Abstract:
A gas measurement system is provided that includes a mechanism for customizing gas supplied to the system. The system further includes a plurality of test locations that can be serviced by a common vessel portion and common sampling and testing infrastructure. The system further includes a controller that is able to control the customization of the supply gas and the location of the common vessel portion.

Description:
PRIORITY 
     The present application claims priority to U.S. Provisional Application No. 61/505,399 filed Jul. 7, 2011, the disclosure of which is incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to a system for gas exchange chambers, and more particularly to method and system for a controlled source gas exchange chamber with automated testing capability. 
     BACKGROUND AND SUMMARY 
     Gas exchange chambers are used to monitor static states of plants and the composition of the immediately surrounding air once plants are allowed to exchange gasses with supplied ambient air. 
     According to an embodiment of the present disclosure, an open gas exchange measuring system is disclosed including: a controller; a test chamber; a customizable gas source that provides gas to the test chamber, the gas source being controlled by the controller, the controller providing for customizing characteristics of the gas provided to the test chamber as desired; and a measuring device. 
     According to another embodiment of the present disclosure, a gas measuring system is disclosed including: a controller; a gas source; a measuring device; a plurality of fixed lower test chamber portions, each lower test chamber portion having a position suitable for receiving a test subject, and a moveable upper test chamber portion. The moveable upper portion being sealable to each of the plurality of lower test chambers; the controller controlling the composition of gas supplied to upper test chamber portion from the gas source, the controller controlling the position of the moveable upper test chamber. 
     According to another embodiment of the present disclosure, a gas measuring system is provided including: a test chamber; a gas source; a first test chamber portion; a second test chamber portion; a third test chamber portion; and a controller including a data storage member. The data storage member including a plurality of instructions thereon that, when invoked by the controller, cause the system to perform the steps of: placing the second test chamber portion in contact with the first test chamber portion; customizing gas flow from the gas source to the first test chamber portion to provide a first gas to the first test chamber portion via the second test chamber portion, the first gas having a first set of desired customized characteristics; moving the second test chamber out of contact with the first test chamber portion and into contact with the third test chamber portion; and customizing gas flow from the gas source to the to the third test chamber portion to provide a second gas to the third test chamber portion via the second test chamber portion, the second gas having a second set of desired customized characteristics. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned and other features of the disclosure, and the manner of attaining them, will become more apparent and the disclosure itself will be better understood by reference to the following description taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  illustrates a schematic of a system for supplying controlled gasses to one or more of a plurality of plants under test and for measuring gas exchange response; 
         FIG. 2  illustrates a chamber usable in the system of  FIG. 1 . 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate exemplary embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION 
     The embodiments disclosed herein are not intended to be exhaustive or to limit the disclosure to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may utilize their teachings. 
     Referring to  FIG. 1 , an exemplary gas exchange monitoring system  10  is shown. System  10  includes supply buffers  12 , supply pumps  14 , manifold  16 , gas analyzer  18 , chamber  20 , and computer  22 . System  10  is shown as an open system gas exchange chamber, however, it is envisioned that the concepts and teachings herein are also applicable to closed system gas exchange chambers. 
     Supply buffers  12  are gas repositories. Supply buffers  12  are provided with differing gaseous elements having differing physical/chemical characteristics. Buffers  12  are customizable according to tests desired to be carried out. By way of example, four buffers  12  are supplied with varying amounts of CO 2 , O 2 , ambient air, trace gasses (such as ethylene), or any other desired gaseous elements. Each buffer  12  is adjusted by temperature, vapor pressure deficit (VPD), and any other desired characteristic. To this end, heaters, coolers, humidifiers, dehumidifiers, and other condition altering devices  24  are coupled to each buffer  12 . 
     Supply pumps  14  are coupled to each supply buffer  12 . Supply pumps  14  control both the amount of gas supplied from each buffer  12 , the flow rate of supplied gas, and in closed systems, the pressure at which the gas is supplied. 
     Supply pumps  14  supply gas from buffers  12  to manifold  16 . Inputs  26  of manifold  16  are coupled to respective outputs of supply pumps  14 . Manifold  16  combines the outputs from pumps  14 . Manifold  16  further includes valves therein. Accordingly, system  10  is not restricted to supplying only the gaseous states of buffers  12 , but rather combinations of the gaseous states of buffers  12  are achieved by varying the amounts of gas taken and mixed from each buffer  12 . Outlet  28  of manifold  16  is supplied to inlet  30  of chamber  20  and to reference inlet  32  of gas analyzer  18 . 
     Gas analyzer  18  is, in the present example, a CO 2 /H 2 O analyzer, such as one produced by Li-Cor Biosciences with the model number of LI-7000. It should be appreciated that analyzer  18  is chosen to provide for monitoring of the chemicals/variables/features under study. 
     In addition to receiving input from manifold outlet  28 , analyzer  18  receives input from outlet  34  of chamber  20  at sample inlet  33 . Accordingly, analyzer  18  is provided with the gasses being supplied to chamber  20  and the gasses that result from the input gas being subjected to the presence of test subjects  36  (illustrated as plants) within chamber  20 . Chamber outlet  34  is vented to ambient air in opens systems but could be vented to a collection chamber (not shown) or re-circulated in other embodiments. 
     Computer  22  is coupled to analyzer  18  to allow monitoring, saving, and manipulation of the data provided by analyzer  18 . As previously discussed, analyzer  18  includes at least two channels (from manifold outlet  28  and chamber outlet  34 ). Computer  22  includes programming to interface with analyzer  18  and allow graphical presentation of the data received therefrom. Computer  22  is further coupled to chamber  20 , supply pumps  14 , and manifold  16 . Computer  22  is able to control supply pumps  14  and manifold  16  to provide desired gas compositions to chamber  20  at desired times. 
     Chamber  20  is shown in more detail in  FIG. 2 . Chamber  20  includes a fixed lower portion  38  and a moveable upper portion  40 . Lower portion  38  is actually one of a plurality of identical lower portions  38 . Moveable upper portion  40  is selectively associated with a plurality of lower portions  38 . Embodiments are envisioned where system  10  also includes a plurality of upper portions  40 . Test subjects  36  (or plants) under test are located within each lower portion  38 . 
     Lower portions  38  are shown as being cylindrical and presenting an interface portion  42  on an upper lip. While other shapes and orientations are envisioned, lower portions within a system  10  are all similarly shaped and oriented. For example, another such orientation results in lower portions  38  being disposed within the floor or retractable into a floor such that interface portion  42  is flush with the floor. As shown, adjacent lower portions  38  are separated from each other by a defined inter-pot distance  44 . The provided example provides that the inter-pot distance between lower portions  38  is constant for all lower portions  38 .  FIG. 2  shows two lower portions  38  that are separated in a left-right direction of the page. It should be appreciated that lower portions  38  are envisioned as being laid out in a grid of two dimensions (rows and columns), not shown. Accordingly, inter-pot distance  44  corresponds to a column width. The grid also has a row width that may or may not be equal to inter-pot distance  44  (column width). Embodiments are envisioned where the row width is equal to inter-pot distance  44 . In the present example, inter-pot distance  44  is chosen such that the effect that tests being conducted at one lower portion  38  have minimal or no effect on tests being run at a second lower portion  38 . Embodiments are also envisioned where inter-pot distance  44  is chosen to approximate the distance between plants that would be experienced in a planted field. Inter-pot distance  44  also allows for chamber  20  to fully enclose test subject  36  without enclosing any of adjacent test subject  36 . Inter-pot distance  44  is also chosen to allow desired airflow once chamber  20  encloses test subject  36 . Additionally, embodiments are envisioned wherein the floor of lower portion  38  includes a scale. The scale is coupled to computer  22  and provides an electronic weight signal thereto. Additionally, while chamber  20  is discussed as only enclosing one test subject  36  at a time, embodiments are envisioned where multiple test subjects  36  are enclosed together. In such embodiments, test subjects  36  enclosed together are usually of the same type. 
     Upper portion  40  includes base  62 , movement linkages  46 , input/output interfaces  48 , motors  50 , spools  52 , cables  54 , drape  56 , support rings  58 , and interface portion  60 . Base  62  is shown as being a flat square member on which the balance of the pieces of upper portion  40  are mounted. However, it should be appreciated that the depiction of base  62  is conceptual. An actual base  62  is shaped and sized to support and provide mounting surfaces for the balance of the pieces of upper portion  40 . Base  62  is coupled to movement linkages  46 . Movement linkages  46  suspend upper portion  40  above lower portion  38  and test subjects  36 . Movement linkages  46  further allow upper portion  40  to be moved and successively centered over multiple lower portions  38 . Computer  20  is coupled to motors (not shown) that control the movement of movement linkages  46 . 
     Base  62  provides an air-tight coupling to drape  56 . Drape  56  is impervious to gas and illustratively made of a cylinder of flexible transparent plastic of a ply that can sustain repeated flexing. A plurality of support rings  58  is disposed on the interior of drape  56  at varying heights to maintain an internal opening diameter within drape  56 . Alternatively, support rings  58  can take the form of a continual helix that approximates a spring. 
     Lower end  64  of drape  56  is coupled to interface portion  60 . Interface portion  60  is sized to sealingly interface with interface portion  42  of lower portion  38 . The seal of interface portion  42  to fixed lower portion  38  is air-tight to provide a volume within drape  56  that is gaseously isolated from the surrounding air. 
     Cables  54  are coupled to lower end  64  of drape and extend vertically upwardly to base  62 . Cables  54  are further coupled to spools  52  that are coupled to and rotatable relative to base  62 . Spools  52  are coupled to motors  50  that selectively turn spools to wind and unwind cables  54  from spools  52 . Such winding and unwinding of cables  54  from spools  52  raise and lower, respectively, the interface portion  60  and drape  56 . Accordingly, drape  56  is provided a lowered position where interface portion  60  seals to interface portion  42 . Likewise, drape  56  is provided a raised position where interface portion  60  is disengaged from interface portion  42  and lower end  64  is raised to a height higher than the height of test subjects  36 . The raised position of drape  56  causes/allows flexing of drape  56  to a compressed orientation. 
     Alternatively, embodiments are envisioned where harder plastic is used for drape  56 . Such embodiments use the harder plastic in a telescoping manner such that collapsed (retracted) and expanded orientations are again provided. Air-tight seals are provided between telescoping portions to maintain the seal of chamber  20 . 
     Input/output interfaces  48  are linked to chamber inlet  30  and chamber outlet  34 , respectively. Input/output interfaces  48  are positioned on base  62  such that they are in communication with the interior volume of drape  56 . Thus, when drape  56  is in its lowered position that defines an isolated volume, the isolated volume is in gaseous communication with manifold  16  and with gas analyzer  18 . Inlet  30  is also envisioned to have specific ducting to provide that input gas is evenly distributed within chamber  20 . Similarly, outlet  34  is positioned and ducted to maximize the likelihood that gas being sampled is gas that has interacted with test subjects  36  as opposed to coming directly from inlet  30 . 
     In use, a location with an array containing a plurality of lower portions  38  is provided. Test subjects  36  are placed in one or more lower portions  38 . 
     Computer  22  is provided with a plurality of data structures to control system  10  to conduct one or more experiments on test subjects  36 . As noted, lower portions  38  are arranged with a set inter-pot distance  44 . Regardless of the exact layout, computer  22  is provided data that indicates the positioning of the lower portions  38 . The positioning data may be in the form of an existing data file or in the form of user input. Additionally, for any specific experiment run, computer  22  is provided data indicative of which lower portions  38  are in use (that contain a test subjects  36 ). 
     Computer  22  is likewise provided with data structures that contain instructions for movement linkages  46  (and the motors that control them) to cause moveable upper portion  40  to be positioned above each fixed lower portion  38 . 
     Computer  22  accesses the data structure for the experiment protocol to determine which fixed lower portion  38  are in use for the protocol being executed. Similarly, the experiment protocol provides data indicative of what physical/chemical characteristics are provided by each of supply buffers  12 . Computer  22  is provided with data structures that contain instructions for operation of supply pumps  14  and manifold  16  to cause desired gas compositions to be supplied to chamber  20 . 
     Thus, with proper setup of lower portions  38  with test subjects  36  and of supply buffers  14 , an experiment can be developed and carried out with a plurality of similar or different subjects (test subjects  36 ). Computer  22  is provided with a data structure that indicates the particular gas compositions to be supplied to each test subjects  36 . Thus, for “n” test subjects  36 , the experiment protocol provides a treatment to be carried out. 
     Once the experiment protocol data structure is invoked, computer  22  first positions moveable upper portion  40  over the first fixed lower portion  38  and test subjects  36  by emitting signals to instruct movement linkages  46  to move appropriately. Computer  22  then emits instructions to activate motors  50  and unspool cables  54  until interface portion  60  engages interface portion  42 . Computer  22  then emits signals that selectively cause activation of supply pumps  14  and manifold  16  to produce the desired gaseous composition at inlet  30 . As previously noted, the gaseous composition is likewise provided to gas analyzer  18 . Accordingly, to the extent that the signals emitted from computer  22  do not produce an exactly precise gaseous composition, gas analyzer  18  is able to test the composition actually emitting from manifold  16 . 
     Gas analyzer  18  is also testing the gas composition leaving chamber  20  via outlet  34 . By taking successive readings, gas analyzer  18  is able to detect and report to computer  22  changes in gas composition over time. Differences in gas composition between inlet  30  and outlet  34  are presumed to be an artifact of the interaction between the provided gas and test subjects  36 . Furthermore, in that the supplied gas is customizable, system  10  is able to measure the reactions/responses that plants have to changes in the provided atmosphere (gases). System  10  is further able to monitor transient reactions of test subjects  36  (and the resulting changes in output gasses) to the atmospheric changes. In one embodiment where system  10  monitors transient reactions, gas analyzer  18  focuses on readings between when the chamber is able to effect a full chamber air exchange and when the test subjects  36  are able to assume a new gas exchange equilibrium with the new gaseous composition. One such example is to focus on the times between 20 and 70 seconds after a new gas composition is provided to test subjects  36 . In the embodiment, 20 seconds is relevant in that it is the time that the chamber needs to effect an air change within the chamber (3 exchanges per minute=1 change in 20 seconds). Additionally, 70 seconds is relevant in that test subjects  36  are believed to reach a gas exchange equilibrium 50 seconds after application of the new gaseous composition. Once the experiment is completed and the data is gathered, computer  22  emits signals to cause moveable upper portion  40  to move on to a second fixed lower portion  38  and test subjects  36 . 
     To this end, drape  56  is retracted via motors  50 , spools  52 , and cables  54 . Upper portion  40  is then moved above second fixed lower portion  38  and test subjects  36 . Drape  56  is then lowered via motors  50 , spools  52 , and cables  54  such that interface portion  42  engages interface portion  60  of the second fixed lower portion  38 . Again, computer  22  emits instructions to cause activation of supply pumps  14  and manifold  16  to produce the desired gaseous composition at inlet  30 . It should be appreciated that the gas composition supplied to the second fixed lower portion  38  can be the same or different than the gas composition supplied to the first fixed lower portion  38 . 
     Additionally, the gas composition can be changed in the midst of a trial (i.e. the trial may be testing the plant response to going from a first gas composition to a second gas composition). Such gas composition changes include but are not limited to increases/decreases in atmospheric vapor pressure deficit (VPD), temperature, CO 2  concentration, and consecutive changes (raising or lowering) these variables. Furthermore, monitoring output changes relative to the input changes provide transient reaction data. The transient reaction data can provide information about the performance of the test subjects  36  in terms of change in canopy gas exchange capacity, instantaneous water use efficiency in reaction to environmental stimulus, and traits such as drought tolerance, nitrogen use efficiency, tolerance to flood stress, photosynthetic capacity, and any others desired and detectable via the described devices and methods. Additional properties, such as canopy transpiration, transpiration rate, net CO 2  assimilation, CO 2  assimilation rate, net CO 2  assimilation rate, CO 2  concentration, Irradiance, Leaf Stomatal Conductance, and leaf Surface Temperature can also be determined. Accordingly, system  10  provides a high throughput system for screening for traits such as, but not limited to, drought tolerance and nitrogen use efficiency. 
     While this invention has been described as having preferred designs, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this disclosure pertains and which fall within the limits of the appended claims.