Automatic Gas Sampling and Vacuum Pumping System for Gas Chromatograph

Abstract

The present invention relates to the technical field of gas chromatograph equipment, specifically an automatic gas sampling and vacuum pumping system for a gas chromatograph, including: a base, on the upper surface of the base is placed a gas cylinder tray, and on the upper surface of the gas cylinder tray are provided a plurality of gas cylinder placement holes distributed in a rectangular array; above the cross beam is provided a Y-axis screw rod driven to rotate by a Y-axis motor; a plurality of positioning grooves correspond one-to-one with the plurality of gas cylinder placement holes in the Y-axis direction, and a strip-shaped plate passes through the through groove from bottom to top and is fixedly connected to the cross beam; a Y-axis slider is threadedly sleeved on the Y-axis screw rod; The beneficial effects are: by fixedly inserting a strip-shaped plate from bottom to top in the middle of the cross beam, a sliding component is slidably installed on the upper surface of the cross beam, and the adjustment slider can slide a certain distance between the two Y-axis sliders. The sliding control of the sliding component of this device is simpler, and the positioning accuracy of the adjustment slider is higher.

Description

Technical Field

[0001] The present invention relates to the technical field of gas chromatograph equipment, and specifically to an automatic gas injection and vacuum pumping system for a gas chromatograph. Background Art

[0002] A gas chromatograph is an instrument that uses chromatographic separation technology and detection technology to qualitatively and quantitatively analyze complex mixtures of multiple components. During the use of a gas chromatograph, it is necessary to extract the gas from the gas cylinder sample.

[0003] The main working mode of an automatic gas injector for a gas chromatograph is to fix the position of the needle, place the gas sample bottles in a spiral arrangement on a circular tray, rotate and move the circular tray to send the gas sample bottles below the needle, and then vertically move the needle to pierce into the gas sample bottles to supply gas to the gas chromatograph.

[0004] However, currently, due to the spiral arrangement of the gas sample bottles, during the rotation and movement of the circular tray, the positioning accuracy is low, the control is complex, and the gas sample bottles are easily damaged. Therefore, the present invention proposes an automatic gas injection and vacuum pumping system for a gas chromatograph to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide an automatic gas injection and vacuum pumping system for a gas chromatograph to solve the problems of complex control and low positioning accuracy during the rotation and movement of the circular tray as mentioned in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solution: An automatic gas injection and vacuum pumping system for a gas chromatograph, including:

[0007] A base, on the upper surface of which a gas cylinder tray is placed, and a plurality of gas cylinder placement holes are arranged in a rectangular array on the upper surface of the gas cylinder tray;

[0008] A gantry, which is slidably connected to the base along the X-axis direction of the base. The upper end of the gantry is fixedly connected with a cross beam, and a through groove is formed through the middle of the cross beam. Above the cross beam, a Y-axis screw rod driven by a Y-axis motor to rotate is arranged, and the Y-axis screw rod is rotatably connected to the gantry;

[0009] A strip-shaped plate, on the upper surface of which a plurality of positioning grooves are arranged at equal intervals, and the plurality of positioning grooves correspond to the plurality of gas cylinder placement holes in the Y-axis direction one by one. The strip-shaped plate passes through the through groove from bottom to top and is fixedly connected to the cross beam; and

[0010] A sliding assembly is slidably installed on the outside of the Y-axis screw and fits into the upper surface of the crossbeam. The sliding assembly includes an adjusting slider and a Y-axis slider located on both sides of the adjusting slider. An adjusting spring is provided between the Y-axis slider and the adjusting slider. The Y-axis slider is threadedly connected to the Y-axis screw, and a positioning ball is provided on the lower surface of the adjusting slider that is compatible with the positioning groove.

[0011] Preferably, a circular hole is provided in the middle of the adjusting slider and is movably sleeved on the Y-axis screw. The edge of the open end of the circular hole is chamfered. A threaded ring is fixedly connected to the side of the Y-axis slider away from the adjusting slider, and the threaded ring is threadedly connected to the Y-axis screw. An annular groove is provided on the side of the Y-axis slider close to the adjusting slider, and the end of the adjusting spring is fixedly embedded in the bottom of the annular groove.

[0012] Preferably, the lower surface of the adjusting slider is in contact with the upper surface of the strip plate, and the lower surface of the Y-axis slider is provided with a sliding groove, and the sliding groove is stuck on the outer side of the upper surface of the strip plate.

[0013] Preferably, a receiving groove is provided on the lower surface of the adjusting slider, a thrust spring is provided in the inner cavity of the receiving groove, the upper part of the positioning ball is located in the inner cavity of the receiving groove and is pressed by the thrust spring, and a protrusion is fixedly connected to the side of the adjusting slider.

[0014] Preferably, the surface of the protrusion is fixedly connected to a vertical plate by bolts, the lower end of the vertical plate is fixedly connected to the bottom block, the middle part of the vertical plate is fixedly connected to the Z-axis motor, the output end of the Z-axis motor is fixedly connected to the Z-axis screw, and the Z-axis screw and the bottom block are rotatably connected through a bearing.

[0015] Preferably, the outer side of the Z-axis screw is threadedly sleeved with a Z-axis slider, the side of the Z-axis slider is fixedly connected to a needle mounting bracket, a guide slot is provided in the middle of the needle mounting bracket, the side of the bottom block is fixedly connected to a guide block slidably connected to the guide slot, and the lower end of the needle mounting bracket is equipped with a vacuum needle.

[0016] Preferably, a strip-shaped card plate is fixedly connected to the front of the vertical plate, and a card slot is provided on the back of the Z-axis slider. The card slot is clamped on the outside of the strip-shaped card plate and is slidably connected thereto.

[0017] Preferably, a hollow groove is opened inside the base, the lower end of the gantry is slidably installed in the inner cavity of the hollow groove, an X-axis screw driven by an X-axis motor is rotatably installed in the middle of the inner cavity of the hollow groove, an X-axis slider is fixedly connected to the middle of the lower end of the gantry, and the X-axis slider and the X-axis screw are threadedly connected.

[0018] Preferably, guide rods are fixedly connected to both sides of the inner cavity of the hollow groove. Guide sliding holes are formed on both sides of the lower end of the gantry, and the guide sliding holes are movably sleeved on the outer sides of the guide rods.

[0019] Preferably, an installation groove is formed on the upper surface of the base, and the gas cylinder tray is placed in the installation groove by gravity to maintain positioning.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] In the present invention, a strip-shaped plate is fixedly inserted from bottom to top in the middle of the cross beam. A sliding assembly is slidably installed on the upper surface of the cross beam. The sliding assembly includes an adjustment slider and Y-axis sliders on both sides of the adjustment slider. An adjustment spring is provided between the Y-axis sliders and the sliding assembly. The Y-axis sliders are driven by Y-axis screws to slide and drive the adjustment slider to slide. A positioning ball is arranged on the lower surface of the adjustment slider for engaging with the positioning groove on the surface of the strip-shaped plate. The adjustment slider can slide a certain distance between the two Y-axis sliders to prevent the air extraction needle installed on one side of the adjustment slider from being misaligned with the gas cylinder sample placed in the gas cylinder placement hole due to the excessive or too small sliding distance of the Y-axis slider. Compared with the traditional rotation movement of the circular tray, the sliding control of the sliding assembly of this device is simpler, and the positioning accuracy of the adjustment slider is higher. Description of the Drawings

[0022] Figure 1 is a three-dimensional schematic diagram of the overall structure of the present invention;

[0023] Figure 2 is a semi-sectional schematic diagram of the base structure of the present invention;

[0024] Figure 3 is a three-dimensional schematic diagram of the gantry structure of the present invention;

[0025] Figure 4 is an installation schematic diagram of the air extraction needle structure of the present invention;

[0026] Figure 5 is an exploded schematic diagram of the sliding assembly structure of the present invention;

[0027] Figure 6 is an exploded schematic diagram of the adjustment slider structure of the present invention.

[0028] In the figure: 1, base; 2, gas cylinder tray; 3, gas cylinder placement hole; 4, gantry; 40, X-axis slider; 41, guiding sliding hole; 5, cross beam; 6, Y-axis screw rod; 61, Y-axis motor; 7, through slot; 8, strip plate; 9, positioning groove; 10, sliding assembly; 11, Y-axis slider; 12, adjusting slider; 13, round hole; 14, adjusting spring; 15, positioning ball; 18, air extraction needle head; 19, Z-axis motor; 20, convex block; 21, vertical plate; 22, bottom block; 23, Z-axis screw rod; 24, Z-axis slider; 25, needle head mounting rack; 26, guiding sliding groove; 27, guiding block; 28, strip clamping plate; 29, clamping slot; 30, storage groove; 31, thrust spring; 32, chamfer; 33, sliding groove; 34, threaded collar; 35, annular groove; 36, hollow groove; 37, X-axis screw rod; 38, X-axis motor; 39, guiding rod. Detailed implementation manners

[0029] In order to clearly and completely describe the objectives, technical solutions of the present invention and make the advantages more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are some but not all of the embodiments of the present invention, and are only used to explain the embodiments of the present invention, rather than to limit the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0030] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "middle", "upper", "lower", "left", "right", "inner", "outer", "top", "bottom", "side", "vertical", "horizontal", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention. In addition, the terms "one", "first", "second", "third", "fourth", "fifth", "sixth" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0031] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0032] For the purposes of simplicity and illustration, the principles of the embodiments are mainly described by reference to examples. In the following description, many specific details are set forth in order to provide a thorough understanding of the embodiments. It is apparent, however, to one of ordinary skill in the art that the embodiments may not be limited to these specific details in practice. In some instances, well-known methods and structures are not described in detail so as not to unnecessarily obscure the embodiments. Additionally, all embodiments may be used in combination with each other.

[0033] Please refer to Figures 1 to 6 , the present invention provides a technical solution:

[0034] Embodiment 1

[0035] An automatic gas sampling and vacuum pumping system for a gas chromatograph, comprising: a base 1, a gantry 4, a strip plate 8 and a sliding assembly 10.

[0036] Specifically, a gas cylinder tray 2 is placed on the upper surface of the base 1, and a plurality of gas cylinder placement holes 3 arranged in a rectangular array are formed on the upper surface of the gas cylinder tray 2 for plugging and placing gas cylinder samples;

[0037] Secondly, the gantry 4 is slidably connected to the base 1 in the X-axis direction of the base 1. The gantry 4 is slidable. The upper half of the gantry 4 is located above the base 1. A cross beam 5 is fixedly connected to the upper end of the gantry 4, and a through groove 7 is formed through the middle of the cross beam 5. A Y-axis screw rod 6 driven to rotate by a Y-axis motor 61 is arranged above the cross beam 5, and the Y-axis screw rod 6 is rotatably connected to the gantry 4. Therefore, when the Y-axis motor 61 operates, it can drive the Y-axis screw rod 6 to rotate;

[0038] Furthermore, a plurality of positioning grooves 9 arranged at equal intervals are formed on the upper surface of the strip plate 8, and the plurality of positioning grooves 9 correspond to the plurality of gas cylinder placement holes 3 in the Y-axis direction one by one. The strip plate 8 passes through the through groove 7 from bottom to top and is fixedly connected to the cross beam 5. The strip plate 8 is fixed by bolts and can be disassembled to replace and select positioning grooves 9 with different spacings;

[0039] In addition, the sliding assembly 10 is slidably mounted outside the Y-axis screw rod 6 and is in contact with the upper surface of the cross beam 5. The sliding assembly 10 includes an adjustment slider 12 and Y-axis sliders 11 located on both sides of the adjustment slider 12. An adjustment spring 14 is provided between the Y-axis sliders 11 and the adjustment slider 12. The Y-axis sliders 11 are threadedly sleeved on the Y-axis screw rod 6. A positioning ball 15 adapted to the positioning groove 9 is provided on the lower surface of the adjustment slider 12. When the Y-axis screw rod 6 rotates, it drives the Y-axis sliders 11 to slide along the length direction of the Y-axis screw rod 6 through bolts, thereby driving the adjustment slider 12 to move. However, since there is a gap between the adjustment slider 12 and the Y-axis sliders 11 and the adjustment spring 14 is provided, after the positioning ball 15 on the lower surface of the adjustment slider 12 is engaged with the positioning groove 9, the adjustment slider 12 can be accurately positioned to prevent the adjustment slider 12 from being unable to maintain a correct correspondence with the positioning groove 9 due to the Y-axis sliders 11 sliding too far or too little. When the Y-axis sliders 11 continue to move, the elastic force provided by the adjustment spring 14 pushes the adjustment slider 12 to continue sliding, so as to correspond to the next positioning groove 9.

[0040] Embodiment Two

[0041] On the basis of Embodiment One, in order to prevent the adjustment slider 12 from being stuck by the thread on the surface of the Y-axis screw rod 6 when sliding, the present application further has a circular hole 13 opened in the middle of the adjustment slider 12 and movably sleeved on the Y-axis screw rod 6. A chamfer 32 is provided at the edge of the open end of the circular hole 13 to prevent the adjustment slider 12 from being stuck by the thread on the surface of the Y-axis screw rod 6 when sliding. A threaded collar 34 is fixedly connected to the side surface of the Y-axis slider 11 away from the adjustment slider 12, and the threaded collar 34 is screwed onto the Y-axis screw rod 6. An annular groove 35 is opened on the side surface of the Y-axis slider 11 close to the adjustment slider 12, and the end of the adjustment spring 14 is fixedly embedded at the bottom of the annular groove 35 to facilitate the fixation of the adjustment spring 14.

[0042] Embodiment Three

[0043] On the basis of Embodiment Two, in order to prevent the Y-axis slider 11 from being laterally deflected along the X-axis, the lower surface of the adjustment slider 12 of the present application is in contact with the upper surface of the strip plate 8. A sliding groove 33 is opened on the lower surface of the Y-axis slider 11, and the sliding groove 33 is stuck on the outer side of the upper surface of the strip plate 8 to ensure that the Y-axis slider 11 will not be laterally deflected along the X-axis.

[0044] Embodiment Four

[0045] On the basis of Embodiment III, in order to separate the positioning ball 15 from the positioning groove 9, the present application further has a receiving groove 30 formed on the lower surface of the adjusting slider 12. A thrust spring 31 is arranged in the inner cavity of the receiving groove 30. The upper part of the positioning ball 15 is located in the inner cavity of the receiving groove 30 and is pressed by the thrust spring 31. A convex block 20 is fixedly connected to the side surface of the adjusting slider 12. Therefore, the positioning ball 15 can also be received into the inner cavity of the receiving groove 30 to be separated from the positioning groove 9.

[0046] Embodiment V

[0047] On the basis of Embodiment IV, the present application further has a vertical plate 21 fixedly connected to the surface of the convex block 20 by bolts. A bottom block 22 is fixedly connected to the lower end of the vertical plate 21. A Z-axis motor 19 is fixedly connected to the middle of the vertical plate 21. An output end of the Z-axis motor 19 is fixedly connected to a Z-axis screw rod 23. The Z-axis screw rod 23 is rotatably connected to the bottom block 22 through a bearing, as Figure 4 shown. When the Z-axis motor 19 works, it can drive the Z-axis screw rod 23 to rotate.

[0048] Embodiment VI

[0049] On the basis of Embodiment V, in order to adjust the height of the air extraction needle 18, the present application further has a Z-axis slider 24 threadedly sleeved on the outside of the Z-axis screw rod 23. A needle mounting frame 25 is fixedly connected to the side surface of the Z-axis slider 24. A guiding chute 26 is formed in the middle of the needle mounting frame 25. A guiding block 27 slidably connected to the guiding chute 26 is fixedly connected to the side surface of the bottom block 22. An air extraction needle 18 is installed at the lower end of the needle mounting frame 25. Therefore, when the Z-axis screw rod 23 rotates, it can drive the Z-axis slider 24 to slide up and down along the Z-axis direction to adjust the height position of the air extraction needle 18.

[0050] Embodiment VII

[0051] On the basis of Embodiment VI, in order to prevent the Z-axis slider 24 from being laterally deflected along the Y-axis direction, the present application further has a strip-shaped clamping plate 28 fixedly connected to the front surface of the vertical plate 21. A clamping groove 29 is formed on the back surface of the Z-axis slider 24. The clamping groove 29 is stuck on the outside of the strip-shaped clamping plate 28 and is slidably connected thereto to prevent the Z-axis slider 24 from being laterally deflected along the Y-axis direction.

[0052] Embodiment VIII

[0053] On the basis of Embodiment VII, in order to drive the gantry 4 to slide in the X-axis direction, the present application further has a hollow groove 36 opened inside the base 1. The lower end of the gantry 4 is slidably installed in the inner cavity of the hollow groove 36. In the middle of the inner cavity of the hollow groove 36, an X-axis screw 37 driven to rotate by an X-axis motor 38 is rotatably installed. The middle of the lower end of the gantry 4 is fixedly connected with an X-axis slider 40. The X-axis slider 40 is threadedly sleeved with the X-axis screw 37. Therefore, when the X-axis motor 38 works, the cooperation of the X-axis screw 37 and the X-axis slider 40 can drive the gantry 4 to slide in the X-axis direction.

[0054] Embodiment IX

[0055] On the basis of Embodiment VIII, in order to guide the sliding of the gantry 4, the present application further has guide rods 39 fixedly connected to both sides of the inner cavity of the hollow groove 36. Guide sliding holes 41 are opened on both sides of the lower end of the gantry 4. The guide sliding holes 41 are movably sleeved on the outer sides of the guide rods 39. The cooperation of the guide rods 39 and the guide sliding holes 41 is used to guide the sliding of the gantry 4 to prevent the gantry 4 from tilting or deviating laterally.

[0056] Embodiment X

[0057] On the basis of Embodiment IX, in order to facilitate the replacement of the gas cylinder tray 2, the present application further has an installation groove opened on the upper surface of the base 1. The gas cylinder tray 2 is placed in the installation groove by gravity to maintain positioning, so as to facilitate the replacement of the gas cylinder tray 2.

[0058] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Automatic gas sampling and vacuum pumping system for gas chromatograph, characterized in that: Comprising: A base (1), on the upper surface of the base (1) is placed a gas cylinder tray (2), and on the upper surface of the gas cylinder tray (2) are provided a plurality of gas cylinder placement holes (3) distributed in a rectangular array; A gantry (4), the gantry (4) is slidably connected to the base (1) along the X-axis direction of the base (1), the upper end of the gantry (4) is fixedly connected with a cross beam (5), and a through groove (7) is formed through the middle of the cross beam (5). Above the cross beam (5) is provided a Y-axis screw rod (6) driven to rotate by a Y-axis motor (61), and the Y-axis screw rod (6) is rotatably connected to the gantry (4); A strip plate (8), on the upper surface of the strip plate (8) are provided a plurality of positioning grooves (9) distributed at equal intervals, and the plurality of positioning grooves (9) correspond to the plurality of gas cylinder placement holes (3) in the Y-axis direction one by one. The strip plate (8) passes through the through groove (7) from bottom to top and is fixedly connected to the cross beam (5); and A sliding assembly (10), the sliding assembly (10) is slidably installed on the outer side of the Y-axis screw rod (6) and fits with the upper surface of the cross beam (5). The sliding assembly (10) includes an adjusting slider (12) and Y-axis sliders (11) located on both sides of the adjusting slider (12). An adjusting spring (14) is arranged between the Y-axis slider (11) and the adjusting slider (12). The Y-axis slider (11) is threadedly sleeved on the Y-axis screw rod (6), and a positioning ball (15) adapted to the positioning groove (9) is arranged on the lower surface of the adjusting slider (12); A circular hole (13) is formed through the middle of the adjusting slider (12) and is movably sleeved on the Y-axis screw rod (6). A chamfer (32) is formed at the edge of the open end of the circular hole (13). A threaded collar (34) is fixedly connected to the side surface of the Y-axis slider (11) away from the adjusting slider (12), and the threaded collar (34) is screwed on the Y-axis screw rod (6). An annular groove (35) is formed on the side surface of the Y-axis slider (11) close to the adjusting slider (12), and the end of the adjusting spring (14) is fixedly embedded at the bottom of the annular groove (35).

2. The automatic gas sampling and vacuum pumping system for a gas chromatograph according to claim 1, wherein: The lower surface of the adjusting slider (12) fits with the upper surface of the strip plate (8). A sliding groove (33) is formed on the lower surface of the Y-axis slider (11), and the sliding groove (33) is stuck on the outer side of the upper surface of the strip plate (8).

3. The automatic gas sampling and vacuum pumping system for a gas chromatograph according to claim 2, characterized in that: A receiving groove (30) is formed on the lower surface of the adjusting slider (12). A thrust spring (31) is arranged in the inner cavity of the receiving groove (30). The upper part of the positioning ball (15) is located in the inner cavity of the receiving groove (30) and is pressed by the thrust spring (31). A convex block (20) is fixedly connected to the side surface of the adjusting slider (12).

4. The automatic gas sampling and vacuum pumping system for a gas chromatograph according to claim 3, characterized in that: A vertical plate (21) is fixedly connected to the surface of the convex block (20) by bolts. A bottom block (22) is fixedly connected to the lower end of the vertical plate (21). A Z-axis motor (19) is fixedly connected to the middle of the vertical plate (21). An output end of the Z-axis motor (19) is fixedly connected with a Z-axis screw rod (23), and the Z-axis screw rod (23) is rotatably connected to the bottom block (22) through a bearing.

5. The automatic gas sampling and vacuum pumping system for a gas chromatograph according to claim 4, characterized in that: The outer thread of the Z-axis screw rod (23) is sleeved with a Z-axis slider (24). The side of the Z-axis slider (24) is fixedly connected with a needle mounting bracket (25). A guiding sliding groove (26) is formed in the middle of the needle mounting bracket (25). The side of the bottom block (22) is fixedly connected with a guiding block (27) which is slidably connected with the guiding sliding groove (26). A gas extraction needle (18) is installed at the lower end of the needle mounting bracket (25).

6. The automatic gas sampling and vacuum pumping system for a gas chromatograph according to claim 5, characterized in that: The front of the vertical plate (21) is fixedly connected with a strip-shaped clamping plate (28). A clamping groove (29) is formed in the back of the Z-axis slider (24). The clamping groove (29) is clamped outside the strip-shaped clamping plate (28) and is slidably connected with it.

7. The automatic gas sampling and vacuum pumping system for a gas chromatograph according to claim 6, wherein: A hollow groove (36) is formed inside the base (1). The lower end of the gantry (4) is slidably installed in the inner cavity of the hollow groove (36). An X-axis screw rod (37) driven by an X-axis motor (38) to rotate is rotatably installed in the middle of the inner cavity of the hollow groove (36). The middle of the lower end of the gantry (4) is fixedly connected with an X-axis slider (40). The X-axis slider (40) is threadedly sleeved with the X-axis screw rod (37).

8. The automatic gas sampling and vacuum pumping system for a gas chromatograph according to claim 7, characterized in that: Guide rods (39) are fixedly connected to both sides of the inner cavity of the hollow groove (36). Guide sliding holes (41) are formed in both sides of the lower end of the gantry (4). The guide sliding holes (41) are movably sleeved outside the guide rods (39).

9. The automatic gas sampling and vacuum pumping system for a gas chromatograph according to claim 8, wherein: An installation groove is formed on the upper surface of the base (1). The gas cylinder tray (2) is placed in the installation groove by gravity to maintain positioning.

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