Abstract:
The present invention is directed to a robot compatible crystal worksite suite comprising a unique dewar, a plurality of magazines, a plurality of cryo-pins (that mount crystals to be transferred from the dewar for crystallography study) adapted to be placed into the magazines and a programmed controller to provide the operational sequence necessary to remove the frozen mounted crystals from the dewar to an instrument or a goniometer for the x-ray diffraction of the crystals.

Description:
RELATED APPLICATION  
       [0001]    This application is based on provisional application No. 60/350,920, filed Jan. 23, 2002, entitled “Crystal Carrier Magazine System for Use in Crystallography Applications”. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention is directed to a suite of apparatus used in handling crystals for x-ray crystallographic analysis. More specifically, the suite of apparatus includes a unique dewar, a plurality of magazines, a plurality of cryo-pins (that mount crystals to be transferred from the dewar for crystallography study) adapted to be placed into the magazines and a programmed controller to provide the operational sequence necessary to remove the frozen mounted crystals from the dewar to an instrument or a goniometer for the x-ray diffraction of the crystals.  
         BACKGROUND OF THE INVENTION  
         [0003]    U.S. Pat. No. 6,408,047 discloses a method of performing x-ray crystallography on samples by using a robot to transfer the samples to a goniometer. This patent is incorporated herein by reference. The patent discloses the general system that the present invention is directed to but does not disclose a worksite suite as disclosed herein.  
           [0004]    U.S. Pat. No. 6,404,849 discloses a method and apparatus for mounting a crystal sample for x-ray crystallographic analysis. This patent is incorporated herein by reference. The patent discloses the general system that the present invention is directed to but does not disclose a worksite suite as disclosed herein.  
           [0005]    While both patents disclose the general environment of the present invention, the present invention is directed to a worksite suite suitable for use when using a robot to provide the high throughput, automated crystallography methods disclosed in the patents.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention is directed to a robot compatible crystal worksite suite comprising a unique dewar, a plurality of magazines, a plurality of cryo-pins (that mount crystals to be transferred from the dewar for crystallography study) adapted to be placed into the magazines and a programmed controller to provide the operational sequence necessary to remove the frozen mounted crystals from the dewar to an instrument or a goniometer for the x-ray diffraction of the crystals. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a magazine of the present invention;  
         [0008]    [0008]FIG. 2 is an exploded view of a magazine of the present invention;  
         [0009]    [0009]FIG. 3 is a top view of a magazine of the present invention;  
         [0010]    [0010]FIG. 4 is a cross-sectional view of a magazine of the present invention along line  4 - 4  of FIG. 3;  
         [0011]    [0011]FIG. 5 is a top view of a magazine tongs that is part of the worksite suite of the present invention;  
         [0012]    [0012]FIG. 6 is a side view of the magazine tongs in FIG. 5;  
         [0013]    [0013]FIG. 7 is a shipping rack that holds five magazines of the present invention;  
         [0014]    [0014]FIG. 8 is a worksite dewar;  
         [0015]    [0015]FIG. 9 is a partial cross-section of the dewar;  
         [0016]    [0016]FIG. 10 is the dewar with a programmed controller;  
         [0017]    [0017]FIG. 11 is a top view of the worksite dewar that has no magazines inside;  
         [0018]    [0018]FIG. 12 is a top view of the worksite dewar that has five (5) magazines inside; and  
         [0019]    [0019]FIG. 13 is a cryo-pin tongs that removes cryo-pins from a magazine manually and is part of the worksite suite of the present invention. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0020]    The central component of the suite of apparatus of the present invention used in handling crystals for x-ray crystallographic analysis is a multi-position magazine. The magazine is used for precisely locating, protecting and transferring batches of crystals that require cryogenic storage and handling. The magazine  10  is constructed from two parts, as shown in FIG. 1 and FIG. 2. The top part  12  of magazine  10  has a plurality of cylinders  14 , specifically shown are twelve ( 12 ) cylinders; however the exact number may vary. The cylinders  14  are held by an outer member  15  that is essentially configured as a circle. The lower part  16  of magazine  10  has the same number of location bosses  18  as cylinders  14  that are positioned to be centered in the corresponding cylinder. In each location boss  18  is a magnet  20 . The strong magnets  20  are held in place with epoxy to hold the cryo-pin  30 , a product of Hampton Research having a ferrous base  34  (see FIG. 4), securely on the location bosses  18 . The magnets  20  also hold the magazine  10  securely on a ferrous work surface during crystal manipulation. The upper part  12  and lower part  16  of magazine  10  are held together with epoxy and pressed spring pins  24 . Referring now to FIG. 3, the outer member  15  conforms to surface of the cylinders  14  to provide guides  17  the gross location of the magazine  10 . On one surface of outer member  15 , a member  19  is in a form to provide tabs  21  for the forceps grasping tool  40  and a slot  23  for a locking pin, described hereinafter.  
         [0021]    The magazine  10  described in FIGS.  1 - 4  provides a device for protecting and transferring twelve crystals each mounted on a cryo-pin  30 . The cryo-pins  30 , that hold the frozen crystals, are seated in the cylinders  14  of the magazine  10  as shown in FIG. 4. The cylinders  14  hold liquid nitrogen and keep the cryo-pins  30  submerged in the liquid nitrogen while the magazine  10  is transfer from one dewar to another. The cylinders  14  also protect the crystals and pins  30 , which are held to the boss  18  on the bottom part  16  of the magazine  10  by the magnets  20 .  
         [0022]    The magazine  10  is handled using a grasping tool or magazine tongs  40  that utilize a “dumbbell” shaped tip  42  attached to the end of forceps  44  (FIGS. 5 and 6). The tips  42  grasp the magazine  10  via slotted tabs  21  at the top edge of the magazine  10 , as shown in FIG. 3. Since the magazine  10  is typically submerged in liquid nitrogen, the magazine tongs  40  allow the user to remove the magazine from one dewar to another. The typical dewar of the prior art has a rack with a number of rack plates each spaced by threaded standoff members. The rack  50  shown in FIG. 7 is designed to be compatible with the magazines  10  and the suite of the present invention thus having six plates  52 . The plates  52  are made from martensitic stainless steel that allows the magazine  10  to be held in place by the magnets  20 . The threaded standoff members  54  are configured to provide the spacing between plates  52  to place a magazine  10  on each plate  52  and provide a guide for the gross location of the magazine  10  on the plate  52 . A retaining bar  56  fits in slot  23  of magazines  10  (FIG. 3) to securely hold the magazine  10  on the plate  52 . The retaining bar  56  is held in position by passing through holes in plates  52  and secured by a magnet  58 . A support rod  59  is attachable to the top plate  52  to place the five magazines into or remove the magazines from a dewar.  
         [0023]    Reference is made to U.S. Pat. Nos. 6,408,047 and 6,494,849, both of which are directed to providing a method of performing x-ray crystallography on samples using a robot or robotic arm. The magazines  10  of the present invention are specially suited and compatible to be used in such a system. The worksite suite of the present invention provides for high volume of crystal samples to be tested while lessening the need for human intervention.  
         [0024]    Another central component of the worksite suite of the present invention is the worksite dewar  60 . Now referring to FIG. 8, the worksite dewar  60  provides a staging area for the crystallography system. The dewar  60  is placed in a mounting fixture  62  that is precisely calibrated with the robotic arm of a robot system. A condensation catch pan  64  is at the bottom of the dewar  60 . The dewar  60  has a lid  66 . The dewar is a double wall flask  68  with a vacuum between inner wall  67  and outer wall  69 . The flask  68  is capable of holding liquid nitrogen. On the outside of the flask  68  is insulation  70 . At the upper portion of the flask  68  is a rim insulator  72 . A heater  75  is mounted to the rim  77  to heat the rim  77  but is insulated from the flask  68 . The heater  75  minimizes condensation on the rim and prevents the freezing of any condensation that does form on the rim  77  that would prevent the lid  66  from opening.  
         [0025]    Referring to FIG. 10, the worksite dewar lid actuator assembly  65 , is connected to a programmable controller  80  that may be separate from or part of the robot system. The actuator assembly  65  is comprised of a commercial linear actuator attached to the outboard end of the lid hinge  67 , beyond the lid hinge pin. The actuator assembly  65  also includes micro switches which provide interlocks for both robot and dewar lid operation. When part of the robot system, the controller  80  will open the lid  66  before the robotic arm enters the dewar  60  to remove or return a crystal to a magazine in the dewar  60 . As shown in FIGS. 11 and 12, the worksite dewar  60  holds five magazines  10 . The floor of flask  68  has a precision mounting plate  81  which has twenty alignment pins  82 , four for each magazine for the course alignment of a magazine  10  and ten alignment pins  84  for the fine alignment of each magazine  10 . The dewar  60  has a liquid cryogen, liquid nitrogen, inlet  88  on the side of the dewar  60 . As shown in FIG. 12, five magazines  10  are placed in the working dewar  60 , containing a total of sixty samples of crystals to be tested by x-ray crystallography.  
         [0026]    Pin tongs  90  are part of the suite of the present invention since there are occasions when the cryo-pins  30  are handled manually.