46results about How to "Guaranteed bonding" patented technology

The invention belongs to the technical field of fabrics, and particularly relates to a modified ultra-high molecular weight polyethylene stab-resistant fiber and a preparation method thereof. The preparation method comprises the following steps: 1) adding mesoporous WO3 and surface hydroxylated BN into ethanol for ultrasonic dispersion, adding water and stirring to obtain WO3-BN; 2) mixing the WO3-BN with the PTFE suspension, adding a silane coupling agent, and stirring to obtain a modified nano composite material; and 3) putting ultra-high molecular weight polyethylene, the modified nano composite material and an antioxidant into a double-screw extruder for melting, mixing, conveying and shearing, carrying out melt spinning extrusion and water bath cooling to obtain nascent fibers, and carrying out three-stage hot stretching and winding to obtain the modified ultra-high molecular weight polyethylene stab-resistant fibers. The prepared modified ultra-high molecular weight polyethylene puncture-proof fiber has excellent tensile strength, tensile modulus, cutting resistance and puncture-proof performance.

The present invention relates to a mine plugging method and structure thereof, which uses roughening and grooving of cave walls, brickwork, temporary water diversion, clay filling, and concrete plugging of wellheads to plug the mine. The present invention sets a clay filling section before the concrete plugging section, and performs interval grooving around the cave wall of the set clay filling section, which can ensure that the filled clay is completely combined with the cave wall to prevent water seepage; to ensure that the clay filling is dense, brickwork is set at both ends of the clay filling section, and the brickwork is tightly attached to the cave wall to prevent seepage. The technical solution of the present invention is safe, reliable, efficient, and fast, and complies with relevant national technical specifications, greatly improving the airtightness and firmness of the plugging of mine water gushing, and eliminating the environmental pollution risk of abandoned mine water gushing.

The invention discloses a bipolar plate with a composite carbon coating, a preparation method, an electrode and a battery, the bipolar plate comprises a substrate layer, a transition layer and a composite functional layer, the substrate layer is a metal layer formed by depositing metal Me on the surface of a substrate; the transition layer is formed on the substrate layer and is a metal Me / C layer; the composite functional layer is formed on the transition layer and is far away from the transition layer and comprises a first GLC layer with internal stress relieving and electron conduction functions, a tetrahedral amorphous carbon ta-C layer with a corrosion ion blocking function and a conductive and hydrophobic second GLC layer which are sequentially arranged. The coating provided by the invention has relatively low contact resistance, good ion corrosion resistance and hydrophobic property, and meets the requirement of long-term service of a fuel cell under a durable working condition.

The invention relates to the technical field of sealing rings, in particular to a micro-textured super-wear-resistant sealing ring and a preparation method thereof. The sealing ring is composed of a rubber ring base body, a silicon transition layer and a silicon-doped diamond-like functional layer, a micro-texture area is arranged on the whole or part of the surface of the rubber ring base body, pits are formed in the micro-texture area, the silicon transition layer is attached to the whole or part of the surface of the rubber ring base body, and the silicon-doped diamond-like functional layer is arranged on the silicon-doped diamond-like functional layer. The silicon transition layer covers all or part of the micro-texture area, and the silicon-doped diamond-like functional layer is attached to the silicon transition layer. The sealing ring is small in friction coefficient, high in bonding strength, high in hardness, good in wear resistance and long in service life.

The invention belongs to the technical field of negative electrode materials, and particularly relates to a graphite coating method. By adopting a three-step method of low-temperature softening, aqueous solution washing and high-temperature carbonization, the staged control of the contents of the three components in the working procedures is realized, and the content of each component of the asphalt in each working procedure is always in the optimal ratio. According to the invention, the uniformity in the coating process can be ensured, the coking value can be increased, and the hardening degree of the material can be reduced, and the adopted aqueous solution detergent can also ensure the full reaction of the organic polymer material and the components in the asphalt, and does not remain in the graphite material, so that the negative gain effect is avoided. The method disclosed by the invention is simple in process flow, low in volatile pollutant emission, low in production cost and suitable for large-scale industrialization.

The utility model discloses a kind of multi-material adhesive type's gluing compound machine, including rack, the rack front end is equipped with installation area, processing area, clamping area, collection component, the processing area is located above installation area, the clamping area is located above processing area, the collection component is located installation area, processing area and clamping area right side, to ensure that for a variety of materials are bonded, further ensure that repeated bonding without multiple equipment, in turn reduce the work length, to increase the production efficiency of factory, to reduce use cost, to ensure that material one and material two, material three in the process of adhesion, can adjust position at any time, to ensure that guarantee material does not appear complex deviation.

The present invention discloses a nucleic acid aptamer of uridine diphosphate and a screening method and application thereof, wherein the sequence of the nucleic acid aptamer is shown in SEQ ID NO: 1; the screening method is CIVT-SELEX, i.e., the Capture-SELEX method is first used for primary screening to obtain a single-stranded nucleic acid that can bind to a target ligand, and then the in vitro transcription process is used for screening again, thereby obtaining a nucleic acid aptamer that undergoes a significant conformational change after binding to the target ligand. The present invention successfully obtains a nucleic acid aptamer sequence that can detect uridine diphosphate in an enzymatic reaction solution in a single-stranded linear form, and can respond to different concentrations of uridine diphosphate during in vitro transcription to activate and regulate downstream gene transcription; CIVT-SELEX is expected to be applied to the screening of aptamer sequences of other target ligands, and can be used for detection and as a gene element in a gene circuit for regulation.

This utility model relates to the field of thermal printhead manufacturing technology, specifically a wear-resistant thermal printhead heating substrate with a reasonable structure, simple manufacturing, and effective protection of the silver COM electrode, thereby improving product reliability. A wear-resistant protrusion is provided on the paper output side of the heating resistor. The height of the wear-resistant protrusion is not less than the height of the glass glaze protective layer above the common COM electrode. The wear-resistant protrusion is disposed on the surface of the glass glaze protective layer and located between the heating resistor and the common COM electrode. A ceramic outer protective layer is also provided on the glass glaze protective layer on the surfaces of the heating resistor and the common COM electrode. Compared with the prior art, the beneficial effects are that the wear-resistant protrusion can effectively reduce the contact between the rubber roller and the protective layer on the surface of the silver common electrode on the paper output side, reducing the risk of film peeling off the protective layer on the surface of the silver common electrode; at the same time, the ceramic outer protective layer can further enhance the wear resistance of the glass glaze of the protrusion, significantly improving product reliability.

This invention provides a method for manufacturing a diamond wire saw for cutting silicon carbide single-crystal substrates. First, impurities are removed from the diamond micro-powder abrasive. During the abrasive application process, the abrasive density *a* on the steel wire is monitored in real-time via images and videos, and the feeding rate of the diamond micro-powder abrasive in the feeding container is controlled accordingly, achieving a first-step closed-loop control. In the subsequent nickel plating thickening process, the concentricity of the thickened layer on the steel wire and the continuous stability of its thickness are controlled. Before winding, the wire saw diameter *d* is measured using a laser method. Based on the mapping relationship between the wire diameter *d*, abrasive density *a*, and plating thickness *c*, a second closed-loop control is implemented for the entire wire saw production process. The two closed-loop controls operate nested together, ensuring precise control throughout the entire process. The diamond wire saw obtained by this method exhibits high continuous stability in various performance indicators, ensuring good process stability during the cutting of single-crystal silicon carbide substrates, thereby reducing cutting risks.

The utility model discloses artificial turf bottom back hot melt adhesive roll coating equipment, which relates to the technical field of artificial turf processing and comprises a first support plate, a first conveying roller is rotatably mounted on the inner side of the first support plate, a first guide roller is rotatably mounted on one side of the first support plate, and a limiting mechanism is arranged at one end of the first support plate. A rack is arranged on the right side of the limiting mechanism, a glue rolling mechanism is arranged on the right side of the rack, a fourth supporting plate is arranged on the right side of the glue rolling mechanism, a third guide roller is rotationally installed on the inner side of the fourth supporting plate, a second supporting plate is arranged on the right side of the fourth supporting plate, and a second conveying roller is rotationally installed on the inner side of the second supporting plate. According to the glue adding device, the pressure sensor on the limiting cross rod can be driven to make contact through the upwards-moving connecting rod, so that the pressure sensor can make an external controller give an alarm for reminding, a user can conveniently add glue into the glue coating box in time, and the glue rolling work is prevented from being affected.

The application discloses a kind of coated ternary positive electrode material and its preparation method, battery, which includes ternary positive electrode material core, gradient Al2O3 inner coating layer and LiAlO2 outer modification layer from inside to outside in sequence;Gradient Al2O3 inner coating layer includes inner layer Al2O3 and outer layer Al2O3, the thickness of inner layer Al2O3 is less than the thickness of outer layer Al2O3, and the density of inner layer Al2O3 is greater than the density of outer layer Al2O3.The application solves the problems of large interface impedance of traditional coating material, easy cracking and falling of coating layer in the cycle process, serious structure degradation under high voltage by gradient Al2O3 inner coating layer and outer layer high ionic conductance LiAlO2 outer modification layer, and prepares coated high-nickel ternary positive electrode material with strong interface stability, low impedance and excellent cycle life, effectively improves the electrochemical performance of battery under high-voltage working condition, and is suitable for high-energy-density power battery and energy storage battery field.

This invention relates to the field of coating technology, and discloses a composite CVD coating, its preparation method, and its application. The coating comprises, from the inside out, a base layer, a first spacer layer, a first composite layer, and a second composite layer, arranged sequentially on the surface of a substrate. The first composite layer consists of a transition layer and a second spacer layer; the second composite layer consists of a third spacer layer and a surface layer; both the base layer and the surface layer are TiN; the first, second, and third spacers are MT-TiCN, κ-Al₂O₃, and TiC, respectively; the transition layer includes HT-TiCN and TiCO. The coating provided by this invention has good adhesion, strong resistance to crack propagation, and excellent overall coating quality; simultaneously, the coating particles are fine, and the surface roughness is low, which is more conducive to chip removal during processing.

The invention discloses a preparation method of a ceramic dielectric filter, which comprises the following steps: proportioning and stirring an adhesive and ceramic powder to obtain primary slurry; pre-treating the primary slurry of the first dielectric protection layer to obtain dielectric slurry; pasting a polyester film on the metal bearing plate, and printing a first dielectric protection layer dielectric paste with a preset thickness on the first dielectric protection layer polyester film to obtain a first dielectric protection layer; printing electrode slurry with a preset thickness on the first medium protection layer, and performing drying treatment to obtain an electrode material; printing first dielectric protection layer dielectric paste with a preset thickness on the first dielectric protection layer electrode material to form a second dielectric protection layer and obtain a primary ceramic dielectric filter; and drying and laminating the primary ceramic dielectric filter with the first dielectric protection layer to obtain a finished ceramic dielectric filter product. The conductive performance of the ceramic dielectric filter is improved, and meanwhile the voltage resistance of the ceramic dielectric filter is improved.

The present invention relates to an automatic packaging device for motor rotor core magnetic steel, comprising one or more parallel glue injection main machines, and a rotor core supply device matched one-to-one with each of the glue injection main machines; it also comprises a glue particle supply device, a waste glue material collection unit, a glue particle and waste glue material conveying unit matched with the glue particle supply device and the waste glue material collection unit, and a control unit; the purpose is to provide a packaging device that can realize automatic mass production of high-quality and high-capacity motor rotors by supplying small glue particles.

The utility model relates to the technical field of physical therapy hot compress, and discloses a physical therapy hot compress device which comprises a placing bag, a placing groove is formed in the front face of the placing bag, a heat preservation mechanism is installed in the placing groove, and the front face of the heat preservation mechanism is connected with a heating mechanism through a power line power source. Protection mechanisms are fixedly connected to the peripheries of the upper end and the lower end of the containing bag, a fixing mechanism is fixedly connected to the surface of the containing bag, and an anti-lost mechanism is fixedly connected to one side of the fixing mechanism. According to the physical therapy hot compress device, through the arrangement of the heat preservation mechanism and the heating mechanism, when the device is used, a heating pipe is started, the heating pipe provides needed heat for soybeans, the soybeans absorb and store the heat, a lasting warm effect is conveniently provided for hot compress of a patient, the burden of traditional Chinese medicine is relieved, a bolt is rotated to be separated from a fixing plate threaded sleeve, and the heat preservation effect is good. Soybeans and the heating pipe are convenient to disassemble, assemble and replace, and the usability of the device is improved.

The invention discloses a preparation method of a composite aluminum current collector, which comprises the following steps: S1, selecting a polymer film material as a base film layer of the composite aluminum current collector; s2, aluminum seed layers are formed on the two sides of the base film layer through a magnetron sputtering method; s3, the aluminum seed layer is electroplated and thickened through an ionic liquid electroplating method, and aluminum-containing layers on the two sides of the base film layer are formed; in the step S3, an EMIC-chlorine salt system is selected as an electroplating solution. The composite current collector is prepared by adopting an ion electroplating method, a layer of composite aluminum foil with high tensile strength is deposited on the surface of a polymeric membrane through a magnetron sputtering and ion electroplating technology, and a plating layer with high corrosion resistance and high toughness is obtained by optimizing an electroplating liquid system.

The invention relates to a preparation method of a photovoltaic module and the photovoltaic module, and the method comprises the steps: providing a back contact solar cell, printing insulation paste on the backlight surface of the back contact solar cell, carrying out light curing treatment on the insulation paste, carrying out heat curing treatment on the insulation paste, and enabling the time T1 of the light curing treatment to meet the condition that T1 is more than or equal to 1s and less than or equal to 3s, and enabling the time T2 of the heat curing treatment to meet the condition that T2 is more than or equal to 15s and less than or equal to 35s. The double curing process combining light curing and heat curing is adopted for the insulating glue on the backlight surface of the back contact solar cell, so that the curing time of the insulating glue can be shortened, the curing efficiency of the insulating glue can be improved, the production efficiency of a photovoltaic module can be improved, the bonding performance of the insulating glue can be improved, and the adhesive force between the insulating glue and the back contact solar cell can be enhanced; therefore, the stability and the reliability of the back contact solar cell are improved, the high temperature resistance of the insulation paste is improved, and the possibility of short circuit of the back contact solar cell caused by reduction and even failure of the insulation effect of the insulation paste under the influence of high temperature is reduced.

The invention provides a preparation process of an oleophylic adhesion-resistant film layer of a perfume glass bottle. The preparation process sequentially comprises the steps of ultrasonic cleaning, surface activation, polymer solution spin coating and low-temperature cross-linking curing. The method comprises the following steps: firstly, sequentially adding a water-based decontamination solution, ethanol and deionized water into a glass bottle, and treating in an ultrasonic field of 30-45kHz, so that pollutants on the surface of the inner wall are separated; according to the invention, the low-temperature cross-linked solvent-resistant polymer film layer is formed on the inner wall of the glass, so that the film layer constructs a compact extraction-resistant network structure at 60-90 DEG C, and the permeation rate of ethanol and essential oil to the film layer can be reduced, so that the thickness stability of the film layer is kept for a long time in a closed and high-volatility perfume system; the anti-fingerprint film does not have swelling, softening or demolding phenomena, and is soaked in 85% ethanol and limonene essential oil for 72 hours, the thickness change rate of the film can be controlled below 5%, and the problem that a traditional anti-fingerprint film is easy to lose efficacy in a perfume bottle environment is effectively solved.

The invention discloses an anti-sulfadiazine nano antibody and application thereof, and belongs to the technical field of nano antibodies. The invention aims to provide a nano antibody for detecting sulfadiazine, which has the advantages of small molecular weight, strong penetrating power, good stability and strong antigen binding capacity, and can recognize antigen epitopes which are difficult to recognize by conventional antibodies. The invention provides a nano antibody for detecting sulfadiazine. An amino acid sequence of a CDR1 of a variable region of the nano antibody is shown as SEQ ID NO.6, an amino acid sequence of a CDR2 of the variable region of the nano antibody is shown as SEQ ID NO.7, and an amino acid sequence of a CDR3 of the variable region of the nano antibody is shown as SEQ ID NO.8. The indirect competitive ELISA method established by the invention is a simple, rapid, sensitive and low-cost immunodetection method, and has a great application prospect in detection of sulfadiazine residues in animal-derived food.

A reciprocating compressor according to one embodiment of the present specification is provided with a discharge unit comprising: a first discharge muffler having a first muffler body and a first muffler cover coupled to the first muffler body; a second discharge muffler having a second muffler body and a second muffler cover coupled to the second muffler body; a first discharge hose connecting the first discharge muffler and the second discharge muffler; and a second discharge hose connected to a discharge pipe that couples the second discharge muffler to a sealed container. Furthermore, the first discharge hose connecting the first discharge muffler and the second discharge muffler is made of a flexible material, and the second discharge hose connecting the second discharge muffler and the discharge pipe is made of a metal material. According to the reciprocating compressor with the structure, vibration generated in the compressor main body can be effectively blocked, the combination of the discharge hose and the discharge pipe can be reliably maintained, and noise of a desired frequency can be effectively reduced by adjusting the volume of the first discharge silencer and the volume of the second discharge silencer.

The present application provides an automotive circuit board and a tinning treatment method thereof. The above-mentioned tinning treatment method for automotive circuit boards includes the following steps: photocuring the ink layer on the circuit board to obtain a photocured circuit board; degreasing the photocured circuit board to obtain a degreasing circuit board; microetching the degreasing circuit board to obtain a microetched circuit board; prepregging the microetched circuit board to obtain a prepreg circuit board; sequentially adjusting the temperature and complex concentration of the tinning solution to make the temperature of the tinning solution reach 66°C to 70°C and the complex concentration reach 140g / L to 160g / L; placing the prepreg circuit board into the adjusted tinning solution for chemical tinning. The above-mentioned tinning treatment method for automotive circuit boards has the advantages of being able to reduce the attack of the solution on the solder resist ink and reduce the depth of side etching while ensuring the deposition rate.

The present invention relates to a process for preparing an unfired glaze with antibacterial function, and belongs to the technical field of ceramic processing. The present invention discloses a process for preparing an unfired glaze with antibacterial function, wherein glaze C is prepared by glaze A and glaze B, and glaze C, an antibacterial dopant, melamine formaldehyde resin, etc. are mixed to obtain an unfired glaze with antibacterial function. The comprehensive performance of the glaze is improved by the van der Waals force between polystyrene microspheres and inorganic fillers, the hydrophilicity of polyvinyl pyrrolidone, and the chemical bonds and van der Waals forces in the antibacterial dopant; in addition, by adding a silane coupling agent, a silicate curing agent, a photocuring initiator and melamine formaldehyde resin, a composite cross-linked network structure is formed, the binding force between the antibacterial dopant and the glaze is enhanced, and the antibacterial effect is synergistically improved.

The utility model discloses a multifunctional gasket assembly for a power interface of a computer mainboard, which comprises a gasket main body piece, the gasket main body piece comprises a bottom film and a conductive foam assembly, the bottom film is provided with an adhesive surface, the conductive foam assembly comprises a conductive foam block and a conductive fabric arranged on one side of the conductive foam block, and the conductive fabric is arranged on the other side of the conductive foam block. The conductive cloth is arranged on the rubber surface of the bottom film, and the side, deviating from the conductive cloth, of the conductive foam block is a rubber surface and is used for being matched with a power interface; a release film is further arranged on the base film at the position of the conductive foam assembly, a part of the conductive cloth is in contact with the release film, and the release surface of the release film is in contact with the conductive cloth. The multifunctional gasket assembly can provide better buffering and damping functions, conductive functions and electromagnetic shielding functions, and can well meet the requirements of a computer mainboard power interface for the stability of electrical connection and the reliability of a mechanical structure.

The invention relates to a vehicle hydrogen storage bottle opening sealing structure which comprises a plastic inner container, a bottle valve seat, a connector and a locking nut, the bottle valve seat is located at a bottle opening of the plastic inner container, the connector is tightly connected into the bottle opening of the plastic inner container through a sealing structure, and the sealing structure and the plastic inner container are sealed by pressing the connector downwards through the locking nut and extruding the sealing structure. The metal connector, the sealing ring and the bottle opening of the plastic inner container are extruded to achieve sealing, the plastic inner container adopts the injection molding technology, the cylinder valve seat serves as an embedded part, the shoulder of the cylinder valve seat is wrapped in the plastic inner container, the binding force of the cylinder valve seat and the plastic inner container in the long-term working process of the gas cylinder is guaranteed, separation is avoided, and the service life of the gas cylinder is prolonged. The cylinder valve seat, the connector and the locking nut are simple in structure and easy to machine, the cylinder valve seat is fixed through the fixing tool, sealing can be achieved by screwing the locking nut through a tool wrench, and installation is convenient.

This invention relates to a method for enhancing the stirring intensity during vanadium extraction, belonging to the field of steel pretreatment. The method includes the following three steps: first, vanadium-containing molten iron is added to a converter; then, a top-and-bottom blowing process is used for smelting; coolant is added according to the composition and temperature at the smelting endpoint; finally, semi-steel is removed from the lance at the smelting endpoint. The top-blown gas is an oxygen-nitrogen mixture, and the total flow rate of the oxygen-nitrogen mixture is 31,000~35,000 Nm³. 3 / h; the oxygen consumption per ton of iron, the top blowing lance position, and the nitrogen consumption per ton of iron are controlled in segments according to the blowing period; the bottom blowing gas is nitrogen, and the nitrogen supply intensity is controlled in segments according to the blowing period. This invention significantly enhances the stirring intensity of the molten pool without significantly increasing the temperature rise rate through the synergistic effect of the high-flow-rate oxygen-nitrogen mixed gas from the top and the variable-flow-rate nitrogen from the bottom, thereby shortening the mixing time and enhancing the slag-metal reaction, further increasing the vanadium oxidation amount and further reducing the TFe content in the vanadium slag.

The invention discloses a high-performance aluminum alloy composite board for a liquid cooling runner plate of a power battery and a preparation method of the high-performance aluminum alloy composite board, the high-performance aluminum alloy composite board is formed by rolling and compounding a brazing layer, a core material layer and a corrosion-resistant layer, and the core material layer is prepared from the following raw materials in percentage by mass: 0.4-1.0% of Si, 0.2-0.7% of Fe, 0.2-1.1% of Cu, 1.2-1.8% of Mn, less than or equal to 0.05% of Zn, 0.05-0.3% of Ti, less than or equal to 0.05% of single content of other elements, less than or equal to 0.15% in total and the balance of Al. The preparation method of the high-performance aluminum alloy composite board comprises the steps of casting, homogenizing annealing, surface treatment, skin material hot rolling cogging, mechanical welding, heating before rolling, hot rolling compounding, cold rolling, finished product annealing, finishing and shearing. The high-performance aluminum alloy composite board provided by the invention is high in strength, high in ductility, excellent in forming performance and excellent in corrosion resistance after brazing.

The utility model discloses an unwinding and preheating device for a reinforcing line of an EPDM (Ethylene-Propylene-Diene Monomer) rubber sealing strip and belongs to the technical field of sealing rubber strip production equipment. Comprising two unwinding structures, a preheating structure, a side-by-side traction structure and a rack, each unwinding structure comprises a wire coil, a front traction mechanism and a conveying mechanism, the two unwinding structures are arranged on the rack and work simultaneously or only one of the two unwinding structures works, and the two conveying mechanisms are arranged side by side up and down; the two wire coils are arranged front and back side by side; the two front traction mechanisms are located over the two wire coils respectively, are arranged side by side in a front-back mode and can be adjusted on the machine frame in a front-back mode. Reinforcing wires output by the front wire coils pass through the corresponding front traction mechanisms to the upper conveying mechanism, and reinforcing wires output by the rear wire coils pass through the corresponding front traction mechanisms to the lower conveying mechanism. The side-by-side traction structure is arranged between the unwinding structure and the preheating structure, located right behind the position between the two conveying mechanisms and used for pulling the two reinforcing wires backwards side by side in the left-right direction.

The present invention provides a pad, a cover plate and a lubricating heat-dissipating adhesive, wherein the pad comprises a wood fiber board and facial paper attached to the upper and lower surfaces of the wood fiber board, an adhesive layer is arranged between the wood fiber board and the facial paper, the adhesive layer is an adhesive layer formed after the lubricating heat-dissipating adhesive is heated and cured, and the lubricating heat-dissipating adhesive comprises polyethylene oxide, polyethylene glycol, an aqueous amino coupling agent, a polyether surfactant and a hydrophilic solvent. In the present invention, the lubricating heat-dissipating adhesive can not only ensure the bonding force between the facial paper and the wood fiber board, but also give full play to the overall heat dissipation and lubrication effect of the functional materials polyethylene oxide and polyethylene glycol. Therefore, when the pad prepared based on the lubricating heat-dissipating adhesive of the present invention is used for PCB drilling, the pad can effectively reduce the temperature of the drill needle, thereby reducing the wear of the drill bit and reducing the adhesion of drill cuttings to the drill needle, and the quality of the hole wall is significantly improved.