An effective and rapid forming device and method for staples

Abstract

The invention discloses an effective and rapid forming device and method for anastomotic staples, comprising: firstly designing a hydrophobic surface imitating a cicada wing, then performing a hydrophobic treatment, and subsequently covering the surface with a hard coating, adjusting a titanium wire through a rotating adjustment device therein so that the hydrophobic surface imitating a cicada wing of the titanium wire is always facing downwards and finally reaches the position of a staple making device, because the existence of the hard coating protects the hydrophobic surface imitating a cicada wing from being destroyed, and finally forming a U-shaped anastomotic staple with the hydrophobic surface imitating a cicada wing facing inwards; arranging a design of the hydrophobic surface imitating a cicada wing to ensure correct positioning, utilizing visual sensing technology and a rotating adjustment mechanism to ensure that the titanium wire always maintains a correct orientation during the staple making process, so that the hydrophobic surface imitating a cicada wing is located on the inner side of a U-shaped groove; and improving the corrosion resistance and antibacterial ability of the anastomotic staple by treating the titanium wire, and effectively reducing the risk of infection.

Description

Technical Field

[0001] The invention relates to the field of medical devices, and in particular to an effective and rapid forming device and method for anastomotic staples. Background Art

[0002] With the development of society and the continuous improvement of people's living standards, the medical industry has developed rapidly. Doctors have changed the way of suturing human tissues or organs from manual suturing with needles and threads to suturing with medical staplers and alloy staples. The use of medical staplers for suturing is easy to operate, safe and causes little trauma, and has been accepted by the majority of surgical clinicians; common staplers are made of titanium wire, which is widely used due to its excellent mechanical properties and biocompatibility, especially in the fields of aerospace, medical equipment, etc.

[0003] In gastrointestinal tumor diseases, gastrointestinal surgery is required, and staplers are the most commonly used medical devices. However, since staples are prone to tissue inflammation during use, staples made of titanium wires need to be treated in a certain way. In addition, during the process of making staples from titanium wires, some surface structures of the titanium wires are easily damaged, which affects the effect of staple implantation. Summary of the invention

[0004] The present invention overcomes the shortcomings of the prior art and provides an effective and rapid forming device and method for anastomotic staples.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: an effective and rapid forming device and method for staples, comprising: a titanium wire with a microstructure and a protective layer on the surface;

[0006] The nail making device comprises a working table, a rotating adjustment device installed on the working table, two first and second placement seats installed on the working table, a lower forming block installed at the center of the second placement seat, a bending pressure head installed on the first placement seat opposite to the lower forming block, a lower pressure head also installed on the first placement seat, and two cutting knives symmetrically installed on the second placement seat; the bending pressure head is provided with a forming groove, and the lower forming block is provided with a forming protrusion corresponding to the forming groove;

[0007] The rotary adjustment device 4 is used to adjust the angle of the titanium wire, including a support frame, a small turntable 41 rotatably connected to the support frame, a motor connected to the outer edge of the small turntable 41 through a transmission belt, a second clamp 42 and a visual sensor installed on the small turntable 41; the small turntable 41 is provided with a circular groove for the titanium wire to pass through;

[0008] The stepping conveyor belt is used for smoothly conveying the titanium wire to the nail making device.

[0009] In a preferred embodiment of the present invention, the microstructure is a surface hydrophobic structure imitating a cicada wing.

[0010] In a preferred embodiment of the present invention, the visual sensor has a multi-spectral imaging function, which can accurately locate the surface hydrophobic structure imitating cicada wings by identifying the difference in reflectivity of different materials.

[0011] In a preferred embodiment of the present invention, the molded protrusion is an arc-shaped protrusion.

[0012] In a preferred embodiment of the present invention, the protective layer is a hard coating, and the hard coating is polytetrafluoroethylene.

[0013] In a preferred embodiment of the present invention, the rotation adjustment device further includes an angle feedback unit, and the angle feedback unit is used to monitor the angle change of the turntable in real time.

[0014] In a preferred embodiment of the present invention, the second clamp comprises a pair of adjustable jaws, and an elastic buffer layer is provided inside each of the jaws.

[0015] In a preferred embodiment of the present invention, the small turntable can rotate 360 ​​degrees.

[0016] An effective and rapid forming method for staples.

[0017] S51, the stepping conveyor belt conveys the titanium wire to the working area of ​​the rotary adjustment device;

[0018] S52, fixing the titanium wire with a second fixture, and identifying the position of the cicada wing-like hydrophobic structure on the upper surface of the titanium wire by a visual sensor;

[0019] S53, rotating the adjustment device to adjust the angle of the titanium wire to ensure that the cicada wing-like hydrophobic treatment surface is always facing downward;

[0020] S54, conveying the adjusted titanium wire along the stepping conveyor belt to the working processing table of the nail making device;

[0021] S55, placing the titanium wire between the first placement seat and the second placement seat, starting the bending pressure head, and cooperating with the lower forming block to bend the titanium wire into a U-shaped structure.

[0022] The present invention solves the defects existing in the background technology and has the following beneficial effects:

[0023] (1) By setting a rotating adjustment device, the titanium wire is adjusted so that the cicada wing-like hydrophobic surface of the titanium wire is always facing downward and finally reaches the position of the nail making device. Because of the presence of the hard coating, the protection of the cicada wing-like hydrophobic surface is destroyed, and finally a U-shaped anastomotic staple with the cicada wing-like hydrophobic surface facing inward is made; the corrosion resistance and antibacterial ability of the titanium wire are significantly enhanced by the design of the cicada wing-like hydrophobic surface, and correct positioning is ensured. The visual sensing technology and the rotating adjustment mechanism are used to ensure that the titanium wire always maintains the correct orientation during the nail making process, so that the cicada wing-like hydrophobic surface is located on the inner side of the U-shaped groove; compared with the existing technology, the surface of the titanium wire with special surface treatment is adjusted during stamping, which reduces the damage to the titanium wire surface during stamping and avoids affecting the effect of the titanium wire after implantation. By treating the cicada wing-like hydrophobic surface of the titanium wire, the corrosion resistance and antibacterial ability of the anastomotic staple are improved, and the risk of infection is effectively reduced during preparation. The anastomotic staple is stamped with the cicada wing-like hydrophobic surface facing downward.

[0024] (2) The rotary adjustment device is a key component to ensure that the titanium wire always maintains the correct orientation during the nailing process. The small turntable driven by the motor can accurately control the angle change of the titanium wire to ensure that the cicada wing-like hydrophobic surface is always facing down and located inside the U-shaped groove. The multi-spectral imaging function of the visual sensor enables the system to identify the difference in reflectivity of different materials, accurately locate the cicada wing-like treatment area, and guide the clamping device to automatically adjust the angle of the titanium wire. The angle feedback unit monitors the angle change of the turntable in real time to ensure the accuracy of each adjustment; this automated adjustment mechanism greatly improves production efficiency, reduces errors caused by manual intervention, and ensures the consistency and high quality of each staple; in addition, the use of an elastic buffer layer reduces the pressure on the titanium wire surface during the clamping process, avoids damage caused by excessive clamping, and further protects the effect of the cicada wing-like hydrophobic treatment; compared with the existing technology, the rotary adjustment device ensures the structure of the titanium wire surface and enhances the stability and reliability of production.

[0025] (3) The formed protrusion is set to be an arc-shaped protrusion; the position of the arc-shaped protrusion is in contact with the hydrophobic surface of the cicada wing of the titanium wire, thereby reducing the damage caused by the edge of the protrusion to the hydrophobic surface of the cicada wing, and the arc-shaped protrusion reduces the local stress on the surface of the titanium wire; compared with the existing technology, the damage to the structure of the stapler is reduced, and the integrity of the surface structure of the stapler is maintained.

[0026] (4) The design of the hydrophobic surface imitating the cicada wing creates a microstructure on the surface of the titanium wire, imitating the hydrophobic properties of cicada wings in nature, giving the titanium wire unique physical properties; this design significantly enhances the hydrophobicity and self-cleaning ability of the titanium wire, making its surface less susceptible to water and other contaminants, which not only reduces the chance of bacteria and microorganisms attaching, reducing the risk of infection during surgery, but also improves the corrosion resistance of the titanium wire. Due to its low friction coefficient and self-lubricating properties, this design helps to reduce the friction between the titanium wire and surrounding tissues or instruments, thereby reducing the risk of mechanical damage during surgical operations. In addition, the cicada wing-like structure can effectively prevent blood or other body fluids from condensing on its surface, further improving biocompatibility. This design provides multiple protections for titanium wire, ensuring its safety and effectiveness in medical applications.

[0027] (5) The application of hard coating provides an additional protective barrier for titanium wire, significantly enhancing its wear resistance and corrosion resistance; polytetrafluoroethylene (PTFE) or ceramic is selected as the coating material. These materials themselves have extremely high chemical stability and mechanical strength, which can effectively prevent the cicada wing hydrophobic treatment on the surface of titanium wire from being destroyed during the stamping process; the low friction coefficient and self-lubricating properties of the hard coating not only reduce the wear during stamping, but also reduce the friction between the titanium wire and the mold, making the molding process smoother and reducing equipment loss; in addition, the excellent anti-adhesion performance of the coating material ensures that the titanium wire will not have unnecessary adhesion with other substances during the processing process, maintaining the cleanliness of the surface; the presence of hard coating prolongs the service life of titanium wire, improves the durability and reliability of the product, and is particularly suitable for medical devices that need to be implanted in the human body for a long time; compared with the existing technology, the application of hard coating not only improves the physical properties of titanium wire, but also provides reliable guarantee for its application in complex medical environments, ensuring the high quality and safety of the final product. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 It is a schematic diagram of the overall working of the present invention;

[0030] Figure 2 is a front view of the nail making device of the present invention;

[0031] Figure 3 is a front view of the rotation adjustment device of the present invention;

[0032] In the figure: 4, rotating adjustment device; 40, supporting frame; 41, small turntable; 42, second clamp; 43, motor; 5, nail making device; 51, working processing table; 52, first placement seat; 53, second placement seat; 54, lower forming block; 55, bending pressure head; 56, lower pressure head; 57, cutting knife. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0035] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application 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 limiting the scope of protection of the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention, unless otherwise specified, "multiple" means two or more.

[0036] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0037] The surface microstructure of the titanium wire is treated to be a cicada-wing-like hydrophobic structure, and its structure has unique microscopic and nanoscale structures, which give it excellent hydrophobicity and self-cleaning ability.

[0038] The specific preparation method of the surface hydrophobic structure imitating cicada wings is as follows:

[0039] S11. Perform preliminary treatments such as cleaning and degreasing on the titanium wire to ensure that the surface is clean and free of pollution

[0040] S12. Place the titanium wire on the workbench and use a clamp to firmly grasp the titanium wire to ensure that it remains stable during processing;

[0041] S13, according to the required cicada wing-like texture size parameters: W1: 30μm x 30μm), set the power of the industrial-grade laser to 10W-50W, the scanning speed to 100mm / s to 500mm / s, and the pulse frequency to 1kHz-10kHz;

[0042] S14, start the laser and XY motion platform, scan the surface of the titanium wire point by point according to the preset path, and form a cicada wing-like texture of a predetermined size. The laser beam is focused on the surface of the titanium wire to create a microstructure by melting and evaporating the material; after the processing is completed, the cooling device is immediately started to quickly cool the titanium wire to prevent damage caused by thermal stress.

[0043] The method for making the titanium wire surface hydrophobic after the preliminary microstructure is as follows:

[0044] S21, sequentially placing the titanium wire into a tank of stearic acid ethanol solution with different concentrations to give it hydrophobic properties;

[0045] S22. After soaking, use an ultrasonic cleaner to thoroughly remove the residual solution to ensure surface cleanliness.

[0046] It should also be noted that the protective layer on the surface of the titanium wire is a hard coating, and the hard coating is polytetrafluoroethylene; the specific method of adding the hard coating is:

[0047] S31. Use a high-voltage electrostatic spray gun or a rotary atomizer. The distance between the nozzle and the titanium wire should be kept between 15cm and 30cm to ensure uniform coating distribution.

[0048] S32. The angle between the nozzle and the titanium wire surface should be maintained between 45° and 90° to ensure that the coating can fully cover the entire surface; the spraying speed is 0.5m / s to 2m / s, the spraying pressure is controlled between 0.3MPa and 0.8MPa, and 3 to 6 sprayings are performed, and the final coating thickness is 10μm to 50μm;

[0049] After a series of treatments are performed on the titanium wire, the hard coating on the surface of the titanium wire is stripped. The specific stripping process is as follows:

[0050] S41. Clean the titanium wire and ensure that the surface is free of oil and other impurities; immerse the titanium wire in a container filled with a mild chemical stripper (using a 1% to 5% sodium citrate solution) for 30 minutes;

[0051] S42. During the soaking process, an ultrasonic cleaning machine is used to assist in enhancing the effect of the chemical stripper and promoting the removal of the coating;

[0052] S43, stirring the solution every 5 minutes to ensure that the chemical stripping agent acts evenly on the entire titanium wire surface;

[0053] S44. Check the coating removal using a high-resolution microscope or electron microscope and extend the immersion time if necessary;

[0054] S45. Take out the titanium wire and rinse it thoroughly with plenty of deionized water to remove the residual chemical stripper; use a hot air gun to dry it quickly.

[0055] like Figure 1 As shown, an effective and rapid forming device and method for staples, comprising: a titanium wire, with a microstructure and a protective layer on the surface;

[0056] The nail making device 5 comprises a working table 51, a rotating adjustment device 4 installed on the working table 51, two first placement seats 52 and second placement seats 53 installed on the working table 51, which are arranged opposite to each other, a lower forming block 54 installed at the center of the second placement seat 53, a bending press head 55 installed on the first placement seat 52 and opposite to the lower forming block 54, a lower press head 56 is also installed on the first placement seat 52, and two cutters 57 are symmetrically installed on the second placement seat 53; the bending press head 55 is provided with a forming groove, and the lower forming block 54 is provided with a forming protrusion corresponding to the forming groove;

[0057] The rotary adjustment device 4 is used to adjust the angle of the titanium wire, including a support frame, a small turntable 41 rotatably connected to the support frame, a motor connected to the outer edge of the small turntable 41 through a transmission belt, a second clamp 42 and a visual sensor installed on the small turntable 41; the small turntable 41 is provided with a circular groove for the titanium wire to pass through;

[0058] The stepping conveyor belt is used to smoothly convey the titanium wire to the nail making device 5.

[0059] like Figure 2As shown, specifically, in the nail making device 5, the forming groove in the bending press head 55 is a U-shaped groove, and the groove angle in the U-shaped groove is arc-shaped; the stress on the surface of the titanium wire during the stamping process is reduced, and the damage to the surface of the titanium wire during the stamping process is reduced.

[0060] Furthermore, the visual sensor has a multi-spectral imaging function, which can accurately locate the hydrophobic treatment area of ​​the cicada wing by identifying the difference in reflectivity of different materials.

[0061] Specifically, for the visual sensor to identify the surface hydrophobic structure of cicada wings, its specific identification process is:

[0062] The visual sensor uses a multi-wavelength light source (the light source is visible light (400nm to 700nm), near infrared (700nm to 1400nm) and mid-infrared (1400nm to 3000nm)) to sequentially illuminate the surface of the titanium wire and record the reflection image at each wavelength;

[0063] Preprocess the collected images, including noise removal, grayscale processing and normalization;

[0064] According to the reflection images at each wavelength, the cicada wing structure and the surrounding substrate are distinguished, and the reflectivity of each pixel on the titanium wire surface is calculated:

[0065]

[0066] Where R(λ) is the reflectivity at wavelength λ, I reflected (λ) is the reflected light intensity, I incident (λ) is the incident light intensity;

[0067] Use the edge detection algorithm (Canny operator) to identify the edge contour of the cicada wing structure:

[0068] I smooth =G*I,

[0069] Where G is the Gaussian filter, I is the input image, and I smooth is the smoothed image;

[0070] The surface hydrophobic structure imitating cicada wings is identified by identifying reflectivity and edge contour.

[0071] like Figure 2 As shown, further, a placement area for placing titanium wire is formed between the two cutters 57 and the lower forming block 54.

[0072] Furthermore, the rotation adjustment device also includes an angle feedback unit, and the angle feedback unit is used to monitor the angle change of the turntable in real time.

[0073] like Figure 3As shown, specifically, in the rotation adjustment device, a motor is also provided on the support frame and connected to the small turntable 41 through a transmission belt, so as to adjust the angle of the titanium wire; the motor can accurately control the rotation speed and angle of the small turntable 41, and the small turntable 41 can rotate 360°, and the second clamp 42 includes a pair of adjustable claws, each of which is provided with an elastic buffer layer inside, which is used to fix the titanium wire and allow the titanium wire to move when the turntable rotates; the visual sensor is arranged relative to the second clamp 42, and has a multi-spectral imaging function, which can identify the difference in reflectivity of different materials and accurately locate the hydrophobic treatment area of ​​the cicada wing imitation, and is also provided with an angle feedback unit, which can monitor the angle change of the turntable in real time to ensure the adjustment accuracy.

[0074] It can ensure that the titanium wire always maintains the correct orientation during the nail making process, so that the cicada wing-like hydrophobic surface is located on the inner side of the U-shaped groove, thereby improving production efficiency and product quality, reducing manual intervention, and ensuring the consistency of each anastomotic staple.

[0075] Furthermore, the second clamp 42 includes a pair of adjustable claws, and an elastic buffer layer is provided inside each claw.

[0076] Furthermore, the small turntable 41 can rotate 360°.

[0077] An effective and rapid forming method for staples;

[0078] S51, the stepping conveyor belt conveys the titanium wire to the working area of ​​the rotary adjustment device;

[0079] S52, fixing the titanium wire with a second fixture, and identifying the position of the cicada wing-like hydrophobic structure on the upper surface of the titanium wire by a visual sensor;

[0080] S53, rotating the adjustment device to adjust the angle of the titanium wire to ensure that the cicada wing-like hydrophobic treatment surface is always facing downward;

[0081] S54, conveying the adjusted titanium wire along the stepping conveyor belt to the working processing table of the nail making device;

[0082] S55, placing the titanium wire between the first placement seat and the second placement seat, starting the bending pressure head, and cooperating with the lower forming block to bend the titanium wire into a U-shaped structure.

[0083] It should be added that the conveying speed of the stepping conveyor belt is 0.5m / min to 2m / min, the pressure between the bending pressure head 64 and the lower forming block 65 is set to 10MPa to 50MPa, and the forming speed is controlled at 1 time / s to 3 times / s.

[0084] Through the design of the cicada wing-like hydrophobic surface, the corrosion resistance and antibacterial ability of the titanium wire are significantly enhanced to ensure correct positioning. The visual sensing technology and the rotation adjustment mechanism are used to ensure that the titanium wire always maintains the correct orientation during the nail making process, so that the cicada wing-like hydrophobic surface is located on the inside of the U-shaped groove.

[0085] When the present invention is used, the stepping conveyor belt is started to smoothly convey the titanium wire to the rotating adjustment device 4, the cicada wing-like hydrophobic surface on the titanium wire is identified by the visual sensor, the position of the cicada wing-like hydrophobic surface is accurately located, and the clamping device is guided to automatically adjust the angle of the titanium wire to ensure that the cicada wing-like hydrophobic surface is always facing downward, and the titanium wire is placed between two oppositely arranged first placement seats 52 and second placement seats 53, and the bending pressure head 55 is started to cooperate with the lower forming block 54 to accurately bend the titanium wire into a U-shaped structure.

[0086] The above is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. An effective and rapid forming device for staples, characterized in that: include: Titanium wire, with microstructure and protective layer on the surface; The nail making device (5) comprises a working table (51), a rotating adjustment device (4) installed on the working table (51), two first placement seats (52) and a second placement seat (53) installed on the working table (51) and arranged opposite to each other, a lower forming block (54) installed at the center of the second placement seat (53), a bending press head (55) installed on the first placement seat (52) and opposite to the lower forming block (54), a lower press head (56) is also installed on the first placement seat (52), and two cutters (57) are also symmetrically installed on the second placement seat (53); the bending press head (55) is provided with a forming groove, and the lower forming block (54) is provided with a forming protrusion corresponding to the forming groove; A rotary adjustment device (4) for adjusting the angle of the titanium wire comprises a support frame, a small turntable (41) rotatably connected to the support frame, a motor connected to the outer edge of the small turntable (41) via a transmission belt, a second clamp (42) and a visual sensor installed on the small turntable (41); the small turntable (41) is provided with a circular groove for the titanium wire to pass through; The stepping conveyor belt is used to smoothly convey the titanium wire to the nail making device (5).

2. The effective and rapid forming device for staples according to claim 1, characterized in that: The microstructure is a surface hydrophobic structure imitating a cicada wing.

3. The effective and rapid forming device for staples according to claim 1, characterized in that: The visual sensor has a multi-spectral imaging function, which can accurately locate the surface hydrophobic structure of cicada wings by identifying the difference in reflectivity of different materials.

4. The effective and rapid forming device for staples according to claim 1, characterized in that: The molding protrusion is an arc-shaped protrusion.

5. The effective and rapid forming device for staples according to claim 1, characterized in that: The protective layer is a hard coating, and the hard coating is polytetrafluoroethylene.

6. The effective and rapid forming device for staples according to claim 1, characterized in that: The rotation adjustment device also includes an angle feedback unit, which is used to monitor the angle change of the turntable in real time.

7. The effective and rapid forming device for staples according to claim 1, characterized in that: The second clamp (42) comprises a pair of adjustable jaws, each of which has an elastic buffer layer inside.

8. The effective and rapid forming device for staples according to claim 1, characterized in that: A placement area for placing titanium wire is formed between the two cutting knives (57) and the lower forming block (54).

9. The apparatus for efficiently and quickly forming staples and the method for efficiently and quickly forming staples according to claim 1 are characterized by: S51, the stepping conveyor belt conveys the titanium wire to the working area of ​​the rotary adjustment device; S52, fixing the titanium wire with a second fixture, and identifying the position of the cicada wing-like hydrophobic structure on the upper surface of the titanium wire by a visual sensor; S53, rotating the adjustment device to adjust the angle of the titanium wire to ensure that the cicada wing-like hydrophobic treatment surface is always facing downward; S54, conveying the adjusted titanium wire along the stepping conveyor belt to the working processing table of the nail making device; S55, placing the titanium wire between the first placement seat and the second placement seat, starting the bending pressure head, and cooperating with the lower forming block to bend the titanium wire into a U-shaped structure.

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