Patent Publication Number: US-11040867-B2

Title: System, method and apparatus for minimizing dead legs in a bioreactor system

Description:
BACKGROUND 
     Technical Field 
     Embodiments of the invention relate generally to bioprocessing systems and methods and, more particularly, to devices for minimizing or preventing dead leg spaces in bioprocessing systems. 
     Discussion of Art 
     In the biopharmaceutical industry, increasingly, single-use or disposable containers or flexible bags are used. Such containers can be flexible or collapsible plastic bags that are supported by an outer rigid structure such as a stainless steel shell, referred to herein as a “vessel.” The use of sterilized, disposable bags eliminates the time-consuming step of cleaning the steel bioreactor vessel and reduces the chance of contamination. In use, the bag is filled with the desired fluid for mixing, and an impeller disposed within the bag (driven by a magnetic drive system or motor positioned outside the vessel) is used to mix the fluid. Depending on the fluid being processed, the system may include a number of fluid lines and different sensors, probes and ports coupled with the bag for monitoring, analytics, sampling, and fluid transfer. For example, a harvest port is typically located at the bottom of the disposable bag and the vessel, and allows for a harvest line to be connected to the bag for harvesting and draining of the bag after the bioprocess is complete. 
     Currently available single-use bioreactors utilize hose barb or similar fittings that are welded to the bag film as entry and exit points for conveyance of fluid. The drain line fitting generally has a tubular portion that provides for one-way fluid flow. Media flows into the tubular portion of the fitting, where media, cells and other fluid components can settle and remain isolated from the bulk bioreactor environment. When cells collect in this portion of the fitting, they are generally deprived of nutrients, die, and release toxic compounds that can be detrimental to the growth and production of cells in the bulk culture. When this occurs, the area in which the media and cells collect is referred to as a dead leg or a dead leg space. For mixing systems, minimizing dead leg spaces promotes complete mixing and reduces potential sedimentation of solids. 
     At present, there is no effective means for preventing or completely eliminating this isolated volume of fluid and cells in a dead leg portion of a drain fitting. Existing systems typically employ a non-invasive pinch valve, whereby a clamp or other means is utilized to clamp the drain line to close the channel in the drain line tubing, however, fluid may still gather and settle in the space above the clamp. 
     In view of the above, there is a need for devices and methods for preventing or substantially minimizing dead leg spaces in the drain line or drain fitting of bioprocessing systems that employ single-use, flexible bioreactor containers. 
     BRIEF DESCRIPTION 
     In an embodiment, an apparatus for minimizing dead leg spaces in a container or tubing is provided. The apparatus includes a first member having a flange for attaching the first member to a wall of the container or tubing, the flange having at least one aperture, and a second member rotatably coupled to the first member, the second member having an upper end having at least one aperture, and an open distal end. The second member is rotatable relative to the first member between a closed position where the at least one aperture of the second member is misaligned with the at least one aperture in the flange to prevent the passage of fluid, and an open position where the at least one aperture of the second member is aligned with the at least one aperture in the flange to allow for the passage of fluid. 
     In another embodiment, an apparatus for minimizing dead leg spaces in a container or tubing includes a first member having a flange for attaching the first member to a wall of the container or tubing, and a generally hollow sleeve extending from the flange, and a plunger slidably received within the hollow sleeve, the plunger having a tip configured to sealingly engage the first member. The plunger is slidable between a closed position where the tip sealingly engages the sleeve adjacent to the flange to prevent the passage of fluid into the sleeve, and an open position where the plunger is linearly displaced from the closed position to allow for the passage of fluid into the sleeve. 
     In yet another embodiment, an apparatus for minimizing dead leg spaces in a container or tubing includes a first member having a flange for attaching the first member to a wall of the container or tubing, a generally hollow sleeve extending from the flange, and a sealing element extending across the sleeve for sealing off a passage through the sleeve, and a generally hollow piercing member slidably received within the hollow sleeve, the piercing member having a piercing tip. The piercing member is movable between a first position where the piercing tip is positioned below the sealing element whereby the sealing element remains intact to prevent the passage of fluid beyond the sealing element, and a second position where the piercing member pierces the sealing element and the piercing tip extends into the container or tubing and an interior of the piercing member is in fluid communication with an interior of the container or tubing to allow for passage of fluid into the hollow piercing member and beyond the sealing element. 
     In yet another embodiment, an apparatus for minimizing dead leg spaces in a container or tubing includes a flange for attaching the first member to a wall of the container or tubing, the flange including an opening, a main body connected to the flange, the main body having a passageway in fluid communication with the opening in the flange, a connection member connected to the main body for connecting drain tubing to the apparatus, and a valve positioned within the passageway, the valve being actuatable between a closed position in which fluid flow through the passageway is prevented, and an open position in which fluid flow through the passageway is allowed. 
    
    
     
       DRAWINGS 
       The present invention will be better understood from reading the following description of non-limiting embodiments, with reference to the attached drawings, wherein below: 
         FIG. 1  is a front elevational view of a bioreactor system according to an embodiment of the invention. 
         FIG. 2  is a perspective view of an apparatus for minimizing dead leg spaces in a bioprocessing system, according to an embodiment of the invention. 
         FIG. 3  is a perspective, cross-sectional view of an upper member of the apparatus of  FIG. 2 . 
         FIG. 4  is a perspective, cross-sectional view of a lower member of the apparatus of  FIG. 2 . 
         FIG. 5  is a partial cutaway, top plan view of the apparatus of  FIG. 2 , illustrating a closed position whereby fluid flow is prevented. 
         FIG. 6  is a partial cutaway, top plan view of the apparatus of  FIG. 2 , illustrating an opening position whereby fluid flow is enabled. 
         FIG. 7  is a perspective view of another apparatus for minimizing dead leg spaces in a bioprocessing system, according to another embodiment of the invention, showing an open position whereby fluid flow is enabled. 
         FIG. 8  is a perspective view of the apparatus of  FIG. 7 , showing a closed position whereby fluid flow is prevented. 
         FIG. 9  is an enlarged, detail view of area A of  FIG. 8 . 
         FIG. 10  is a side, cross-sectional view of the apparatus of  FIG. 7 . 
         FIG. 11  is a perspective view of another apparatus for minimizing dead leg spaces in a bioprocessing system, according to another embodiment of the invention. 
         FIG. 12  is a side, cross-sectional view of the apparatus of  FIG. 11 . 
         FIG. 13  is a perspective view of another apparatus for minimizing dead leg spaces in a bioprocessing system, according to another embodiment of the invention. 
         FIG. 14  is a perspective view of the apparatus of  FIG. 13 , showing a closed position whereby fluid flow is prevented. 
         FIG. 15  is a perspective view of the apparatus of  FIG. 13 , showing an open position whereby fluid flow is enabled. 
         FIG. 16  is a side, cross-sectional view of an apparatus for minimizing dead leg spaces in a bioprocessing system according to another embodiment of the invention, showing a closed position whereby fluid flow is prevented. 
         FIG. 17  is a side, cross-sectional view of the apparatus of  FIG. 16 , showing an open position whereby fluid flow is enabled. 
         FIG. 18  is a side, cross-sectional view of an apparatus for minimizing dead leg spaces in a bioprocessing system according to another embodiment of the invention, showing a closed position whereby fluid flow is prevented. 
         FIG. 19  is a side, cross-sectional view of the apparatus of  FIG. 18 , showing an open position whereby fluid flow is enabled. 
         FIG. 20  is an enlarged, cross-sectional view of a piercing tip of the apparatus of  FIG. 18 . 
         FIG. 21  is a perspective view of a spike member of the apparatus of  FIG. 18 . 
         FIG. 22  is a perspective view of a protection element for use with the apparatus of  FIG. 18 , according to an embodiment of the invention. 
         FIG. 23  is a perspective view of a protection element for use with the apparatus of  FIG. 18 , according to another embodiment of the invention. 
         FIG. 24  is a perspective illustration of an apparatus for minimizing dead leg spaces in a bioprocessing system according to another embodiment of the invention. 
         FIG. 25  is a schematic illustration of a flexible bag of a bioprocessing system, employing the apparatus of  FIG. 24 . 
         FIG. 26  is a schematic illustration of an apparatus for minimizing dead leg spaces in a bioprocessing system, according to another embodiment of the invention. 
         FIG. 27  is an enlarged, detail view of a sealing interface of the apparatus of  FIG. 26 . 
         FIG. 28  is a schematic illustration of an apparatus for minimizing dead leg spaces in a bioprocessing system, according to another embodiment of the invention. 
         FIG. 29  is a perspective view of an apparatus for minimizing dead leg spaces in a bioprocessing system according to another embodiment of the invention. 
         FIG. 30  is a cross-sectional view of the apparatus of  FIG. 29 . 
         FIG. 31  is a schematic illustration of an apparatus for minimizing dead leg spaces, employing a septum, according to an embodiment of the invention. 
         FIG. 32  is a side, cross-sectional view of an apparatus for minimizing dead leg spaces in a bioprocessing system according to another embodiment of the invention, showing a closed position. 
         FIG. 33  is a side, cross-sectional view of the apparatus of  FIG. 32 , showing an open position. 
         FIG. 34  is a side, cross-sectional view of an apparatus for minimizing dead leg spaces in a bioprocessing system, according to another embodiment of the invention, showing a closed position. 
         FIG. 35  is a side, cross-sectional view of the apparatus of  FIG. 34 , showing an open position. 
         FIG. 36  is a cross-sectional, perspective view of an apparatus for minimizing dead leg spaces in a bioprocessing system, according to another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will be made below in detail to exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference characters used throughout the drawings refer to the same or like parts. 
     As used herein, the term “flexible” or “collapsible” refers to a structure or material that is pliable, or capable of being bent without breaking, and may also refer to a material that is compressible or expandable. An example of a flexible structure is a bag formed of polyethylene film. The terms “rigid” and “semi-rigid” are used herein interchangeably to describe structures that are “non-collapsible,” that is to say structures that do not fold, collapse, or otherwise deform under normal forces to substantially reduce their elongate dimension. Depending on the context, “semi-rigid” can also denote a structure that is more flexible than a “rigid” element, e.g., a bendable tube or conduit, but still one that does not collapse longitudinally under normal conditions and forces. 
     A “vessel,” as the term is used herein, means a flexible bag, a flexible container, a semi-rigid container, a rigid container, or a flexible or semi-rigid tubing, as the case may be. The term “vessel” as used herein is intended to encompass bioreactor vessels having a wall or a portion of a wall that is flexible or semi-rigid, single use flexible bags, as well as other containers or conduits commonly used in biological or biochemical processing, including, for example, cell culture/purification systems, mixing systems, media/buffer preparation systems, and filtration/purification systems, e.g., chromatography and tangential flow filter systems, and their associated flow paths. As used herein, the term “bag” means a flexible or semi-rigid container or vessel used, for example, as a bioreactor or mixer for the contents within. 
     Embodiments of the invention provide various devices for minimizing dead leg in a drain port or drain line tubing of a flexible, single-use bioprocessing bag and/or achieving zero dead leg (preventing dead leg) in a drain port or drain line tubing of a flexible, single-use bioprocessing bag. As used herein, “minimizing dead leg” refers to the condition of decreasing a dead leg volume of the drain port or drain line tubing (i.e., a volume of a non-circulating length of tubing or a volume of a container in which there is no movement of liquid) as compared to the dead leg volume in the absence of the use of the apparatuses of the present invention (where a clamp may have been typically used). While embodiments of the invention are described in connection with flexible, single-use bioprocessing bags for use in the biopharmaceutical industry, it is contemplated that the devices, systems and methods for preventing or minimizing dead leg spaces described herein can likewise be used in containers, containers, tubing and vessels, more generally. As used here, the terms “upper member” and “first member” are used interchangeably to refer to the same components, as are the terms “lower member” and “second member”. 
     With reference to  FIG. 1 , a bioreactor system  10  according to an embodiment of the invention is illustrated. The bioreactor system  10  includes a generally rigid bioreactor vessel or support structure  12  mounted atop a base  14  having a plurality of legs  16 . The vessel  12  may be formed, for example, from stainless steel, polymers, composites, glass, or other metals, and may be cylindrical in shape, although other shapes may also be utilized without departing from the broader aspects of the invention. The vessel  12  may be outfitted with a lift assembly  18  that provides support to a single-use, flexible bag  20  disposed within the vessel  12 . The vessel  12  may include one or more sight windows  22 , which allows one to view a fluid level within the flexible bag  20 , as well as a window  24  positioned at a lower area of the vessel  12 . The window  24  allows access to the interior of the vessel  12  for insertion and positioning of various sensors and probes (not shown) within the flexible bag  20 , and for connecting one or more fluid lines to the flexible bag  20  for fluids, gases, and the like, to be added or withdrawn from the flexible bag  20 . Sensors/probes and controls for monitoring and controlling important process parameters include any one or more, and combinations of: temperature, pressure, pH, dissolved oxygen (DO), dissolved carbon dioxide (pCO 2 ), mixing rate, and gas flow rate, for example. The vessel  12  may also include an opening in the bottom thereof, allowing for drain or discharge tubing  26  to connect with the flexible bag  20  via welding or other connectors for draining and/or harvesting the contents of the flexible bag  20 . 
     In embodiments of the invention, the drain outlet of the flexible bag  20  may be configured or outfitted with a device configured to minimize or prevent dead leg spaces in the drain tubing  26 , associated connectors and/or adjacent areas of the flexible bag  20 .  FIGS. 2-6  illustrate one possible configuration of an apparatus  100  that can be integrated with the flexible bag  20  to prevent dead leg spaces in the flexible bag  20  and discharge tubing  26 . As shown therein, the apparatus  100  includes a first, upper member  110  and a second, lower member  112  that is configured for rotatable coupling to the upper member  110 . With specific reference to  FIGS. 2 and 3 , the upper member  110  includes an annular flange  114  and a hollow stem  116  that extends downwardly from the flange  114 . The flange  114  includes a plurality of apertures  118  formed therein that are each spaced a radial distance from a central axis  120  of the upper member  110  and provide a passageway for a fluid to pass through the flange  114  and into the interior portion of the hollow stem  116  as discussed below. The distal end of the stem  116  also includes at least one projection or pin  121  extending outwardly therefrom, the purpose of which will be described hereinafter. 
     As shown in  FIG. 4 , the lower member  112  includes a generally tubular body portion  122  having a generally closed upper end  124  and an open bottom end  126 . The upper end includes a plurality of apertures  128  formed therein that are each spaced a radial distance from a central axis  131  of the lower member  112  that corresponds to the distance that the apertures  118  of the upper member  110  are spaced from central axis  120 . In addition, the angular spacing of apertures  128  of the lower member  112  corresponds to the angular spacing of the apertures  118  of the upper member  110 . As further shown in  FIG. 4 , the body portion  122  includes an outwardly spaced annular sleeve or sidewalls  130  defining an annular slot  132  for receiving the stem  116  of the upper member  110 . In this respect, the inner diameter of the sleeve  130  generally corresponds to the outer diameter of stem  116 , and the inner diameter of the stem  116  generally corresponds to the outer diameter of the body portion  122 . As alluded to above, and as shown in  FIGS. 5 and 6 , the lower member  112  also includes a keyway  136  configured to receive the projection  121  of the upper member  110  for selectively locking the apparatus in an open and/or closed position. In an embodiment, the distal end  126  of the lower member  112  may include a hose barb connection  134  (or TC connection) for connection to drain tubing  26 , as shown in  FIG. 2 . 
     Referring still further to  FIG. 2 , the flange  114  is sealingly attached to the inner surface of the flexible bag  20 , such as by welding, although other means of attachment may also be utilized without departing from the broader aspects of the invention. The stem  116  of the upper member  110  is slidably and rotatably received within the annular slot  132  in the lower member  112 . In use, flexible bag  20  with integrated apparatus  100  is positioned within a bioreactor vessel  12  such that apparatus  100  extends through the drain opening/aperture in the bottom of the vessel  12  and is connected to drain tubing/line  26 , as illustrated in  FIGS. 1 and 2 . 
     With reference to  FIGS. 5 and 6 , the lower member  112  is rotatable relative to the upper member  110  to selectively align (or misalign) the apertures  118 ,  128 . In particular, prior to filling the flexible bag  20  with process media and prior to commencing bioprocessing, the lower member  112  is rotated to a closed position so that apertures  128  in the lower member  112  are not aligned with the apertures  118  in the upper member  100 , as shown in area A of  FIG. 5 . This orientation prevents fluid flow through the apparatus  100  and out of the flexible bag  20 . Because the flange  114  of the upper member  110  is substantially planar with the bottom of the flexible bag  20 , dead leg spaces at a location lower than the bottom of the flexible bag  20 , such as in discharge tubing  26 , are prevented or substantially minimized. After processing, or at any time desired, the lower member  112  may be rotated relative to the upper member  110  to bring the apertures  118  in the upper member  110  into alignment with the apertures  128  in the lower member, as shown in area B of  FIG. 6 , which allows fluid to flow from the flexible bag  20 , through the apparatus  100 , and into the connected discharge/drain tubing  26 . In an embodiment, the projection  121  and keyway  136  are operable to lock the apparatus  100  in this open position. 
     The apparatus  100  is therefore selectively operable to prevent or allow fluid flow from the flexible bag  20  and into the drain tubing  20 . In the closed position, where the apertures are misaligned, because flange  114  and apertures  118 ,  128  are substantially flush with the bottom of the flexible bag  20 , no fluid is permitted to pass by the flange  114  and collect outside the primary volume of the flexible bag  20  (i.e., outside of the regulated bioreactor environment), such as in the drain tubing  26 . In an embodiment, it is contemplated that the lower member  112  may be connected to a motor or other rotational drive mechanism  180 , allowing for automated control over the position of the apparatus  100 . 
       FIGS. 7-10  illustrate another configuration of an apparatus  200  that can be integrated with the flexible bag  20  to prevent or minimize dead leg spaces in the flexible bag  20  and discharge tubing  26 . As illustrated therein, the apparatus  200  is generally similar in configuration and operation to the apparatus  100  of  FIGS. 2-6 , and includes an upper member  210  and a lower member  212  that is rotatably coupled to the upper member  210 . The upper member  210  has an annular flange  214 , a short, hollow stem  216  that extends downwardly from the flange  214 , and a pair of resilient arms  218  extending downwardly from the stem  216 . In an embodiment, the resilient arms  218  are spaced approximately 180 degrees apart and include projections  220  and their respective distal ends that extend towards a center line or central axis  222  of the apparatus  200 . As illustrated in  FIG. 7 , the flange  214  includes at least one aperture  224  formed therein, which provides a passageway for a fluid to pass through the flange  214  and into the interior portion of the hollow stem  216 , as discussed below. In an embodiment, the aperture  224  is a half-circle in shape, although other shapes may be utilized without departing from the broader aspects of the invention. 
     With further reference to  FIG. 7 , the lower member  212  includes a generally hollow, tubular body portion  226  having an upper end  227  with an aperture  228  formed therein and a generally open bottom end  230 . In an embodiment, the aperture  228  is, like aperture  224 , half-circle in shape, although other shapes are possible. As shown in  FIGS. 7 and 9 , the body portion  226  of the lower member  212  also includes a circumferential groove  232  that defines a shoulder  234 . The circumferential groove  232  is interrupted by at least one position stop  236 , the purpose of which will be described hereinafter. With reference to  FIG. 10 , the upper portion of the lower member  212  may also include a sealing element  238  disposed in a circumferential groove  240 . In an embodiment, the distal end  230  of the lower member  212  may include a hose barb connection  242  for connection to drain tubing (not shown). 
     As best shown in  FIG. 10 , the flange  214  of the upper member  210  is sealingly attached to the inner surface of the flexible bag  20 , such as by welding, although other means of attachment may also be utilized without departing from the broader aspects of the invention. The lower member  212  is received within the hollow stem  216  of the upper member  210  such that the O-ring  238  sealingly engages the interior surface of the stem  216  to prevent the passage of fluid therebetween. When the lower member  212  is fully received within the stem  216 , the resilient arms  218  of the upper member  210  are received within the circumferential groove  232  of the body portion  226  of the lower member  212 . In this position, the projections  220  on the ends of the resilient arms  218  contact the shoulder  234 , preventing decoupling of the upper member  210  and lower member  212  from one another. In an embodiment, the apparatus  200  may also include a D-shaped O-ring (not shown) (or other shape configured to correspond to the shape of the apertures  224 ,  228 ) positioned between the apertures  224 ,  228  to allow for fluid sealing between the rotating elements that prevents fluid leakage when in the closed position, as discussed below. 
     In use, flexible bag  20  with integrated apparatus  200  is positioned within a bioreactor vessel  12  such that apparatus  200  extends through the drain opening/aperture in the bottom of the vessel  12  and is connected to drain tubing/line  26 . Referring once again to  FIGS. 7 and 8 , the lower member  212  is rotatable relative to the upper member  210  to selectively align (or misalign) the apertures  224 ,  228 . In particular, prior to filling the flexible bag  20  with process media and prior to commencing bioprocessing, the lower member  212  is rotated to a closed position so that the aperture  228  of the lower member is out of alignment with the aperture  224  in the flange  214 , as shown in  FIG. 8 . In this position, the closed upper surface  227  of the lower member  212  is presented below the aperture  224 . This orientation prevents fluid flow through the apparatus  200  and out of the flexible bag  20 . Because the flange  214  of the upper member  210  is substantially flush with the bottom of the flexible bag  20 , dead leg spaces at a location lower than the bottom of the flexible bag  20 , such as in discharge tubing  26 , are prevented or substantially minimized. After processing, or at any time desired, the lower member  212  may be rotated relative to the upper member  210  in the direction of arrow B to bring the apertures  224 ,  228  into vertical alignment with one another, which allows fluid to flow from the flexible bag  20 , through the apparatus  200 , and into the connected discharge/drain tubing  26 . The position stops  236  functions to prevent over-rotation of the lower member  212 , and are positioned so that when the lower member  212  is rotated in one direction until the projections  220  contact the position stop  236 , the apparatus  200  is in the closed position, and when the lower member  212  is rotated in an opposite direction until the projections  220  contact an opposed position stop  236 , the apparatus  200  is in the open position where the apertures  224 ,  228  are aligned. In this respect, the position stops  236  provide a tactile indication of a fully open and fully closed position of the apparatus  200 . 
     The apparatus  200  is therefore selectively operable to prevent or allow fluid flow from the flexible bag  20  and into the drain tubing  20 . In the closed position, where the apertures are misaligned, because flange  214  and apertures  224 ,  228  are substantially flush with the bottom of the flexible bag  20 , no fluid is permitted to pass by the flange  214  and collect outside the primary volume of the flexible bag  20 , such as in the drain tubing  26 . As discussed above, in an embodiment, it is contemplated that the lower member  212  may be connected to a motor or other rotational drive mechanism, allowing for automated control over the position of the apparatus  200 . Moreover, in an embodiment, the apparatus  200  may include a locking mechanism for selectively locking the apparatus  200  in the open or closed position, as desired. 
       FIGS. 11 and 12  depict another apparatus  300  that can be integrated with the flexible bag  20  to prevent or minimize dead leg spaces in the flexible bag  20  and discharge tubing  26 . The apparatus  300  is substantially similar in configuration and operation to the apparatus  200  of  FIGS. 7-10 , where like reference numerals indicate like parts. As illustrated in  FIG. 12 , however, rather than utilizing resilient arms that are received in a circumferential slot to guide rotation of the lower member with respect to the upper member, apparatus  300  employs a tapered threaded portion  310  (having one of male or female threads) on an external surface of an upper portion of the lower member  212  that is configured to be threadedly received by a corresponding tapered threaded portion  312  (having the other of male or female threads) on an inner surface of the stem  216  of the upper member  210 . In this respect, the upper and lower members  210 ,  212  of the apparatus  300  are threadedly and rotatably coupled to one another. In use, a user can rotate the lower member  212  to selectively align (or misalign) the aperture  228  of the lower member  212  with the aperture  224  of the upper member  210  to facilitate or prevent draining of the bag  20 , as desired. In an embodiment, the apparatus  300  may also include a D-shaped o-ring (not shown) (or other shape configured to correspond to the shape of the apertures  224 ,  228 ) positioned between the apertures  224 ,  228  to allow for fluid sealing between the rotating elements that prevents fluid leakage when in the closed position, as discussed below. 
     Like apparatuses  100  and  200 , it is similarly contemplated that the lower member  212  may be connected to a motor or other rotational drive mechanism, allowing for automated control over the position of the apparatus  300 . 
     Turning now to  FIGS. 13-15 , yet another apparatus  400  for preventing dead leg spaces in a bioprocessing system is illustrated. The apparatus  400  includes an upper member  410  having a generally annular flange  412  and a hollow tube or sleeve  414  that extends downwardly and substantially perpendicularly from the flange  412 . The upper member  410  further includes a Y-leg or branch tube  416  that extends downwardly at an angle from the sleeve  414 . In an embodiment, the branch tube  416  may be a T-leg. As illustrated in  FIG. 13 , a drain line or tubing  26  may be connected to the end of the branch tube  416  using a clamp  418 , although other means of connection such as a hose barb on the distal end of the branch tube  416  may also be utilized without departing from the broader aspects of the invention. In an embodiment, the sleeve  414  may be configured with a radial projection or lug  428 , the purposed of which will be discussed hereinafter. 
     With further reference to  FIGS. 13-15 , the apparatus  400  further includes a plunger  422  that is slidably received by the sleeve  414  through an open bottom end thereof. The plunger  422  has a lower end that terminates in a T-shaped handle  424  providing for ergonomic gripping, and an upper end having a plunger tip  426  having an integrated sealing element that sealingly engages an inner wall of the sleeve  414 . The body of the plunger is configured with relieved portions, fluted portions, or a smaller diameter than the tip  426  to allow for fluid flow past the tip, as discussed hereinafter. As best shown in  FIGS. 14 and 15 , the plunger  422  also includes a keyway  420  that is configured to receive lug  428  on the sleeve  414 . As illustrated in  FIGS. 14 and 15 , the keyway  420  may be generally L-shaped. 
     In use, the flange  412  is attached to the inner surface of the flexible bag  20 , such as by welding, although other means of attachment may also be utilized without departing from the broader aspects of the invention. The drain tubing  26  is then secured to the branch leg  416  and the plunger  422  is received in the sleeve  414  such that the lug  428  is positioned in the keyway  420 . As shown in  FIG. 14 , in a closed position, the plunger tip is seated within the sleeve  414  and generally below the flange  412 , preventing any fluid flow past the flange  412  and out of the flexible bag  20 . In this position, the lug  428  is received in the upper-most part of the keyway  420 . With reference to  FIGS. 13 and 15 , when draining of the bag  20  is desired, the plunger  422  is urged upward in the direction of arrow A, causing the plunger to protrude above the flange  412 , allowing fluid to flow past the tip  426 , into the sleeve  414 , through the branch leg  416  and into the drain tubing  26 . Once the plunger is pushed upwardly to the open position, it can also be rotated in the direction of arrow B, to position the lug  428  within the lower portion/leg of the keyway  420 , as shown in  FIG. 15 . This essentially locks the plunger  422  in the open position, preventing it from moving upwardly or downwardly with respect to the sleeve  414 . 
     While  FIGS. 13-15  illustrate an embodiment whereby the plunger is urged upwardly to break the seal between the plunger tip  426  and the interior of the sleeve  414  to allow fluid to drain from the bag  20 , in other embodiments, the apparatus  400  may be configured so that the plunger can be retracted below the branch leg  416  to allow the contents of the bag  20  to drain into the branch leg  416  and connected drain tubing  26 . Moreover, as alluded to above, in an embodiment, the plunger may be connected to an actuator  480  or motor allowing for automated operation of the apparatus  400 . As discussed above in connection with the previous embodiments, the apparatus  400  eliminates any cavity below the bottom of the flexible bag  20  within which fluid can accumulate. In this respect, the apparatus  400  of the invention prevents dead leg spaces which can adversely affect the batch being processed. 
       FIGS. 16 and 17  illustrate an apparatus  500  according to another embodiment of the invention that can be integrated with the flexible bag  20  to prevent or minimize dead leg spaces in the flexible bag  20  and discharge tubing  26 . The apparatus  500  is substantially similar in configuration and operation to the apparatus  400  of  FIGS. 13-15 . In particular, the apparatus  500  includes an upper member  510  having a flange  512  configured for attachment to flexible bag  20  in the manner described above, and a generally cylindrical and hollow sleeve  514  that extends downwardly from the flange  512 , the sleeve having an open top end  516  and an open bottom end  518 . The apparatus  500  also includes a plunger  520  that is slidably received within the sleeve hollow tube or sleeve  514  through the open bottom end  518 . The plunger  520  has a generally hollow cylindrical first portion  522 , a fluted, second portion  524  extending from the first portion  522 , and a conical tip  526  connected to the second portion  524 . The tip  526  is dimensioned so as to form a fluid-tight seal with the interior sidewalls of the sleeve  514  when the tip is received by the sleeve  514 , as illustrated in  FIG. 16 . In an embodiment, the tip  526  may be covered or formed with silicone. As also shown in  FIG. 16 , the cylindrical portion  522  of the plunger  520  includes one or more sealing elements  528 , such as O-rings, that likewise form a fluid-tight seal with the sleeve  514 . A distal end of the plunger  520  may be formed with a hose-barb connection  530  for connecting drain tubing  26 . 
     With further reference to  FIG. 16 , in a closed position, the tip  526  is retracted within the sleeve  514  and forms a seal with the sleeve  514  to prevent the passage of fluid out of the bag  20 . With reference to  FIG. 17 , when draining of the bag  20  is desired, the plunger may be urged upward, in the direction of arrow A, along a path of travel, B, causing the tip  526  to unseat from the sleeve  514 . In this position, fluid is permitted to flow past the tip, through the fluted portion  524  of the plunger, through the hollow cylindrical portion  522  and into the attached drain tubing  26 . In this manner, the apparatus  500  operates substantially similarly to the apparatus  400  of  FIGS. 13-15 . 
     Referring now to  FIGS. 18-21 , another apparatus  600  for preventing dead leg spaces in a bioprocessing system is illustrated. The apparatus  600  has a generally annular flange  610  configured for connection or integration with the flexible bag  20 , and a connector  612  attached or integrally formed with the annular flange  610 . In an embodiment, the connector  612  is an aseptic connector having a first connector member  614  and a second connector member  616  that matingly interface with one another and form a pierceable or fracturable seal or septum  618  therebetween. In an embodiment, the connector  612  is a ReadyMate™ disposable aseptic connector manufactured by General Electric®. As shown in  FIGS. 18 and 19 , the second connector member  616  is connected with, or integrally formed with, a hollow cylindrical tube or sleeve  620  that extends downwardly therefrom. A distal end of the sleeve  620  includes a flange forming a handle grip  622 . While the connector  612  is illustrated as a two-piece component having a seal therebetween, in an embodiment, the connector may be a single component having a seal element that provides for fluid isolation between the interior of the flexible bag  20  and the sleeve  620 . 
     As further shown in  FIGS. 18 and 19 , the apparatus  600  also includes a hollow spike  624  that is slidably received within the sleeve  620 . As shown in  FIG. 21 , a terminal end of the spike  624  has a pointed, canoe-shaped tip  626  for piercing the seal  618 , as discussed hereinafter. In an embodiment, the tip  626  may have any pointed shape suitable for piercing a thin membrane. An opposite, distal end of the spike  624  has a hose barb connection  628  for connection of drain tubing  26 . In an embodiment, the spike  624  may also include a complementary flange forming a second handle grip  630 . 
     With specific reference to  FIG. 18 , in use, the apparatus  600  is connected to a flexible bioprocessing bag  20  via the annular flange  610  in the manner described above. The hollow spike  624  is slidably received within the sleeve  620  such that the tip  626  is positioned below the seal element  618  of the connector  612 . As illustrated in  FIG. 18 , in an embodiment, a removable clamp  632  may be positioned intermediate the flanges  622 ,  630  on the sleeve  620  and spike  624  to prevent accidental activation (i.e., accidental piercing of the seal element  618 ). In this state, the seal element  618  is positioned generally flush with the bottom of the flexible bag  20 , so that the fluid within the bag  20  is not permitted to enter any cavities or tubing outside of the processing volume of the bag  20 . Accordingly, dead leg spaces where settling can occur are substantially eliminated. Drain tubing  26  may be connected to the hose barb connection  628  on the distal end of the spike  624  either just before draining or at any time before draining after the bag  20  is positioned within the vessel  10 . When it is desired to drain the bag  20  of its contents, the clamp  632  can be removed and the hollow spike  624  may be urged upwards into the bag. This movement of the spike  624  functions to pierce the seal element  618 , causing the tip  626  of the spike  624  to enter the flexible bag  20 , as shown in  FIG. 19 , providing a pathway for fluid to exit the flexible bag  20 . In particular, fluid is able to flow into the hollow spike  624  and out the distal end thereof and into the connected drain tubing  26 . 
     In an embodiment, the apparatus  600  of  FIGS. 18-21  may also employ a device that is configured to protect the integrity of the flexible bag  20  during a draining operation, including during piercing by the spike  624  and during the draining process. For example, as illustrated in  FIGS. 22 and 23 , a protection element  640 ,  650  maybe be positioned in the interior  644  to the flexible bag  20 . The protection element  640 ,  650  may include a flange  646  configured for operative attachment or integration with the interior wall of the flexible bag  20 , and an upstanding cage element  648  having a plurality of apertures  652  or slots  654  formed therein, as the case may be. In an embodiment, the flange  646  may be the same flange or a different flange than flange  610  of apparatus  600 . The cage  648  functions to protect the flexible bag  20  from punctures when the spike is urged through the seal element during draining, and encloses the spike when it protrudes into the bag  20 , preventing contact between the sharp tip of the spike and the bag  20 . In an embodiment, different hole or slot patterns within the cage  648  may be employed to provide for optimal fluid flow. In an embodiment, the protection element  640 ,  650  may further include a cap (not shown) to prevent any cut portion of the bag  20  (which could result from the puncturing operation) from becoming loose inside the bag  20 . 
       FIGS. 24 and 25  illustrate another apparatus  700  that is generally similar in configuration and operation to apparatus  600  described above, and functions to minimize dead leg spaces in a bioreactor or bioprocessing system. As illustrated therein, the apparatus  700  includes a port element  710  having a flange  712  and hollow cylindrical stem  714  depending therefrom. Like the embodiments described above, the flange  712  is configured for connection with the flexible bag  20  so that the stem  714  forms a passageway for fluid out of the bag  20 . As shown in  FIG. 24 , the port element  710  includes a puncturable or fracturable membrane  716  and a flexible septum  718 . While  FIG. 24  depicts the membrane  716  as being located adjacent the flange  712 , the membrane  716  may also be located within the stem  714  to minimize the possibility of accidental puncture. In an embodiment, and with reference to  FIG. 25 , port element  714  may be integrated with the flexible bag  20  at any location at which draining or sampling may be desired, thereby forming a plurality of accessible ports  720 . 
     Referring once again to  FIG. 24 , apparatus  700  may also include a spike  730  for piercing the membrane  716  when accessing the contents of the bag  20  is desired, such as for draining or sampling. In an embodiment, the spike  730  may be substantially similar to spike  624  of  FIGS. 18-21 , and includes a pointed tip  732 , flange  734  for gripping, and hose barb connection  736  for selectively connecting tubing for draining or other processes. 
     In operation, flexible bag  20  may be manufactured with a plurality of ports comprised of port elements  710 . Accessing of the contents of the bag  20  is effectuated by inserting hollow spike  730  into the stem  714  to pierce the membrane  716 . When the spike is urged into the bag  20 , the septum  718  forms a seal around the outer periphery of the spike  730 , preventing leaking. In this position, fluid is permitted to flow into the spike  730  and out of the connected tubing. In yet other embodiments, the septum functions as a self-sealing element, whereby the spike  730  may be thrust into the bag  20  for draining or sampling, and when the spike  730  is retracted or removed, the septum functions to close the opening and prevent fluid leakage. 
     Turning now to  FIG. 26 , in an embodiment, the port element  710  may be utilized in conjunction with a protection element  760  that is positioned interior  762  to the flexible bag  20 . In an embodiment, the protection element  760  may take the form of protection element  640  or  650  shown in  FIGS. 22 and 23  and described above. As described hereinbefore, the protection element  760  functions to prevent inadvertent puncture or tearing of the flexible bag when the spike  730  is urged into the bag  20  during draining. As shown in  FIG. 26 , in embodiments where the apparatus includes a protection element  760 , the membrane  716  may be sandwiched between the flange of the port element and the flange of the protection element. This configuration is more clearly shown in  FIG. 27 . As shown in  FIGS. 26 and 27 , in an embodiment, the spike  730  itself may include a plurality of apertures  764  for the passage of fluid. In particular, the spike  730  may have a plurality of apertures  764  that are placed in close association with the apertures  766  in the protection element  760  when the spike  730  is thrush into the flexible bag  20 . This configuration facilitates fluid flow at low volumes in the bag. 
     With reference to  FIG. 28 , in an embodiment, the spike  730  may be integrated into the port element  710  as a sterile connector. As shown the spike  730  and port connector are substantially similar to those in apparatus  700  described above, however, the apparatus further includes a sterile connection mechanism  770 . In any of the embodiments described above in connection with  FIGS. 24-28 , it is contemplated that the spike  730  may be coupled to an actuator to facilitate automatic piercing of the membrane and entry into the bag. 
     Turning finally to  FIGS. 29-31 , yet another apparatus  800  for minimizing or preventing dead leg spaces in a bioprocessing system is illustrated. The apparatus  800  includes a flange  810  and a generally spherical main body  812  operatively connected thereto. The flange  810  includes an opening  814  in fluid communication with a fluid flow passageway  816  that extends through the main body portion  812 . The main body portion also includes a valve  818  positioned within the fluid flow passageway  816 , and an actuator handle or lever  820  that is rotatable to selectively open or close the valve  818 . In an embodiment, the valve  818  and lever  820  form a stopcock. As shown in  FIGS. 29 and 30 , a lower end of the main body  812  may include a hose barb connection  822  for connecting drain tubing  26  in the manner described above. 
     In use, the apparatus  800  may be operatively connected to the flexible bag  20  via the flange  810  in the manner described above. A user may then rotate the lever  820  to selectively open or close the valve  818  to allow or prevent fluid flow out of the bag  20 . It is contemplated that the apparatus  800  may be used throughout a bioprocess where a drain valve may be opened and closed multiple times. In addition, the openable and closeable nature of the apparatus  800  facilitates the use of the apparatus  800  for both draining and feeding operations. In an embodiment, it is contemplated that the lever  820  may be coupled to an actuator to facilitate automatic operation of the valve  818 . 
     It is contemplated that a septum may be incorporated into the design of any of the apparatuses described herein, such as apparatus  800 , to further minimize any potential dead leg volume.  FIG. 31  illustrates the position of a septum  830  that can be integrated with one or more of the embodiments described herein. 
     Referring now to  FIGS. 32 and 33 , another apparatus  900  for preventing dead leg spaces in a bioprocessing system is illustrated. The apparatus  900  has a generally annular flange  910  configured for connection or integration with the flexible bag  20 , such as through welding, as discussed above. The annular flange  910  includes a depending leg portion defining a generally cylindrical, hollow outer sleeve  912 . Within the outer sleeve  912  is slidably received a hollow inner sleeve  914 . The inner sleeve  914  may include a gasket  916  that is configured to sealingly engage the inner wall of the outer sleeve  912  to prevent a flow of fluid therethrough. As illustrated in  FIG. 32 , the inner sleeve  914  also includes a thin membrane  918  that extends across a top opening of the inner sleeve  914  to prevent a flow of fluid from the bag  20  into the inner sleeve  914 . The apparatus  900  further includes a hollow spike  920  or piercing member in static position within the inner sleeve  914  below the membrane  918 . 
     In operation, to drain the bag  20 , a lower portion of the inner sleeve  914  is gripped and pulled downwardly, in the direction of arrow A. This movement causes the gasket  916  to slide along the inner surface of the outer sleeve  912 . Continued downward urging of the inner sleeve  914  brings the membrane  918  into contact with the sharp tip of the spike  920 , causing the spike to pierce through the membrane  918 , as shown in  FIG. 33 . In this position, the fluid within the bag is permitted to flow past the tear in the membrane  918  and through the spike  920  to drain the contents of the bag  20 . 
     Referring to  FIGS. 34 and 35 , another apparatus  1000  for preventing dead leg spaces in a bioprocessing system is illustrated. The apparatus  1000  is configured to positioned within a drain port  1010  of a flexible processing bag  20 . In an embodiment, the drain port may be configured with an annular flange that is welded to the bag  20  and has a cylindrical outlet opening for draining the contents of the bag, similar to those described above. The apparatus  1000  includes a compressible gasket  1012  (one half of which is shown in  FIGS. 34 and 35 ) positioned within the drain port  1010 , and a clave device/needle  1014  received within a central passageway  1016  of the gasket  1012 . As shown therein, the clave needle  1014  includes a fluid opening  1018  at the top thereof, and a central fluid passageway  1020  extending from the opening  1018  through the needle  1014 . 
     As shown in  FIG. 34 , in a closed position, the opening  1018  is positioned below the bottom surface of the bag  20  (and or a top surface of the gasket  1012 ) so that fluid cannot flow into the opening  1018 . With reference to  FIG. 35 , to drain the bag  20 , the clave needle  1014  is urged upwardly in the direction of arrow A until the opening  1018  is in fluid communication with interior of the bag  20 , enabling the contents to be drained through the opening  1018  and fluid passageway  1020 . As shown therein, upward movement of the clave needle  1014  compresses the gasket  1012 , decreasing the distance, d, of a lateral portion of the gasket, due to the tapered configuration of the external surface of the clave needle  1014 . 
     Referring finally to  FIG. 36 , another apparatus  1100  for preventing dead leg spaces in a bioprocessing system is illustrated. The apparatus  1100  is configured to positioned within a drain port  1110  of a flexible processing bag  20 . In an embodiment, the drain port  1110  may be configured with an annular flange that is welded to the bag  20  and has a cylindrical outlet opening for draining the contents of the bag, similar to those described above. The apparatus  1100  is generally similar to the embodiment shown in  FIGS. 18 and 19  and includes a syringe assembly  1112  which is connected to the bag port  1110  via first and second mating connectors  1114 ,  1116 . The syringe assembly  1112  includes a hollow plunger  1118 , a lower end of which is configured for connection to drain tubing  1120 . Similar to the embodiments described above, the plunger  1118  is slidably upwardly into the bag  20  to allow fluid communication with the openings in the plunger  1118  and the interior of the bag  20 . As shown in  FIG. 36 , seal elements  1122  may form a fluid seal with the interior of the port  1110 . The apparatus  1100  may also include a locking mechanism  1124  (e.g., a latch or L-lock mechanism) and a safety device  1126  that prevents upward travel of the plunger  1118  until the safety device  1126  is removed. The apparatus  1100  may further include a cage element  1128  to protect the bag  20  from puncture when the plunger  1118  is urged upwardly into the interior of the bag. 
     As described herein, embodiments of the invention described can be utilized to prevent or substantially minimize dead leg spaces in a bioprocessing system and, particularly, in the drain tubing an associated connectors or components of the drain system of a bioreactor. By minimizing dead leg spaces, media, cells and other fluid components are prevented from settling in areas where they can be isolated from the main bioreactor environment, which minimizes the likelihood that the cells will be deprived of nutrients and die. Accordingly, by minimizing these dead leg spaces, maximum yield may be achieved and sedimentation is reduced. 
     In an embodiment, an apparatus for minimizing dead leg spaces in a container or tubing includes a first member having a flange for attaching the first member to a wall of the container or tubing, the flange having at least one aperture, and a second member rotatably coupled to the first member, the second member having an upper end having at least one aperture, and an open distal end. The second member is rotatable relative to the first member between a closed position where the at least one aperture of the second member is misaligned with the at least one aperture in the flange to prevent the passage of fluid, and an open position where the at least one aperture of the second member is aligned with the at least one aperture in the flange to allow for the passage of fluid. In an embodiment, the at least one aperture in the flange is a plurality of apertures radially offset from a centerline of the flange, and the at least one aperture in the upper end of the second member is a plurality of apertures corresponding to the plurality of aperture of the flange. The plurality of apertures in the upper end of the second member are at radial and angular locations that correspond to radial and angular locations of the plurality of apertures of the flange. In an embodiment the first member may include one of a keyway and a projection and the second member may include the other of the keyway and the projection, wherein the keyway and the projection are operable to selectively lock the second member in the open position. In an embodiment the first member includes a pair of resilient arms and the second member includes a circumferential groove, wherein the resilient arms engage the circumferential groove and facilitate rotation of the second member between the open position and the closed position. In an embodiment, the circumferential groove includes at least one position stop, the at least one position stop limiting rotation of the second member with respect to the first member. In an embodiment the at least one position stop is located such that rotation of second member to a position where one of the resilient arms contacts the position stop corresponds to the open position of the apparatus. In an embodiment the first member includes a first threaded portion and the second member includes a second threaded portion configured to threadedly engage the first threaded portion to allow rotation of the second threaded portion with respect to the first threaded portion. In an embodiment the distal end of the second member includes a hose barb connector for connecting drain tubing to the apparatus. In an embodiment the container or tubing is a flexible, single-use bioprocessing bag. 
     In another embodiment, an apparatus for minimizing dead leg spaces in a container or tubing includes a first member having a flange for attaching the first member to a wall of the container or tubing, and a generally hollow sleeve extending from the flange, and a plunger slidably received within the hollow sleeve, the plunger having a tip configured to sealingly engage the first member. The plunger is slidable between a closed position where the tip sealingly engages the sleeve adjacent to the flange to prevent the passage of fluid into the sleeve, and an open position where the plunger is linearly displaced from the closed position to allow for the passage of fluid into the sleeve. In an embodiment, the plunger includes at least one relieved area or passageway below the tip allowing for the passage of fluid. In an embodiment, the first member further includes a branch leg extending from the sleeve, the branch leg terminating in a hose barb connector for connection of drain tubing. In an embodiment, the plunger includes one of an L-shaped keyway and a lug and the sleeve includes the other of the keyway and the lug, and the plunger is rotatable and moveable linearly with respect to the sleeve such that when the lug is received in an upper portion of the keyway the plunger is in the closed position, and when the lug is received in a lower portion of the keyway the plunger is locked in the open position. In an embodiment, the plunger includes a handle on a distal end of the plunger. In an embodiment, the container or tubing is a flexible, single-use bioprocessing bag. 
     In yet another embodiment, an apparatus for minimizing dead leg spaces in a container or tubing includes a first member having a flange for attaching the first member to a wall of the container or tubing, a generally hollow sleeve extending from the flange, and a sealing element extending across the sleeve for sealing off a passage through the sleeve, and a generally hollow piercing member slidably received within the hollow sleeve, the piercing member having a piercing tip. The piercing member is movable between a first position where the piercing tip is positioned below the sealing element whereby the sealing element remains intact to prevent the passage of fluid beyond the sealing element, and a second position where the piercing member pierces the sealing element and the piercing tip extends into the container or tubing and an interior of the piercing member is in fluid communication with an interior of the container or tubing to allow for passage of fluid into the hollow piercing member and beyond the sealing element. In an embodiment, the sealing element forms a part of an aseptic connector integrated with the first member. In an embodiment, the apparatus further includes a protection element positioned interior to the container or tubing the protection element having a sidewall that surrounds an opening in the flange to prevent contact of the piercing tip with the container or tubing, and the sidewall includes a plurality of slots or apertures for the passage of fluid. In an embodiment, the piercing member includes a hose barb connector on a distal end of the piercing member for connecting drain tubing to the apparatus. 
     In yet another embodiment, an apparatus for minimizing dead leg spaces in a container or tubing includes a flange for attaching the first member to a wall of the container or tubing, the flange including an opening, a main body connected to the flange, the main body having a passageway in fluid communication with the opening in the flange, a connection member connected to the main body for connecting drain tubing to the apparatus, and a valve positioned within the passageway, the valve being actuatable between a closed position in which fluid flow through the passageway is prevented, and an open position in which fluid flow through the passageway is allowed. 
     In yet further embodiments, a bioprocessing system is provided. The system includes a single-use, flexible bioreactor bag having drain opening or outlet port, and an apparatus or device positioned within the drain opening and attached to the flexible bag, for minimizing dead leg spaces in the flexible bioreactor bag and/or associated drain tubing and/or components. The apparatus may be any one of the apparatuses described above in connection with  FIGS. 2-31 . 
     In yet other embodiments, a method for minimizing dead leg spaces in a container or tubing of a bioprocessing is provided. The method includes positioning a flexible, single-use bioreactor bag within a support vessel, the flexible bioprocessing bag including a device configured to minimize dead leg spaces positioned in an outlet port or drain opening in the flexible bag, and connecting a drain tube to the device. The device may be any one of the apparatuses described above in connection with  FIGS. 2-31 . The method also includes actuating the device to place the interior of the flexible bag in fluid communication with the drain tube so that fluid from the flexible bag may flow through the device and into the drain tube. 
     As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to “one embodiment” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising,” “including,” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property. 
     This written description uses examples to disclose several embodiments of the invention, including the best mode, and also to enable one of ordinary skill in the art to practice the embodiments of invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to one of ordinary skill in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.