Equipment for monitoring wall breaking effect of plant in real time by using low-temperature plasma

Abstract

The invention discloses equipment for monitoring the wall breaking effect of plants in real time through low-temperature plasmas. The equipment comprises a shell assembly, a bearing assembly arranged at the top of the shell assembly, a top cover assembly arranged at the top of the bearing assembly and a filtering assembly arranged in the top cover assembly. According to the device for monitoring the wall breaking effect of the plants in real time through the low-temperature plasma, the plant wall breaking device is arranged, the crushing assembly is arranged in the plant wall breaking device, the wall breaking effect is effectively guaranteed, the plasma discharging assembly is arranged on the side face of the crushing assembly, and the plasma discharging assembly can generate plasmas and make the plasmas directly make contact with the plants subjected to wall breaking; according to the wall breaking technology for chemical bond action of substances, natural plants are efficiently broken, active components in cells are promoted to be dissolved out, the utilization efficiency of the natural plants is improved, secondly, a monitoring structure is arranged, the states of the plants before and after wall breaking can be checked, the structure does not need to be opened, monitoring is effectively guaranteed, and diffusion and loss of plasmas are avoided.

Description

Technical Field

[0001] This invention relates to the field of plant cell wall disruption technology, specifically to a device for real-time monitoring of plant cell wall disruption effects using low-temperature plasma. Background Technology

[0002] Low-temperature plasma is a high-energy aggregated state of matter containing a large number of active particles such as electrons, ions, excited-state atoms, molecules, photons, and free radicals.

[0003] Energy transfer in low-temperature plasma generally proceeds as follows: electrons gain energy from the electric field, converting this energy into the internal and kinetic energy of molecules through collisions. The energized molecules are excited, and simultaneously, some molecules are ionized. These activated particles collide with each other, triggering a series of complex physicochemical reactions. The abundance of active particles within plasma, such as ions, electrons, excited atoms and molecules, and free radicals, provides the conditions for plasma technology to treat odorous substances through chemical reactions. It is an interdisciplinary field based on discharge physics, discharge chemistry, and reaction engineering.

[0004] In recent decades, research on plasma technology has been very active, providing new technologies, methods, and processes for the synthesis of new substances and materials, as well as for environmental pollution control. Low-temperature plasma degradation of pollutants utilizes these high-energy electrons, free radicals, and other active particles to interact with pollutants in waste gas, causing the pollutant molecules to decompose in a very short time and undergo various subsequent reactions to achieve the purpose of pollutant degradation. However, regardless of the high-voltage discharge technology used, the principle of high-voltage discharge necessitates careful consideration of explosion risks, especially in flammable and explosive chemical environments.

[0005] Vacuum ultraviolet plasma cell disruption technology is also used in the market. Its principle is to break the chemical bonds on the cell surface through the action of VUV, thereby producing surface modification and causing the cell wall to rupture in a short time.

[0006] In existing technologies, mechanical disruption is the primary method for breaking down plant cell walls. However, the lack of effective plasma coordination during the disruption process prevents efficient cell wall disruption and hinders the release of active components from the cells, thus reducing the utilization efficiency of these natural plants. Furthermore, it is difficult to inspect the state before and after disruption after the process is complete, and opening the structure can affect the internal environment. Summary of the Invention

[0007] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0008] 1. Technical problems to be solved:

[0009] To address the issues mentioned above, such as the lack of effective plasma coordination during the cell wall disruption process, which hinders efficient cell wall disruption and makes it difficult to dissolve active components from cells, thus reducing the utilization efficiency of these natural plants, and the difficulty in inspecting the state before and after disruption after the process, which would affect the internal environment when the structure needs to be opened, this invention was proposed.

[0010] Therefore, the purpose of this invention is to provide a device for real-time monitoring of plant cell wall disruption using low-temperature plasma. The device includes a cell wall disruption unit with an internal breaking component to effectively ensure the disruption effect. The breaking component has a plasma discharge component on its side, which generates plasma and brings it into direct contact with the disrupted plant cells. This cell wall disruption process, which breaks down the chemical bonds of substances, is highly efficient for natural plants, promoting the dissolution of active components in the cells and improving the utilization efficiency of these natural plants. A monitoring structure is included to check the state of the plant before and after cell wall disruption without opening the structure, effectively ensuring monitoring and preventing plasma diffusion and loss.

[0011] 2. Technical Solution:

[0012] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution:

[0013] A device for real-time monitoring of plant cell wall disruption effect by low-temperature plasma includes a shell assembly, a support assembly disposed on top of the shell assembly, a top cover assembly disposed on top of the support assembly, and a filter assembly disposed inside the top cover assembly.

[0014] in:

[0015] A housing assembly, the housing assembly including a base and a housing disposed on top of the base;

[0016] The support assembly includes a support plate, and the top of the support plate is sequentially provided with a monitoring head for easy observation of the inside of the shell, a crushing assembly for easy breaking of the material inside the shell, and a plasma discharge assembly for easy contact between ejected plasma and the material.

[0017] A top cover assembly, the top cover assembly including a top cover shell, an air inlet disposed on the side wall of the top cover shell and communicating with the plasma discharge assembly, and a control panel electrically connected to the monitoring head, the crushing assembly, the plasma discharge assembly and the filter assembly;

[0018] A filter assembly, one end of which is connected to the plasma discharge assembly and the other end of which is connected to the air inlet.

[0019] As a preferred embodiment of the device for real-time monitoring of plant cell wall breaking effect by low-temperature plasma according to the present invention, the top cover assembly further includes a display screen electrically connected in series with the monitoring head, and the display screen is snapped to the side wall of the top cover shell.

[0020] As a preferred embodiment of the device for real-time monitoring of plant cell wall breaking effect by low-temperature plasma according to the present invention, the breaking component includes a motor embedded in the top of the support plate, a rotating rod disposed at the output end of the motor, and breaking blades arranged at equal intervals on the outer circumference of the rotating rod.

[0021] As a preferred embodiment of the device for real-time monitoring of plant cell wall breaking effect by low-temperature plasma according to the present invention, the plasma discharge component includes a blocking medium, a low-pressure electrode disposed on the outer surface of the blocking medium, and a high-pressure electrode disposed on the inner surface of the blocking medium. A plasma discharge region is formed between the low-pressure electrode and the high-pressure electrode. The blocking medium forms a cavity, one end of which is connected to the air inlet, and the other end of which is connected to the nozzle.

[0022] As a preferred embodiment of the device for real-time monitoring of plant cell wall breaking effect by low-temperature plasma according to the present invention, the bottom of the top cover shell is provided with a sealing rubber ring, the top of the top cover shell is provided with a handrail, and the monitoring head, the motor and the plasma discharge assembly are all disposed inside the top cover shell.

[0023] As a preferred embodiment of the device for real-time monitoring of plant cell wall breaking effect by low-temperature plasma according to the present invention, the filter assembly includes a connecting cap disposed at the bottom, a connecting pipe threadedly connected to the bottom of the connecting cap, a flexible tube threadedly connected to the bottom of the connecting pipe, and the end of the flexible tube being sleeved with the top of the plasma discharge assembly.

[0024] As a preferred embodiment of the device for real-time monitoring of plant cell wall breaking effect by low-temperature plasma according to the present invention, the filter assembly includes an air pump disposed on the side wall, and the input end of the air pump is connected to the air inlet.

[0025] As a preferred embodiment of the device for real-time monitoring of plant cell wall breaking effect by low-temperature plasma according to the present invention, the control panel includes multiple independent buttons, each of which is provided with a wire that can be independently electrically connected.

[0026] As a preferred embodiment of the device for real-time monitoring of plant cell wall breaking effect by low-temperature plasma according to the present invention, the bottom of the support plate is provided with a sealing rubber ring, the support plate is sleeved on the top of the shell through the sealing rubber ring, and an arc-shaped wrench is adhered to the outer circumference of the support plate.

[0027] As a preferred embodiment of the device for real-time monitoring of plant cell wall breaking effect by low-temperature plasma according to the present invention, the side wall of the housing is provided with a handle, and the side wall of the handle is fitted with a rubber sleeve.

[0028] 3. Beneficial effects:

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] This device for real-time monitoring of plant cell wall breaking effects using low-temperature plasma, through the combined use of accessories, is equipped with a plant cell wall breaking device. Its internal crushing component effectively ensures the cell wall breaking effect. The side of the crushing component has a plasma discharge component, which generates plasma and brings it into direct contact with the broken plant. This cell wall breaking process, which breaks the chemical bonds of substances, is highly efficient in breaking the cell walls of natural plants, promoting the dissolution of active components in the cells and improving the utilization efficiency of these natural plants.

[0031] This device for real-time monitoring of plant cell wall disruption using low-temperature plasma, through the combination of accessories, is equipped with a monitoring structure that allows for inspection of the plant's state before and after cell wall disruption without opening the structure, effectively ensuring monitoring while preventing plasma diffusion and loss. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0033] Figure 1 This is a schematic diagram of the overall structure of a device for real-time monitoring of plant cell wall disruption effects using low-temperature plasma according to the present invention.

[0034] Figure 2 This is a side view of the device for real-time monitoring of plant cell wall disruption effect using low-temperature plasma according to the present invention.

[0035] Figure 3 This is a schematic diagram of the supporting components and the top cover components of a device for real-time monitoring of plant cell wall disruption effects using low-temperature plasma according to the present invention.

[0036] Figure 4 This is a schematic diagram of the plasma discharge component of a device for real-time monitoring of plant cell wall disruption effects using low-temperature plasma, according to the present invention.

[0037] Figure 5 This is a schematic cross-sectional view of the plasma discharge component of a device for real-time monitoring of plant cell wall disruption effects using low-temperature plasma, according to the present invention.

[0038] Figure 6 This is a schematic diagram of the filter component of a device for real-time monitoring of plant cell wall disruption effects using low-temperature plasma, according to the present invention.

[0039] The following are the labeling instructions in the diagram: 100, outer casing assembly; 110, base; 120, housing; 130, handle; 200, load-bearing assembly; 210, load-bearing plate; 220, monitoring head; 221, display screen; 230, crushing assembly; 231, motor; 232, rotating rod; 233, crushing blade; 240, plasma discharge assembly; 241, low-pressure electrode; 242, high-pressure electrode; 243, plasma discharge area; 244, blocking medium; 245, nozzle; 300, top cover assembly; 310, top cover shell; 320, air inlet; 400, filter assembly; 410, connecting cap; 420, connecting pipe; 430, air pump. Detailed Implementation

[0040] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0041] This invention is described in detail with reference to the schematic diagrams. When describing the embodiments of this invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not be construed as limiting the scope of protection of this invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0042] The orientation or positional relationship indicated in the terminology is based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing the invention and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0043] The term "connection method" should be interpreted broadly. For example, "connection" 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 a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] The embodiments of the present invention will now be described in further detail with reference to the accompanying drawings.

[0045] This invention provides a schematic diagram of the overall structure of an embodiment of a device for real-time monitoring of plant cell wall disruption effects using low-temperature plasma, comprising:

[0046] Please see Figures 1-6 This embodiment of a device for real-time monitoring of plant cell wall breaking effect by low-temperature plasma includes a shell assembly 100, a support assembly 200 disposed on the top of the shell assembly 100, a top cover assembly 300 disposed on the top of the support assembly 200, and a filter assembly 400 disposed inside the top cover assembly 300.

[0047] in:

[0048] The housing assembly 100 includes a base 110 and a housing 120 disposed on top of the base 110. The base 110 is made of composite material and the bottom can be provided with resistance grooves to make the base 110 more stable in the position where it is needed. The housing 120 is a metal housing. The overall depth of the housing assembly 100 is pre-adjusted according to the actual situation.

[0049] The support assembly 200 includes a support plate 210. The top of the support plate 210 is sequentially provided with a monitoring head 220 for easy observation of the interior of the housing 120. The monitoring head 220 can be a commonly available model. The support assembly 230 is used to break up the material inside the housing 120. The support assembly 240 is used to make the ejected plasma come into contact with the material. The breaking assembly 230 is located at the center point of the housing assembly 100 to facilitate the most uniform breaking effect. Multiple holes are opened on the top of the support plate 210 to facilitate the entry of the monitoring head 220, the motor 231 and the plasma discharge assembly 240. To ensure stability, small sealing structures are provided in these holes to ensure a sealing and stable effect.

[0050] The top cover assembly 300 includes a top cover shell 310, which can be made of composite plastic material. It is integrally molded and has an air inlet 320 on the side wall of the top cover shell 310 and connected to the plasma discharge assembly 240. The size of the air inlet 320 can be adjusted according to the actual situation. A mesh cover is glued to the outside of the air inlet 320 to prevent impurities from entering the interior and the control panel of the electrical connection monitoring head 220, the crushing assembly 230, the plasma discharge assembly 240 and the filter assembly 400. The model of the control panel can be a commonly used model on the market.

[0051] One end of the filter assembly 400 is connected to the plasma discharge assembly 240, and the other end is connected to the air inlet 320. The filter assembly 400 has an internal filtration structure, such as glass fiber filter cotton, activated carbon filter cotton, synthetic fiber filter cotton, and non-woven filter cotton. Glass fiber filter cotton is made of glass fibers of various thicknesses and lengths through a special processing technology. It has the characteristics of high temperature resistance, high efficiency, large capacity, and long service life, and is widely used in places and environments with high air filtration requirements. Activated carbon filter cotton is mainly used to remove odors and harmful substances from the air. It is usually used in conjunction with other filters to improve the overall filtration effect. Synthetic fiber filter cotton is an emerging filter material with the advantages of low resistance, light weight, large capacity, and environmental friendliness. It is suitable for general filtration environments. Non-woven filter cotton, scientifically known as polyester fiber, has the characteristics of wide application, mature technology, and good stability. It is suitable for primary and medium-efficiency filters and has the advantages of stable quality, large dust holding capacity, strong moisture resistance, and long service life.

[0052] It is worth noting that, in order to facilitate monitoring and display, the top cover assembly 300 also includes a display screen 221 electrically connected in series with the monitoring head 220, and the display screen 221 is snapped to the side wall of the top cover shell 310.

[0053] Next, to facilitate the crushing of plants, the crushing component 230 specifically includes a motor 231 embedded in the top of the support plate 210, a rotating rod 232 disposed at the output end of the motor 231, and crushing blades 233 arranged at equal intervals on the outer circumference of the rotating rod 232. The output end of the motor 231 is connected to the rotating rod 232 through a coupling. The outer circumference of the rotating rod 232 is assembled with the crushing blades 233 by welding. The number and size of the crushing blades 233 can be adjusted according to actual needs.

[0054] Meanwhile, to facilitate plasma generation, the plasma discharge assembly 240 is specifically cylindrical in shape. The plasma discharge assembly 240 includes a barrier medium 244, a low-pressure electrode 241 disposed on the outer surface of the barrier medium 244, and a high-pressure electrode 242 disposed on the inner surface of the barrier medium 244. A plasma discharge region 243 is formed between the low-pressure electrode 241 and the high-pressure electrode 242. The barrier medium 244 forms a cavity, with one end connected to an air inlet 320 and the other end connected to a nozzle 245. The low-pressure electrode 241 and the high-pressure electrode 242 are respectively connected to a high-voltage power supply via power lines. The low-pressure electrode 241 and the high-pressure electrode 242 are separated by the barrier medium 244. This part is prior art, and embodiments in the prior art can be referred to.

[0055] Furthermore, to increase overall sealing and ensure the safety of the plant cell wall breaking process, specifically, a sealing rubber ring is provided at the bottom of the top cover shell 310, a handrail is provided at the top of the top cover shell 310, and the monitoring head 220, motor 231 and plasma discharge assembly 240 are all located inside the top cover shell 310.

[0056] It is worth noting that, in order to ensure the stability of the connection, the filter assembly 400 specifically includes a connecting cap 410 at the bottom, a connecting tube 420 threadedly connected to the bottom of the connecting cap 410, a flexible tube threadedly connected to the bottom of the connecting tube 420, and the end of the flexible tube being sleeved on the top of the plasma discharge assembly 240.

[0057] Subsequently, in order to ensure the air intake effect, specifically, the filter assembly 400 includes an air pump 430 installed on the side wall. The input end of the air pump 430 is connected to the air inlet 320. The model of the air pump 430 can be a commonly used model on the market.

[0058] Next, in order to facilitate independent control of multiple structures, the control panel includes multiple independent buttons, each of which is equipped with a wire that can be electrically connected independently.

[0059] It is worth noting that, in order to increase the sealing performance and facilitate hand operation when opening, a sealing rubber ring is provided at the bottom of the support plate 210. The support plate 210 is fitted onto the top of the housing 120 through the sealing rubber ring, and an arc-shaped wrench is attached to the outer circumference of the support plate 210.

[0060] Finally, to facilitate handling and prevent slippage, a handle 130 is provided on the side wall of the housing 120, and a rubber sleeve is fitted onto the side wall of the handle 130.

[0061] In addition, the circuits, electronic components and modules involved in this invention are all existing technologies, which can be fully implemented by those skilled in the art, and need not be elaborated upon. The content protected by this invention does not involve any improvement to the internal structure and method.

[0062] Combination Figures 1-6 The specific usage process of the device for real-time monitoring of plant cell wall disruption effect by low-temperature plasma according to this embodiment is as follows:

[0063] 1. Place the plant in the housing 120 of the outer casing assembly 100 and place the base 110 stably in a suitable area. The side of the housing 120 is also provided with a handle 130 for easy handling. At this time, cover the support plate 210 to seal the housing 120.

[0064] 2. Then, the crushing assembly 230 is turned on. During the movement of the motor 231 in the crushing assembly 230, it will drive the rotating rod 232. During the rotation of the rotating rod 232, it will drive the crushing blade 233 on the rotating rod 232, so that the crushing blade 233 cuts and breaks the plant. During this process, the monitoring head 220 on the support plate 210 can transmit the image to the display screen 221 of the top cover shell 310 in real time. At the same time, a plasma discharge assembly 240 is also provided on the side of the crushing assembly 230.

[0065] 3. The plasma discharge assembly 240 has a cavity formed by a barrier medium 244, including a low-voltage electrode 241, a high-voltage electrode 242, and a plasma discharge region 243. The barrier medium 244 must be made of insulating material. Therefore, the reactor structure is similar to that of a capacitor. To achieve discharge, alternating current must be applied to both sides of the electrode. Direct current cannot pass through. At the same time, the electric field strength must be high enough to cause gas breakdown. The material of the barrier medium 244 includes, but is not limited to, glass, quartz glass, ceramics, and enamel. This part is prior art.

[0066] 4. Finally, when the plant is broken, the plasma discharge component 240 generates plasma and brings it into direct contact with the broken plant. This cell-breaking process, which breaks down the chemical bonds of the material, is highly efficient in breaking down the cell walls of natural plants, promoting the dissolution of active components in the cells and improving the utilization efficiency of these natural plants.

[0067] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the features in the disclosed embodiments can be combined with each other in any manner. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A device for real-time monitoring of plant cell wall disruption effects using low-temperature plasma, characterized in that, It includes a housing assembly (100), a support assembly (200) disposed on top of the housing assembly (100), a top cover assembly (300) disposed on top of the support assembly (200), and a filter assembly (400) disposed inside the top cover assembly (300); in: A housing assembly (100) includes a base (110) and a housing (120) disposed on top of the base (110); The support assembly (200) includes a support plate (210), and the top of the support plate (210) is sequentially provided with a monitoring head (220) for easy observation of the inside of the shell (120), a crushing assembly (230) for easy breaking of the material inside the shell (120), and a plasma discharge assembly (240) for easy contact between ejected plasma and the material. Top cover assembly (300), the top cover assembly (300) includes a top cover shell (310), an air inlet (320) disposed on the side wall of the top cover shell (310) and communicating with the plasma discharge assembly (240), and a control panel electrically connected to the monitoring head (220), the crushing assembly (230), the plasma discharge assembly (240) and the filter assembly (400); A filter assembly (400) is provided, one end of which is connected to the plasma discharge assembly (240), and the other end of which is connected to the air inlet (320).

2. The device for real-time monitoring of plant cell wall disruption effect using low-temperature plasma according to claim 1, characterized in that, The top cover assembly (300) also includes a display screen (221) electrically connected in series with the monitoring head (220), the display screen (221) being snap-fitted to the side wall of the top cover shell (310).

3. The device for real-time monitoring of plant cell wall disruption effect using low-temperature plasma according to claim 1, characterized in that, The crushing assembly (230) includes a motor (231) embedded in the top of the support plate (210), a rotating rod (232) disposed at the output end of the motor (231), and crushing blades (233) arranged at equal intervals on the outer circumference of the rotating rod (232).

4. The device for real-time monitoring of plant cell wall disruption effect using low-temperature plasma according to claim 1, characterized in that, The plasma discharge assembly (240) includes a barrier medium (244), a low-pressure electrode (241) disposed on the outer surface of the barrier medium (244), and a high-pressure electrode (242) disposed on the inner surface of the barrier medium (244). A plasma discharge region (243) is formed between the low-pressure electrode (241) and the high-pressure electrode (242). The barrier medium (244) forms a cavity. One end of the cavity is connected to the air inlet (320), and the other end of the cavity is connected to the nozzle (245).

5. The device for real-time monitoring of plant cell wall disruption effect using low-temperature plasma according to claim 3, characterized in that, The bottom of the top cover (310) is provided with a sealing rubber ring, and the top of the top cover (310) is provided with a handrail. The monitoring head (220), the motor (231) and the plasma discharge assembly (240) are all located inside the top cover (310).

6. The device for real-time monitoring of plant cell wall disruption effect using low-temperature plasma according to claim 1, characterized in that, The filter assembly (400) includes a connecting cap (410) disposed at the bottom, the bottom of the connecting cap (410) being threadedly connected to a connecting tube (420), the bottom of the connecting tube (420) being threadedly connected to a flexible tube, the end of the flexible tube being sleeved on the top of the plasma discharge assembly (240).

7. The device for real-time monitoring of plant cell wall disruption effect using low-temperature plasma according to claim 4, characterized in that, The filter assembly (400) includes an air pump (430) disposed on the side wall, the input end of which is connected to the air inlet (320).

8. The device for real-time monitoring of plant cell wall disruption effect using low-temperature plasma according to claim 1, characterized in that, The control panel includes multiple independent buttons, each of which is equipped with a wire that can be electrically connected independently.

9. The device for real-time monitoring of plant cell wall disruption effect using low-temperature plasma according to claim 1, characterized in that, A sealing rubber ring is provided at the bottom of the support plate (210), and the support plate (210) is sleeved on the top of the housing (120) through the sealing rubber ring. An arc-shaped wrench is glued to the outer circumference of the support plate (210).

10. The device for real-time monitoring of plant cell wall disruption effect using low-temperature plasma according to claim 1, characterized in that, The side wall of the housing (120) is provided with a handle (130), and the side wall of the handle (130) is fitted with a rubber sleeve.

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