Patent Publication Number: US-2010128433-A1

Title: Cap for Electronics Enclosure

Description:
BACKGROUND OF THE INVENTION 
     In the telecommunications and electrical transmission industry, there are various different types of enclosures for housing and protecting electronic equipment such as switches, connectors and/or splices. The enclosed electronic equipment may be in communication with data transmission lines or cables that can be directed into the enclosure. In some instances, these enclosures are designed for placement outdoors. Such outdoor enclosures must protect the electronic equipment from environmental concerns such as precipitation as well as from tampering by humans and/or animals. 
     The electronics equipment housed in outdoor enclosures often produces its own heat. Accordingly, the enclosures used with such heat-producing equipment should be designed to remove this heat to keep the enclosed equipment within safe operating temperatures. One way in which this may be accomplished is by including vents on the enclosure that vent the heat to the surrounding environment. The vents are typically located near the top of the enclosure so that heated air rising within the enclosure will exhaust through the vents. 
     Locating the enclosure outdoors may also expose the top of the pedestal to solar radiation such as sunlight which may harmfully raise the temperature of the enclosure. Accordingly, it would be advantageous to have a pedestal style enclosure that provides venting of the enclosure interior while resisting harmful temperature increases due to solar radiation. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention provides an electronics enclosure that may be in the form of a pedestal style enclosure and that may include a cap designed to help prevent excessive heat from building-up in the enclosure. The cap, which is installed on the top of the pedestal, can be a hollow structure that includes an internal void or air chamber. In particular, the cap can include an upper shield plate that is joined to a lower guide plate so that an air gap is formed between the two plates. When installed on an enclosure, the upper shield plate will be exposed on the top of the enclosure while the lower guide plate is exposed to the interior. If the enclosure is located outdoors, solar radiation may impinge upon the upper shield plate of the cap tending to raise the temperature of the enclosure. The air gap provided between the upper shield plate and the lower guide plate may act as an additional buffer helping to prevent the solar-induced heat from being transferred to the interior of the enclosure. 
     In addition, the guide plate of the cap may be shaped or contoured to improve the venting of heat from the interior of the enclosure. The cap can be installed on the top of a pedestal style enclosure so that the guide plate is exposed to the interior. To provide the vents, the cap can include one or more vent panels that are offset or spaced apart from the wall of the pedestal housing on which the cap is installed. The lower guide plate may be contoured to have a drooping center point protruding towards the interior of the enclosure and to have arch-like lobes curving upwardly and outwardly toward the vent panels. As the enclosed electronics heat the air in the interior of the enclosure, the heated air can rise inside the pedestal housing and encounter the guide plate where the contours direct the heated air to the vents formed by the offset vent panels. 
     The cap can be made from molded thermoplastic material. Preferably, the cap can be made as a single, monolithic part by a blow molding process. In this process, a blank or preform of thermoplastic material is placed between two opposing mold walls. Pressurized air may be injected into the blank causing the blank to inflate against the opposing mold walls and assume the shape of the mold walls. The resulting part is the hollow cap with an internal air gap between the upper and lower plates. Further, one of the mold walls may correspond to the contoured guide plate so as to accordingly shape the inflated blank. 
     A possible advantage of the disclosed enclosure cap is that the air gap helps compensate for solar radiation impinging on the enclosure. Another possible advantage is that the contoured shape of the lower guide plate helps direct heated air from the interior toward the vents. These and other advantages and features will become apparent from the accompanying detailed description and the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an exemplary pedestal type electronics enclosure such as commonly used in telecommunications and electrical transmission. 
         FIG. 2  is a cross sectional view taken along line  2 - 2  of  FIG. 1  illustrating the interior of the pedestal enclosure with an exemplary enclosure cap installed on the top end of the pedestal enclosure. 
         FIG. 3  is a top perspective view of the enclosure cap removed from the main housing of the enclosure illustrating the upper shield plate. 
         FIG. 4  is a bottom perspective view of the enclosure cap illustrating the contoured lowered guide plate. 
         FIG. 5  is a perspective assembly view of the hollow enclosure cap illustrating the upper shield plate removed from the lower guide plate. 
         FIG. 6  is a top plane view of the enclosure cap taken primarily of the upper shield plate. 
         FIG. 7  is a cross-sectional view taken along line  6 - 6  of  FIG. 5  illustrating the air gap formed between the upper shield plate and the lower guide plate of the enclosure cap and particularly illustrating the drooping center point of the lower guide plate. 
         FIG. 8  is a cross-sectional view taken along line  7 - 7  of  FIG. 5  illustrating the air gap formed between the upper shield plate and the lower guide plate of the enclosure cap and particularly illustrating the depending troughs of the lower guide plate. 
         FIG. 9  is a cross-sectional view taken along line  8 - 8  of  FIG. 5  illustrating the air gap formed between the upper shield plate and the lower guide plate and particularly illustrating the joinder of the upper shield plate and lower guide plate. 
         FIG. 10  is a perspective view of another embodiment of a pedestal style electronics enclosure that is cylindrical in shape. 
         FIG. 11  is a cross sectional view taken along line  11 - 11  of  FIG. 10  illustrating the interior of the cylindrical enclosure which includes a circular enclosure cap positioned on the top end of the pedestal enclosure housing. 
         FIG. 12  is a top perspective view of the circular enclosure cap removed from the housing of the enclosure illustrating the dome-like upper shield plate. 
         FIG. 13  is a bottom perspective view of the circular enclosure cap illustrating the contoured shape of the inner guide plate of the cap. 
         FIG. 14  is a top plane view of the circular enclosure cap. 
         FIG. 15  is a perspective assembly view of the circular enclosure cap illustrating an upper shield plate removed from the lower guide plate. 
         FIG. 16  is a cross sectional view taken along line  16 - 16  of  FIG. 14  illustrating an air gap formed between the upper shield plate and the lower guide plate of the circular enclosure cap. 
     
    
    
     DETAILED DESCRIPTION 
     Now referring to the drawings, wherein like reference numbers refer to like elements, there is illustrated in  FIGS. 1 and 2  an exemplary pedestal-style electronics enclosure  100  intended for outdoor service. The enclosure  100  can include a generally upright, mast-like main body or housing  102 . In the illustrated embodiment, the housing  102  can be in the shape of an elongated, open-ended rectangle with a top end  104  and an opposing bottom end  106 . The rectangular housing can have a square cross-section, but in other embodiment can have other suitable shapes including circular. Furthermore, it should be noted that terms such as “top,” “bottom,” “upper,” “lower,” and the like are meant only to provide reference and are not to be construed as a limitation on the claims. The housing  102  can be made from formed sheet metal, molded plastic or any other suitable material. Referring to  FIG. 2 , the interior  108  of the housing  102  is generally open space inside of which various switches, connectors, terminals and other electronic equipment can be located. The bottom end  106  of the housing  102  can provide an opening into which telecommunications lines or cables can be directed. In other embodiments, the lower end  104  can be generally closed with punch-outs or ports through which lines and cables can be directed. 
     In some installations, the bottom end  106  of the housing  100  can be attached to a base that may be partially or completely buried underground. The housing can be located above and rise upwards from the ground. Underground cables or lines can be directed into and through the base and upwards through the opening at the bottom end  106 . The cable or lines can then be directed through the interior  108  to the electronics equipment, the vertical position of which is preferably above ground. Service technicians can access the above-ground electronic equipment by detaching and lifting up the housing  102  from the base, without otherwise having to unbury the base portion of the enclosure. In other embodiments, the pedestal style housing can be set on a concrete pad or floor. 
     A cap  110  is located at the top end  104  of the enclosure housing  102 . In the illustrated embodiment, the cap  110  is a square, generally-box like structure that can be installed over and sit on a rim  109  of the open top end  104 . To match the square cross-section of the housing  102 , the box-like cap  110  can likewise be square and have four interconnected, orthogonally arranged sides  120 . However, in other embodiments, the cap can have other shapes and designs such as rectangular or circular. The cap  110  can give the pedestal enclosure  100  an approximately flattop appearance. 
     To remove the heated air from the interior of the enclosure such as the air that may be heated by the electronic components, the cap  110  can be configured to provide one or more vents. In pedestal-style enclosures, the upright pedestal design can produce a chimney effect in which the heated air inside the enclosure rises up the elongated housing toward the cap and exhausts out the vents. The rise of the heated air can also help draw cooler air from the surrounding environment into the enclosure through a location proximate the bottom end of the housing. The circulating air through the enclosure can help keep the electronic equipment cool. To facilitate the chimney effect, it is desirable to locate the exhaust vents near the top of the enclosure and the intake vents near the bottom end. 
     Referring to  FIGS. 1 and 2 , to form the exhaust vents, the cap  110  can include one or more offset vent panels  112 . In the illustrated embodiment, a rectangular vent panel  112  can protrude from each of the four sides  120  so that the assembled enclosure will have four exhaust vents. The vent panels  112 , which in the illustrated embodiment are rectangular in shape, protrude or bulge outwardly from the sides  120  of the box-like cap  110 . When installed on the enclosure housing, the vent panels are offset with respect to or spaced apart from the uppermost rim  109  of the housing  102  and thus provide a clearance  116  between the vent panel and the housing sidewall. The clearance  116  is in communication with the interior  108  of the enclosure and allows the rising heated air to escape to the surrounding environment. 
     To draw cooler environmental air into the enclosure and facilitate the chimney effect, the lower end  106  of the housing can include one or more open intake vents  118  communicating with the interior  108 . To inhibit rain or other precipitation from entering the enclosure  100  through the vents, the offset vent panels  112  can be arranged so that the clearances  116  are directed generally downwards. Additionally, it is desirable to make the clearances as narrow as possible to prevent insects and other foreign objects from entering the enclosure. Screens or mesh may also be installed in the clearances  116  to prevent foreign objects from entering the enclosure. Additionally, the illustrated intake vents  118  may also be directed downwardly and include screens or mesh. 
     Referring to  FIGS. 3 ,  4  and  5 , and as mentioned above, the enclosure cap  110  can have a generally box-like structure with four orthogonally arranged, interconnected sides  120 . The exterior surface  122  of the cap  110 , which is intended to be exposed to the surrounding environment, may have a smooth, generally dome-like shape while the inner surface  124 , which is intended to be exposed to the interior of the enclosure, may have a contoured shape, the particular details of which will be described below. Additionally, one or more inward projecting bosses  128  may be formed proximate each of the four corners  126  of the cap. As can be appreciated, when the cap is installed on the top end of the housing, the bosses  128  can rest a top the uppermost rim  109  of the housing. 
     Referring to  FIGS. 5 ,  6  and  7 , in accordance with one aspect of the disclosure, the enclosure cap  110  can be formed as a hollow structure having an internal void or air gap  130 , which may assist in moderating the temperature of the enclosure  100 . The internal air gap  130  can be substantially enclosed within and confined by the cap structure. When the cap  110  is installed on the top of an outdoor pedestal enclosure, solar radiation such as sun light can impinge upon the cap. The air gap  130  within the hollow cap  110  may absorb some of the heat associated with the impinging sunlight and can thereby function as a buffer that insulates the heat from the rest of the enclosure. 
     In the illustrated embodiment, the enclosure cap  110  includes an upper shield plate  132  and a lower guide plate  134  that are joined together and in between which is delineated the air gap  130 . As can be appreciated, the upper shield plate corresponds to the dome-like exterior surface  122  in  FIGS. 3 ,  4  and  5 , and the lower guide plate  134  corresponds to the contoured inner surface  124 . In this case, the upper shield plate  132  defines a dome-like structure that includes a generally planar central portion  140  and a depending peripheral wall  142  that extends downward from the periphery of the planar central portion. Like the overall, generally square, enclosure cap  110 , the depending wall  142  can have four interconnected, orthogonally arranged sides or edges. The lower guide plate  134  also includes a second central portion  150  and a second depending peripheral wall  152  that also can have four interconnected, orthogonal sides or edges. The vent panels  112  can be formed as rectangular surfaces that are offset or project outwardly from the sides or edges of the first and second depending peripheral walls  142 ,  152  of the respective upper shield plate  132  and lower guide plate  134 . 
     To help direct heated air out of the enclosure through the vents, the central portion  150  of the lower guide plate  134 , unlike the planar central portion  140  of the upper shield plate  132 , can have a contoured shape. When the lower guide plate  134  is joined to the upper shield plate  132 , the contoured shape can provide an internal cavity forming the air gap  130 . In the illustrated embodiment, the contoured portion  150  has a depending or drooping shape in which the contoured portion extends from the upper edge of all four sides of the peripheral wall  152  and curves or arcs inward and downward so as to form a cusp-like drooping center point  160  located generally at the center of the lower guide plate. In this case, the drooping center point  160  extends downward to a location below the upper edges of the peripheral wall  152  from which the contoured portion  150  extends. 
     In the present embodiment, as illustrated best in  FIGS. 6 and 7 , the contoured central portion  150  further includes four separate curving surfaces or lobes  162  each of which are associated with one of the four sides of the peripheral wall  152 . The lobes  162  can curve or arc to intersect together in a cusp that is the drooping center point  160 . The illustrated contoured portion  150  also includes four depressed troughs  164  that extend inwardly from each of the four corners  126  of the lower guide plate  134  and intersect at the drooping center point  160 . As illustrated best in  FIGS. 4 and 6 , the troughs  164  generally form a cross within the generally square lower guide plate  134  and can partition the four lobes  162  into distinct, generally triangular shapes. 
     Referring to  FIGS. 7 ,  8  and  9 , the contoured portion  150  provides the lower guide plate  134  with a vault-like appearance including, at a location corresponding to the horizontal midline of the enclosure cap  110 , curved arches  166  corresponding to the contoured lobes  162  that intersect at the drooping center point  160 . When the lower guide plate  134  and upper shield plate  132  are joined together, the lower guide plate can be received within and accommodated by the upper guide plate such that the first and second depending peripheral walls  142 ,  152  can be in adjacent contact with each other. As illustrated, the first depending peripheral wall  142  of the upper shield plate  132  generally surrounds and holds the second depending peripheral wall  152  of the lower guide plate  134 . However, the overall contour of the contoured portion  150  including the curved arches  166  and the cusp-like drooping center point  160  partially separates and spaces the lower guide plate from the generally planar central portion  140  of the upper shield plate  132 . Hence, the drooping center point  160  and the troughs  164  assist in defining the internal cavity that serves as the air gap  130 . 
     Referring back to  FIG. 2 , when the cap  110  is installed on a pedestal-style enclosure  100 , the upper shield plate  132  is exposed to the environment and can be made of a material or with a color that deflects some of the impinging solar radiation. The lower guide plate  134  is exposed to the interior of the enclosure  100  and generally separates the air gap  130  from the interior and electronic components located therein. Accordingly, the air gap  130  is positioned to further buffer or insulate the interior  108  of the enclosure from solar radiation. In an embodiment, the air gap  130  can be sealed off from the outside environmental air. Referring to  FIGS. 7 ,  8  and  9 , this can be accomplished by placing the first and second depending peripheral sidewalls  142 ,  152  in continuous contact about the entire periphery of the cap  110 . The contiguous peripheral sidewalls  142 ,  152  seal the air gap  130  from the exterior of the enclosure. In another embodiment, to allow for thermal expansion of heated air within the air gap  120 , the lower guide plate  124  can include one or more small holes  170  that establish communication between the air gap and the interior of the enclosure  100 . The expanding heated air in the air gap  130  can move into the interior of the enclosure, thereby reducing pressure buildup within the air gap. As can be appreciated, in this embodiment, allowing for thermal expansion of air within the air gap can help prevent damage to the enclosure cap. Even considering the holes  170 , it will be appreciated that the air gap  130  may remain substantial confined by the cap structure and substantially separated from the interior of the enclosure. 
     In another aspect of the disclosure, the contour of the lower guide plate  134  can facilitate the chimney effect of the pedestal-style enclosure  100 . Specifically, the interrelation of the curves and arcs of the interior surface of the lower guide plate can function to direct hot air from the interior volume toward the exhaust vents. Referring back to  FIG. 2 , the interior surface of the contoured central portion  150  of the lower guide plate  134  is exposed to the interior  108  of the enclosure  100  when the cap  110  is installed on the top of the pedestal enclosure. The drooping center point  160  and the four troughs  164  depend downwardly toward the interior  108  while the curved arches  166  corresponding to the lobes arc upwardly and outwardly to the offset vent panels  112  formed into the depending peripheral sidewalls  142 ,  152 . As heated air from the interior  108  of the enclosure  100 , indicated by arrows  172 , rises up the pedestal and encounters the guide plate  134 , the arches  166  can direct the rising air outwardly toward the vent panels  112  and back down out the clearances  116 . Hence, the lower guide plate functions as a guide or deflector to the heated air. As can be appreciated, this facilitates the circulation of air through the enclosure. The heated air being directed along the arches  166  can encounter and carry outwardly to the vents the heated air from the gap  130  that moves into the interior  108  through holes disposed in the lower guide plate because of thermal expansion. In various embodiments, the interior surface of the lower guide plate can be metalized or otherwise treated to improve its heat resistance properties. 
     In another aspect of the disclosure, the enclosure cap can be of a monolithic or single piece construction. In such a monolithic cap, the upper shield plate and the lower guide plate are formed from the same part and need not be joined by fasteners or adhesive. A preferred method of producing such a monolithic cap is through a double walled, blow molding process. In this process, a thermoplastic blank or pre-form is placed between two mold walls, one of which has a shape corresponding to the upper shield plate and the other of which has a shape corresponding to the lower guide plate. The thermoplastic blank may then be heated and pressurized air can be injected from a needle into the pre-form causing it to inflate against the walls of the mold thus taking the shape of the mold. As can be appreciated from  FIGS. 6 ,  7 , and  8 , the inflated interior of the blank can correspond to the air gap  130  while the layers of the blank pressed against the mold walls correspond to the upper shield plate  132  and the lower guide plate  134 . The molded plastic part is then ejected from the mold and can be subjected to further processing or treating steps. Other manufacturing methods for producing a monolithic cap include a 2-shot injection molding process and the co-extrusion of plastic material together. 
     Referring to  FIGS. 10 and 11 , there is illustrated another embodiment of a pedestal style electronics enclosure  200  which is shaped as an elongated, upright cylinder. The enclosure  200  can include a circular, canister-like housing  202  with an open top end  204  and a closed bottom end  206  that defines an interior volume  208  in which the electronic devices can be housed. To enclose the interior  208 , there is positioned on the top end  204  of the housing  202  an enclosure cap  210 . To match the cylindrical shape of the housing  202 , the enclosure cap  210  can have a corresponding circular shape. The enclosure cap  210  can have a generally dome-like appearance with a circular or round downward depending sidewall  220  and can generally be set or installed atop of the uppermost circular rim  209  of the canister-like housing  202 . 
     To exhaust the air which is heated by the electronics enclosed in the interior  208  of the enclosure housing  202 , the enclosure cap  210  can be configured to include one or more vents that facilitate the chimney effect. To form the vents, the cap  210  can include one or more offset vent panels  212 . To accommodate the circular shape of the cap, the vent panels  212  are formed as various arcs or segments of the circular sidewall  220  that protrude outwardly. The individual vent panels  212  are separated from one another by one or more indentations  214  that are formed into the circular sidewall  212 . When the enclosure cap  210  is positioned on the top end  204  of the enclosure housing  202 , the vent panels  212  are offset with respect to and spaced apart from the upper rim  209  of the housing thereby providing clearances  216  between the vent panels and the housing sidewall. As described above, the clearances  216  establish communication between the interior  208  of the housing  202  and the surrounding environment to allow hot air rising in the housing to escape therefrom. Screens, mesh or similar features can be included to prevent foreign objects from entering the interior via the clearances. 
     Referring to  FIGS. 12 ,  13 , and  14 , the circular enclosure cap  210  can have a generally dish-like or bowl-like shape with the round or circular sidewall  220  providing its height. The cap  210  can include an exterior surface  222  that provides in part the rounded, dome-like appearance and an interior surface  224  that, as described below, may be contoured or shaped to assist in venting of the heated air. When the cap  210  is installed on the pedestal housing, the exterior surface  222  will be directed upwardly and exposed to the environment while the interior surface  224  will be exposed to the interior. Additionally, the indentations  214  separating the vent panels  212  can correspond in location with and can even provide in part one or more inwardly directed bosses  228  which, when the cap is positioned on top of the housing, can rest or sit atop of the uppermost rim. 
     Referring to  FIGS. 15 and 16 , in an aspect of the disclosure, to buffer or insulate the interior of the enclosure from being heated by solar radiation impinging upon the exterior surface of the enclosure cap  210 , the present embodiment of the cap can be formed as a hollow structure with an internal chamber or air gap  230  substantially enclosed within the cap structure. In the illustrated embodiment, the cap  210  can include an upper shield plate  232  and a lower guide plate  234  that are joined together and in between which is provided the air gap  230 . The upper shield plate  232  corresponds to the dome-like exterior surface  222  of  FIG. 12  while the lower guide plate  234  corresponds to the contoured inner surface  224  of  FIG. 13 . Both the upper shield plate  232  and the lower guide plate  234  may have an overall circular shape corresponding to the circular shape of the enclosure cap  210 . 
     The upper guide plate  232  can have a rounded or humped central portion  240  that provides a slight, upwardly directed dome and a first depending peripheral wall  242  that extends downwardly from the central portion. In the illustrated embodiment, the peripheral wall  242  is circular. The lower guide plate  234  can also have a central portion  250  and a second depending peripheral wall  252  extending downwardly. When the upper shield plate  232  is joined to the lower guide plate  234 , as illustrated in  FIG. 16 , the first and second depending peripheral walls  242 ,  252  extend generally coextensively and adjacently with each other such that the upper shield plate  232  appears to receive and retain the lower guide plate  234 . In various embodiments, the depending peripheral walls can be intimately joined about the circular circumference to thoroughly enclose and seal the internal air gap. 
     The contoured central portion  250  of the lower guide plate  234  arcs or curves inwardly from the peripheral side  252  toward a centrally located drooping point  260  proximate the radial center of the circular enclosure  210 . The drooping center point  260  forms a cusp that is directed downwardly and away from the central portion of the upper shield plate  232 . The air gap  230  is thereby formed between the central portions  240 ,  250  of the upper shield plate  232  and the lower guide plate  234  which are directed away and spaced apart from each other. When the hollow enclosure cap  210  is installed on the housing  202  as illustrated in  FIG. 11 , the upper shield plate  232  can deflect some of the impinging radiation from the sun back to the environment. The lower guide plate  234  separates the air gap  230  from the interior  208  of the housing so that the air gap is positioned to buffer or further insulate the interior. In various other embodiments, the air gap can be completely sealed from the interior and the surrounding environment, can be slightly vented to the environment, and/or can be in communication with the interior via one or more smaller holes disposed through the lower guide plate. 
     In another aspect of the disclosure, to assist in venting air from the interior, the contoured central portion  250  provides the lower guide plate  234  with a vault-like appearance including a curved arch  266  that arcs from the depending peripheral wall  252  to the drooping center point  260 . The arch  266  can extend about or around the drooping center point  260  so as to form the shape of a torus that has been planed in half. When the enclosure cap  210  is installed on the housing as illustrated in  FIG. 11 , the drooping center point  260  is directed downwardly toward the interior and the annularly extending arch  266  is generally directed upwards. Heated air indicated by arrows  272  rising upwards in the housing  202  will encounter the contoured lower guide plated  234  and can be directed by the arch  266  toward the vent panels  212  and back down and out the clearance  216 . Thus, the contoured lower guide plate  234  can function to deflect or direct hot air out the top end of the enclosure to facilitate the chimney effect. The circular enclosure cap can be made of any suitable material, such as plastic, and can be manufactured by any suitable process, including the double-walled blow molding process described above. Additionally, the circular enclosure cap can be formed as a monolithic, single piece part or component. 
     Accordingly, the invention provides a cap for an electronics enclosure that is designed with beneficial thermal control features. For example, in an embodiment, the enclosure cap can be hollow and include an air gap that assists in insulating the interior of the enclosure from solar radiation. In another embodiment, the interior surface of the enclosure cap can be contoured so as to direct heated air rising in the interior of the enclosure toward one or more vent panels for exhaustion to the environment. In a preferred embodiment, the enclosure cap can be a monolithic or single piece design and can be produced by a thermoplastic blow molding process. 
     All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. 
     The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
     Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.