, or some other permanent fastening means. Removably attached, as used herein, may mean that the inner shell 120 is simply resting within the outer shell 1 10 due to the force of gravity. Alternatively, removably attached may mean that there is a means for fastening the inner shell 120 within the outer shell 110 such that the inner shell 120 may be easily de-fastened from the outer shell 110 (e.g., via a snap-on means).

[0028] There may be at least one layer or volume of air (or some other gas), for example, between at least a portion of the inner shell 120 and at least a portion of the outer shell 110 for insulating purposes. Alternatively, there may be at least one vacuum gap between

at least a portion of the inner shell 120 and at least a portion of the outer shell 110 for insulating purposes. Some other insulating material (e.g., an insulating foam material) may be configured between the outer shell 110 and the inner shell 120 instead, in accordance with an alternative embodiment of the present invention. The outer shell 110 may comprise a thermally-insulating plastic material, for example, and the inner shell 120 may comprise a thermally- conductive metal such as aluminum, for example. The outer shell 1 10 may be at least partially transparent or may be opaque, having at least one color, for example.

[0029] The inner shell 120 includes a recessed volume 125 (see Fig. 3) configured to accept a thermal disk 130. The thermal disk 130 may be chilled, frozen, heated, or activated, in accordance with various embodiments of the present invention. The recessed volume is substantially centered within the bottom of the inner shell 120, in accordance with an embodiment of the present invention. The thermal disk 130 may comprise, for example, frozen or heated water permanently encapsulated in a disk-shaped plastic, a soft gel pack permanently fitted into an aluminum material casing, for example, or any liquid (e.g., an alcohol-based liquid), solid, or semi-solid material that may be chilled, frozen, heated, or activated to give off or to cool down. In accordance with an alternative embodiment of the present invention, the thermal disk 130 does not include any encapsulating casing but, instead, comprises only the chillable, freezable, heatable, or activatable material (e.g., ice formed in an ice tray which is substantially in the shape of the recessed volume).

[0030J Even though the term disk is used herein, the shape of the thermal disk 130 may be any convenient shape for fitting into the recessed volume 125 of the inner shell 120. The thermal disk 130 fits into and rests within the recessed volume 125 such that the thermal disk 130 makes thermally-conductive contact with the inner shell 120. As a result, cold or heat is conducted up the walls of the metal (e.g., aluminum) inner shell 120. The thermal disk 130 is easily removable from the inner shell 120 cither by tipping

the inner shell 120 (and connected outer shell 110) upside down, or by using ones fingers to insert into notches in the sides or top of the thermal disk 130 and pulling the thermal disk out of the recessed volume. As an alternative, the notches may be in the inner shell 120 adjacent to the thermal disk 130. As a result, the thermal disk 130 may be removed from the assembly 100 and placed in, for example, a freezer for freezing or an oven for heating. Alternatively, the thermal disk may comprise a disposable chemical pack that, when activated, gives off heat or cools down. The disposable chemical pack is a consumable product that may be thrown away once the pack has been exhausted.

[0031] Chemical packs may be activated in various ways. For example, some chemical packs are activated by shaking or squeezing. Other chemical packs are activated by allowing oxygen to react with the chemical substance within the pack. A chemical reaction allows heat to be given off (heating) or heat to be absorbed (cooling).

[0032] The assembly 100 further includes a removable inner bowl or food container 140 made out of, for example, a stainless steel material for holding food. The bowl 140 is configured to fit into the inner shell 120 in a nested manner without forming a seal between the bowl 140 and the inner shell 120. As a result, the food is kept cool or warm by at least the thermally conductive inner shell 120 which is in thermal contact with the thermal disk 130. It is desirable to cool or warm the food to a desired temperature (e.g., in a refrigerator or oven) before placing the food in the assembly 100. The desired temperature may be a temperature at which the food is to be served, or may be a temperature somewhat cooler or warmer than that.

[0033] As an option, the assembly 100 further includes a removable lid (e.g., a plastic lid) 150 which fits over top of the bowl 140 and may be snapped onto the bowl 140. The lid may be a thermally-insulating lid. However, the lid may not be a double-walled structure with an insulating air-gap or vacuum gap in between. Instead, the lid may be a single, solid thermally-insulating material (e.g., plastic), in accordance with an embodiment of the present invention. The overall dimensions of the container assembly 100 may range

from being very deep and bowl-shaped to being very flat and shallow, such as described in the second and third embodiments herein. In general, any shape may be accommodated (e.g., round and deep, or rectangular and flat).

[0034] In a typical configuration, the removable food container 140 includes a rim 145 circumscribing an upper edge of the food container 140. The lid 150 is capable of being snapped onto the rim 145 to enclose any food which is placed within the food container 140. In accordance with an embodiment of the present invention, the lid 150 is at least partially transparent in order to see any food inside the food container 140. In accordance with another embodiment of the present invention, the lid 150 is opaque.

[0035] Therefore, in accordance with various embodiments of the present invention, the nested configuration 100 with the thermal disk 130 provides an environment in which food may stay thermally stabilized (i.e., cold or warm) longer. The assembly 100 is a passive thermally-stabilizing container assembly. That is, there are no active components requiring power to keep the food thermally stabilized. The thermal disk, the insulating materials, and the thermally conductive materials in the nested configuration provide the ability to keep the food thermally stabilized for a longer period of time.

[0036] Fig. 3 illustrates certain features of the first embodiment 100 of Fig. 2, in accordance with various aspects of the present invention. As can be seen in Fig. 3, the thermal disk 130 may be removed from the recessed volume 125 of the inner shell 120. Also, the food container 140 may be removed from the inner shell 120. The outer shell 110 is permanently or removably attached to the inner shell 120. In accordance with an embodiment of the present invention, there are no handles attached to or integrated into any portion of the container assembly.

[0037] Fig. 4 illustrates several exemplary lidded configurations of the first embodiment of Fig. 2, in accordance with various aspects of the present invention. The lid 150 may be

very shallow or significantly concave, for example. The lid 150 may be snapped onto the food container 140, and then subsequently removed.

[0038] Fig. 5 illustrates the nested configuration of the second exemplary embodiment 200 of a container of Fig. 1 , in accordance with various aspects of the present invention. The second embodiment 200 is similar in construction to the first embodiment 100 except that the second embodiment 200 is of a much shallower and flatter shape, constituting a platter-like or plate-like container assembly 200. The container assembly 200 comprises an outer insulating shell 210 (e.g., an insulating plastic shell) which is attached to an inner thermally conductive shell 220 (e.g., an aluminum shell that fits, in a nested manner, within the plastic shell 210 and is permanently or removably attached thereto). There may be an insulating layer of air, for example, or a vacuum between the outer plastic shell 210 and the inner shell 220. Some other insulating material may be configured between the outer shell 210 and the inner shell 220 instead, in accordance with an alternative embodiment of the present invention.

[0039] The inner shell 220 includes a recessed volume to accept a thermal disk 230. Again, the thermal disk 230 may comprise, for example, frozen or heated water permanently encapsulated in a disk-shaped plastic, a soft gel pack permanently fitted into an aluminum casing, for example, or any other encapsulated material that may be chilled, frozen, heated, or activated. The thermal disk 230 fits into and rests within the recessed volume such that the thermal disk 230 makes thermally conductive contact with the inner shell 220. As a result, cold or heat is conducted up the walls of the inner aluminum shell 220. The thermal disk 230 is easily removable from the inner shell 220 either by tipping the inner shell 220 (and connected outer shell 210) upside down, or by using ones fingers to insert into notches in the sides or top of the thermal disk 230 and pulling the thermal disk out of the recessed volume. Again, the notches may be in the inner shell 220 adjacent to the thermal disk 230. As a result, the thermal disk 230 may be removed from the assembly 200 and placed in a freezer for freezing or an oven for heating, for example.

[0040] The assembly 200 further includes a removable inner platter or food container 240 made out of, for example, stainless steel for holding food. The platter 240 fits into the inner shell 220 in a nested manner without forming a seal between the platter 240 and the inner shell 220. As a result, the food is kept cool or warm by at least the thermally conductive inner shell 220 which is in thermal contact with the thermal disk 230. It is desirable to cool or warm the food to a desired temperature (e.g., in a refrigerator or oven) before placing the food in the assembly 200.

[0041] Fig. 6 illustrates an exemplary un-lidded configuration and two exemplary lidded configurations of the second embodiment 200 of Fig. 5, in accordance with various aspects of the present invention. The assembly 200 further includes a removable insulating lid (e.g., plastic lid) 250 which fits over top of the platter 240 and snaps onto the platter 240. The lid may not be a double-walled structure with an insulating air-gap or vacuum gap in between. Again, the lid 250 may be relatively flat or more concave in shape.

[0042] Fig. 7 illustrates the nested configuration of the third exemplary embodiment 300 of a container of Fig. 1, in accordance with various aspects of the present invention. The third embodiment 300 is essentially the same as the second embodiment 200 (and very similar to the first embodiment 100) except that the platter 240 is replaced with a removable sectioned or compartmentalized vegetable plate 340 to form the container assembly 300. The plate 340 includes dividers or walls 341 to allow, for example, vegetables or other food items to be kept separated from each other within the plate 340. Again, the container assembly 300 may further include a removable insulating (e.g., plastic) lid 250 that fits over top of the plate 340 and snaps onto the plate 340. Again, the lid 250 may not be a double-walled structure with an insulating air-gap or vacuum in between the walls. Also, there are no handles designed into the assembly 300.

[0043] Fig. 8 illustrates an exemplary un-lidded configuration and an exemplary lidded configuration of the third embodiment 300 of Fig. 7, in accordance with various aspects

of the present invention. In accordance with various embodiments of the present invention, the outer insulating shells 1 10 and 210 may comprise a colored, transparent plastic (e.g., a blue transparent plastic) such that the respective inner metal shells 120 and 220 may be observed through the shells 1 10 and 210. Such a feature provides a desirable aesthetic look to the container assembly.

[0044] Fig. 9 is a flow chart of an embodiment of a method 900 of assembling any of the various container assembly embodiments shown in Figs. 1-8, in accordance with various aspects of the present invention. Tn step 910, a thermally-conductive inner shell is nested into a thermally-insulating outer shell. In step 920, a removable thermal disk is placed into a recessed volume at a bottom portion of the inner shell. In step 930, a removable food container is nested into the inner shell over the thermal disk. In step 940, a removable lid is snapped onto the removable food container, wherein the lid is not a double-walled structure with an insulating air gap or a vacuum gap therebetween (i.e., between the two walls of the double- walled structure).

[0045] Fig. 10 is a flow chart of an embodiment of a method 1000 of keeping food thermally stabilized using any of the various container assembly embodiments shown in Figs. 1-8, in accordance with various aspects of the present invention. In step 1010, a removable thermal disk is chilled (reduced in temperature, e.g., in a freezer) or frozen (reduced in temperature to at least the point where a liquid material or gel material within the cold disk transitions to a solid material state), heated (increased in temperature, e.g., in a oven), or activated (e.g., shaken or squeezed). In step 1020, food is placed into a removable food container and the food is chilled or heated in the removable food container (e.g., in a refrigerator or oven). In step 1030, the thermal disk is placed into a recessed volume at a bottom portion of a thermally-conductive inner shell that is nested into a thermally-insulating outer shell. In step 1040, the food container, containing the food, is nested into the inner shell. In step 1050, a removable lid is snapped onto the

removable food container, wherein the lid is not a double-walled structure with an insulating air gap or vacuum gap therebetween.

[0046] In accordance with various alternative embodiments of the present invention, the food could be chilled or heated by itself (e.g., in a refrigerator or oven), without being in the removable food container when being chilled or heated. The food container may or may not be separately chilled or heated. Also, the inner shell (with or without the outer shell) could be chilled or heated before assembling the container assembly for use. Furthermore, the nested combination of the outer shell, the inner shell, and the food container could be chilled or heated before placing the thermal disk in the recessed volume of the inner shell and before placing food in the food container. Other methods of pre-chilling or pre-heating various elements of the container assembly may be possible as well.

[0047J Fig. 11 is a graph 1 100 illustrating the cool-preserving capability of the embodiment 200 of Fig. 5 without a lid, in accordance with various aspects of the present invention. Two amounts of applesauce (80 oz. each) were pre-chilled to about 43 degrees F (point 1101) and placed in two separate food containers 240 of the assembly 200. The applesauce in the containers was about 1 inch deep. The first food container 240 served as a control and was left out to sit on a glass table, without a lid, over a period of time at ambient temperature (about 76 to 79 degrees F), (see plot 1110). The second food container 240 was nested into the inner shell 220 (which is attached to the insulating outer shell 210) with a pre-frozen thermal disk in the recessed volume of the inner shell, in accordance with an embodiment of the present invention. The second food container 240 was left out to sit on a glass table, also without a lid, over the same period of time at the same ambient temperature (see plot 1110) as the first food container 240. Temperature measurements were taken at three different points within the applesauce for the first food container (plots 1121-1123) and the second food container (plots 1131-1133).

[0048] Temperatures at a first point "B" (plots 1121 and 1 131) were measured about a half inch down within the applesauce over the thermal disk. Temperatures at a second point "F" (plots 1122 and 1132) were measured about a half inch down within the applesauce about halfway between the center of the food container 240 and the rim of the food container 240. Temperatures at a third point "H" (plots 1123 and 1133) were measured near the rim of the food container 240 about a half inch down within the applesauce.

[0049] As can be seen from the graph 1100, a significant temperature gap 1140 develops between the applesauce in the first food container and the applesauce in the second food container of the present invention. The temperature gap 1140 illustrates the cool- preserving capability of the assembly 200 when in the nested configuration with the thermal disk 230 compared to not being in the nested configuration with the thermal disk. Again, neither the first nor the second food containers 240 had a lid during these measurements.

[0050] Fig. 12 is the graph 1100 of Fig. 11 with the additional cool-preserving capability (plot 1150) shown when a lid is provided, in accordance with various aspects of the present invention. The point "F" was measured for temperature over time once again. The ambient temperature (plot 1111) was a couple of degrees higher during these measurements than during the previous measurements, however, and the starting prc- chilled temperature 1102 of the applesauce was about 41 degrees F instead of 43 degrees F as before. Ignoring these differences, having the lid allowed the temperature at point "F" to remain about 6 degrees cooler (e.g., sec point 1151) over time than without the lid (e.g., sec point 1152). Also, having the lid and the thermal disk in the nested configuration allows the temperature at point "F" to remain about 15 degrees cooler (e.g., see point 1151) after more than two hours compared to having the food sitting in an open bowl with no thermal disk or nested configuration (see point 1153).

[0051] In summary, embodiments of the present invention provide a passive thermally- stabilizing container assembly comprising a nested structure of an outer shell, an inner shell, a thermal disk, a food container, and, optionally, a lid which allows food to remain cooler or warmer longer.

[0052] While the invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. 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. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.