186 results about "Prawn" patented technology

The invention discloses a shrimp health state early warning method and system based on water quality monitoring, and aims to improve the disease prevention and control efficiency in a shrimp culture process. The method comprises the following steps: collecting historical breeding disease data and water quality change data of a target shrimp breeding water area, and constructing a water quality pathopoiesis knowledge graph; then water quality change data in a preset monitoring time period is obtained, space-time tracing is carried out by using the water quality change prediction model, and a water quality anomaly propagation path diagram is generated; formulating a water quality monitoring strategy based on the propagation path diagram, and optimizing the layout and frequency of monitoring points; and finally, monitoring the water quality in real time according to the established monitoring strategy, and realizing dynamic early warning of the health state of the prawns by combining real-time monitoring data and a water quality pathopoiesis knowledge graph. Water quality related diseases can be effectively prevented and controlled, and the stability and yield of shrimp culture are improved.

The invention relates to the technical field of prawn culture, in particular to a high-density culture optimization method for penaeus monodon based on multi-source culture environment analysis. A scale evaluation system of different preset cultivation environment condition combinations is built based on high-density penaeus monodon cultivation to evaluate the trend radiation diagram, whether the current cultivation density scale of the penaeus monodon is reasonable or not is analyzed through thermal polymerization after evaluation, and a multi-source cultivation environment analysis result is obtained; if one or more high-density abnormal breeding areas exist in a multi-source breeding environment analysis result, a simplex table model is constructed with the maximum bearing force as a constraint and the expected breeding density coefficient as a target function, and the optimal solution of the simplex table model is solved to determine the optimal breeding density scale of the high-density abnormal breeding areas. According to the method, the multi-source culture environment data can be fused to reasonably and scientifically analyze the high-density culture of the penaeus monodon and make an accurate and optimized culture strategy, so that the yield of the penaeus monodon per unit area is increased, and the low survival rate of the high-density culture is improved.

The present application belongs to the field of aquaculture technology, and mainly relates to a traditional Chinese medicine composition for preventing and treating acute hepatopancreas necrosis disease of prawn, a preparation method and application. The traditional Chinese medicine composition comprises the following raw materials in parts by weight: 28-32 parts of Radix Sanguisorbae, 28-32 parts of Radix Scutellariae, 18-22 parts of Phellodendri Cortex and 8-12 parts of Lonicerae Japonicae Flos. The traditional Chinese medicine composition can significantly inhibit the activity of the main pathogen of the disease, i.e. Vibrio parahaemolyticus, improve the immune function and disease resistance of prawn, and further repair the hepatopancreas and intestinal tissues of the diseased prawn, thereby achieving the effect of effectively preventing and treating the acute hepatopancreas necrosis disease of prawn.

The invention relates to the technical field of aquatic product freezing processing, and discloses a prawn freezing process dynamic regulation and control method and system, and the method comprises the steps: extracting a damage feature vector through a lightweight instance segmentation network; generating a lightweight knowledge graph based on knowledge distillation; the damage features are converted into symbolic representation, and neural symbolic reasoning is carried out; calculating a quality degradation risk index and generating a differential control parameter; and collecting feedback data and updating the weight of the knowledge graph. According to the method, the technical problems of low response speed and poor interpretability in the freezing process of the damaged prawns are solved, and millisecond-level real-time decision and accurate control are realized.

The invention discloses a multiplex fluorescent quantitative PCR (polymerase chain reaction) detection kit for prawn culture pathogenic bacteria, which is characterized in that the kit contains primers and probes for detecting the prawn culture pathogenic bacteria, wherein the primers and the probes are respectively used for detecting TDH-related hemolsin genes of vibrio parahaemolyticus, ORF107 genes of white spot syndrome viruses, small subunit ribosomal genes of shrimp enterocytozoon hepatopenaei, 37 kDa coat protein genes of infectious subcutaneous and hematopoietic necrosis viruses, DNA (deoxyribonucleic acid) primer genes of full-eye iridovirus 1 and PirA [pi] genes of pathogens of bacterial prawns acute hepatopancreas necrosis; the method has the advantage that the detection of eight prawn culture pathogens can be realized at the same time. The method comprises the following steps of: obtaining a tcdB gene of a high-pathogenicity vibrio and a hemolsin gene of a vibrio harveyi;

The invention provides acinetobacter for culturing prawns in saline-alkali water and application of the acinetobacter. The preservation number of the provided acinetobacter is CGMCC (China General Microbiological Culture Collection Center) No.36066. The acinetobacter soilis strain provided by the invention has remarkable comprehensive application advantages, can still keep higher growth activity and metabolic capability in a low-temperature environment, and continuously plays a water body purification function. Ammonia nitrogen and nitrite nitrogen in a water body can be efficiently degraded, the environment of the aquatic water body is remarkably improved by promoting the nitrogen circulation process, and harm caused by nitrogen pollution is reduced. In addition, the strain can effectively inhibit and prevent reproduction of pathogenic vibrios and reduce the occurrence risk of bacterial diseases of aquatic animals. The strain is high in safety, does not cause poison or stress reaction to bred animals even under the condition of high-concentration use, and has good ecological safety and environmental friendliness.

The invention belongs to the technical field of pathogenic microorganism screening, and particularly relates to vibrio parahaemolyticus capable of causing prawn vibrio vitreovibriosis and application of the vibrio parahaemolyticus, and the pathogenic bacteria can be used for preparing inactivated vaccines or used as the pathogenic bacteria to screen medicine components with the effect of preventing and treating the prawn vibrio vitreovibriosis or a culture method. The preservation number of the vibrio parahaemolyticus provided by the invention is CGMCC (China General Microbiological Culture Collection Center) The pathogenicity of the vibrio parahaemolyticus with high pathogenicity and strong lethality is about 1000 times stronger than that of the vibrio parahaemolyticus which is collected by the world animal hygiene organization and causes acute hepatopancreatic necrosis, and the strain is popular in main prawn culture areas and causes serious harm to the prawn fry culture industry in China. The vibrio parahaemolyticus provided by the invention can be used as a positive control for preparing a diagnosis product for the prawn vibrio vitreovirus disease; or preparing an immune vaccine after inactivation.

The invention relates to a penaeus vannamei greenhouse circulating water mode pond opening which comprises a greenhouse building, a circulating water treatment system, an intelligent oxygenation system, a precise feeding system and an intelligent management and control platform. The circulating water treatment system purifies tail water through a microfilter and a biochemical pool and recycles the tail water; the intelligent oxygenation system adopts a nano aeration disc which is controlled in a subarea manner, and has a daily mode and a feeding mode; the precise feeding system realizes on-demand feeding based on machine vision and an AI algorithm; the intelligent management and control platform integrates all subsystems, and automatic closed-loop management under data driving is achieved. According to the invention, high-density, full-year, intelligent and unmanned prawn culture is realized, the yield and the survival rate are effectively improved, and the feed consumption, the labor cost and the influence on the environment are reduced.

1. The name of the design product: fishing net. 2. The use of the design product: for fishing fish and prawn. 3. The design points of the design product: the combination of shape and pattern. 4. The picture or photo that best shows the design points: perspective view.

The application provides a breeding method for improving high-temperature tolerance of prawns, which comprises feeding a physical strength enhancer before high-temperature stress, wherein the physical strength enhancer comprises the following components: sea moss extract, tannic acid and astragaloside IV; the temperature is raised at a temperature raising rate of 0.5-2 DEG C per 10-14 hours, and one high-temperature stress is performed by continuously raising the temperature for 2-4 days; and the high-temperature stress is performed for 5-10 times in total during the breeding. The sea moss extract, tannic acid and astragaloside IV are used to prepare the physical strength enhancer before high-temperature stress, and the breeding method combining the high-temperature stress with a specific temperature raising rate is helpful to improve the resistance and tolerance of prawns to high-temperature environmental changes, and to improve the survival rate of prawns, and the average survival rate of prawns is more than 90%.

This invention relates to the application of a fermented shrimp shell feed compound in sandworm farming, belonging to the field of feed. This invention utilizes the abundant shrimp resources in Zhanjiang to process shrimp shells, and through quality improvement and fermentation technology, develops a feed-saving animal protein source—shrimp shell protein; then, it combines this with algae and other ingredients to create a special feed for sandworm farming. This establishes a specialized, serialized, efficient, and precise fermented feed product system for aquaculture animals. It achieves the recycling of agricultural waste within the same region and enables high-density indoor farming of Zhanjiang sandworms.

The utility model discloses a kind of for shrimp culture's ration feeding device, the utility model relates to aquaculture technical field;Including: base, the top of the base is fixedly connected with support structure, the outer wall of the support structure is fixedly connected with storage hopper and discharge structure;The discharge structure includes drive motor, the output shaft of the drive motor is fixedly connected with connecting rod, the bottom of the connecting rod is fixedly connected with discharge block, the top of the discharge block is evenly provided with a plurality of discharge holes, the bottom of the discharge block is fixedly connected with feeding structure, the top of discharge block evenly provided with a plurality of discharge holes, with the connecting rod rotation of drive motor drive, can the feed in storage hopper ration delivery to feeding structure, compared with the mode that traditional artificial is estimated feeding amount by experience, effectively avoid the feed waste and water pollution caused by feeding too much, and the problem that feeding deficiency affects the growth of prawn.

The utility model provides a kind of clamping device, shelling equipment and shrimp production line, it is related to shrimp production technical field.First clamping piece is fixed in mounting seat, the first end of second clamping piece in first direction is connected with mounting seat, the second end of second clamping piece in first direction is free end, second clamping piece can be deformed, first clamping piece and second clamping piece are spaced apart, and first clamping piece and second clamping piece are enclosed to set up clamping space;Mounting seat is connected with driving mechanism, to make mounting seat be driven rotation by driving mechanism.In the use of clamping device, shelled shrimp is arranged in clamping space, under the action of inertia, second clamping piece deforms, and first clamping piece and second clamping piece are all attached with shelled shrimp, to clamp shelled shrimp in clamping space.Such, since second clamping piece can be deformed, this makes second clamping piece closely adhere to the curve of shelled shrimp by deformation, and the stability of shelled shrimp clamping is guaranteed.

The prawn posture self-adaption clamp comprises a downward pressing mechanism, the downward pressing mechanism is connected with a control mechanism, the bottom of the control mechanism is connected with a clamping mechanism through a rotating mechanism with a rotating shaft in the vertical direction, the clamping mechanism comprises a plane clamping piece and an arc-surface clamping piece, and the bottom end of the arc-surface clamping piece is provided with a chamfering structure bent towards the plane clamping piece. A chamfering inner side structure is arranged on the surface of one side, facing the prawn clamping position, of the chamfering structure; two sides of the control mechanism are respectively connected with a visual identification unit and a pressing mechanism; the device integrates a visual identification unit, an asymmetric clamping mechanism composed of a cambered surface clamping piece and a plane clamping piece, a rotating mechanism and a pressing mechanism, so that full-process automatic operation of prawn identification, orientation, posture adjustment and tail embedding is realized.

The application discloses a water surface weeding device for South American prawn culture, which comprises a water weed synchronous collection and removal mechanism and a water weed removal boat, wherein the water weed synchronous collection and removal mechanism is arranged on the water weed removal boat, and the water weed synchronous collection and removal mechanism comprises a fixed shaft, a conical winding roller, a cutter and a water removal assembly; the water weed removal boat is provided with a protective baffle; the fixed shaft is arranged on the protective baffle; the conical winding roller is rotatably sleeved on the fixed shaft; the conical winding roller is provided with a rotating shaft; the rotating shaft is rotatably arranged on the protective baffle; the cutter is arranged on a smaller-diameter end of the conical winding roller; and the water removal assembly is arranged on the conical winding roller. The application relates to the technical field of water surface weeding devices, and particularly provides a water surface weeding device for South American prawn culture.

The application discloses an automatic oxygenation device for South American prawn culture ponds, which comprises a floating mechanism, wherein the floating mechanism comprises a floating plate and a float, the float is arranged on the floating plate, and a surge oxygenation mechanism and a non-powered self-translation mechanism are arranged on the floating mechanism. The application relates to the technical field of oxygenation devices, and particularly provides the automatic oxygenation device for South American prawn culture ponds, which can generate more bubbles, has a better oxygenation effect, can generate a surge effect in the oxygenation process, can diffuse the bubbles to a larger range, has a larger oxygenation range, can move in the culture pond in the oxygenation process without any independent drive, has a wider action range, and can actively control the moving speed.

The utility model discloses a shell collecting device for industrial culture round ground shrimps, which belongs to the field of aquaculture, solves the problem that omission still exists when the existing shrimp shell collecting device is used for filtering shrimp shells, and comprises a collecting mechanism arranged in a culture pond, the top end of the collecting mechanism is communicated with a conveying pipe, and a collecting mechanism is arranged at the end part of the conveying pipe. The collecting mechanism comprises a collecting robot, a control panel and a shifting frame, the air pressure mechanism, the collecting mechanism and the collecting mechanism are arranged, a water source is pushed through high-pressure air, shrimp shells in the water source move towards the side close to the collecting robot, and when the shrimp shells move to the lower end of the collecting robot, the shrimp shells are collected through the shifting frame. Through operation of a detection camera in the collection robot, the collection accuracy is guaranteed according to comparison of photos, then prawn shells are independently stored through a conveying pipe and a collection bin, the working quality during equipment operation is guaranteed, and the working efficiency of the equipment is improved.

The application discloses a kind of salt and alkali land breeding with white shrimp of South America compound feed raw material crushing equipment, it is related to white shrimp of South America compound feed raw material crushing technical field, the side surface of the crushing tank is fixedly connected with control panel, the bottom of the crushing tank is fixedly connected with driving part, the side of the crushing tank away from control panel is fixedly connected with discharge part, the present application is provided with contact mechanism, the output end of driving part drives crushing rod to rotate continuously, so that when the material in the crushing tank is slowly discharged, the extrusion force of the material in the tank to sliding plate is less than the centrifugal force when crushing rod rotates, sliding plate and sliding rod are moved to the inside of the crushing tank by the action of centrifugal force, so that sliding plate drives rubber block to move to the inside of the crushing tank, while colliding with the inside of the crushing tank by rubber block, while the impact force generated by vibration, part of the impurities attached in the inside of the tank is shaken off.

The invention discloses a penaeus vannamei body size estimation method and device and a storage medium, and relates to the technical field of breeding industry image processing, and the method comprises the steps: collecting a penaeus vannamei data set image, and carrying out the marking of the penaeus vannamei data set image; constructing a penaeus vannamei body detection model, improving the penaeus vannamei body detection model, and training the improved penaeus vannamei body detection model based on the marked penaeus vannamei body data set image; and based on the trained penaeus vannamei body detection model, measuring the body size of the penaeus vannamei and estimating the length of the penaeus vannamei body. According to the method, the expression and fusion capabilities of the multi-scale features are enhanced, the positioning precision of the feature points of the prawns is improved, and a set of non-contact estimation system for the body sizes of the prawns is developed. The coordinates of the feature points of the shrimp bodies are accurately obtained, the body size indexes are calculated, and accurate estimation of the shrimps with different completeness degrees is achieved. Rapid and accurate non-contact prawn body size measurement is realized, and powerful technical support is provided for intelligent and accurate cultivation of the penaeus vannamei.

The present application belongs to the field of live transportation of aquatic products, and relates to a method for live transportation of prawns without water. The core of the method is to use a staged treatment strategy and the synergistic effect of dormancy induction liquid and moisture supply liquid. First, the prawns are adapted to the environment by fasting and gradient cooling, then they are soaked in pre-cooled dormancy induction liquid to enter a pseudo-death dormancy state and reduce metabolism. Then, the moisture supply liquid soaked sponge is used as a transportation medium, which can form a protective film on the surface of the prawn body to effectively prevent water loss and provide energy. During transportation, the prawns treated with the moisture supply liquid are placed in a sealed box filled with pure oxygen together with the moist sponge, and the prawns are transported without water at low temperature. After the transportation is completed, the prawns are placed in warm water to quickly recover. The prawn live transportation method without water prolongs the survival time of prawns in a water-free environment, improves the transportation efficiency, is simple to operate, and is suitable for large-scale long-distance transportation of prawns.

The utility model discloses an acete chinensis length measuring tool, which relates to the technical field of acete chinensis research and comprises a measuring disc, a plurality of measuring grooves are arranged on the measuring disc, each measuring groove can accommodate a single-tail acete chinensis sample, and a length scale layer is arranged in each measuring groove along the length direction so as to measure the length of the corresponding acete chinensis sample. According to the utility model, the lengths of acete chinensis samples can be measured in batches, and the measurement efficiency and the measurement accuracy are improved.

The invention belongs to the technical field of genetic engineering, and particularly relates to a double-stranded RNA preparation for regulating and controlling shrimp molting as well as a synthesis method and application of the double-stranded RNA preparation. The prawn shelling is regulated and controlled by synthesizing specific double-stranded RNA, and the preparation method of the preparation comprises the following steps: firstly, cloning a target gene cDNA sequence related to the key physiological process of prawn shelling; secondly, constructing the sequence into an in-vitro transcription vector, and extracting and purifying recombinant plasmids; and finally, synthesizing the high-purity and high-stability double-stranded RNA preparation aiming at the target gene by taking the plasmid as a template and utilizing an in-vitro transcription system. In-vivo injection experiments prove that when the dsRNA preparation is injected into the litopenaeus vannamei body, the molting process of the litopenaeus vannamei can be obviously delayed.

The invention provides a multiplex RPA (recombinase polymerase amplification) detection primer probe group, a test strip, a kit and a detection method for three prawn RNA (ribonucleic acid) viruses, and belongs to the technical field of biological detection. The invention provides a multiple RPA (recombinase polymerase amplification) detection primer probe group for three prawn RNA (ribonucleic acid) viruses. The multiple RPA detection primer probe group is designed by taking an IMNV MCP gene, a CMNV RdRp gene and a PvPV RdRp gene as target genes. The primer probe set designed by the invention meets the requirements of multiple RPA detection, and can specifically amplify corresponding viral nucleic acid. The invention also provides multiple RPA (recombinase polymerase amplification) detection capable of completing the three RNA viruses of prawns. When the triple RPA detection method constructed by the invention is used for detecting IMNV and CMNV in a sample, the result is completely consistent with the result of an RT-qPCR detection method. The triple RPA detection method established by the invention can be used for simultaneously detecting three viruses in a shorter time, and has a remarkable on-site detection advantage.

The utility model discloses a kind of separating screening devices for snail and fish and shrimp, relate to aquaculture equipment field.A kind of separating screening devices for snail and fish and shrimp, comprising: bottom plate, the periphery of the upper end of the bottom plate is fixedly connected with support beam, the upper end of the support beam is fixedly connected with fixed column, the upper end of the fixed column is fixedly connected with spring, the upper end of the spring is fixedly connected with first screen frame, the lower end of the inside of the first screen frame is provided with first screen hole, the lower of the first screen frame is provided with second screen frame.Solve the technical problems that the current snail and fish and shrimp sorting process, often rely on manual sorting, time-consuming and labor-consuming, especially in large-scale processing difficult to meet production demand, rely on manual sorting, time-consuming and labor-consuming, especially in large-scale processing difficult to meet production demand, and traditional screen mesh screening is only separated by single aperture, snail hard shell is easy to be stuck in screen hole, fish and shrimp are soft and easy to be squeezed and injured.

The utility model belongs to the technical field of genetic material extraction appliance, concretely relates to special centrifugal tube suit of south American white prawn nucleic acid extraction, including the pipe body, the top threaded connection of pipe body has the pipe cap, the position department of pipe body outer wall is close to the fixed setting of mounting ring of top, the outer wall of pipe cap is below the sliding ring of mounting ring and is connected with the damping sliding, the position department of mounting ring bottom close to the outside edge is hinged with four upper articulated rods at equal intervals, the top of sliding ring is hinged with the lower articulated rod of corresponding position of upper articulated rod, and the corresponding upper articulated rod is hinged with the lower articulated rod between setting articulated assembly. The utility model places the pipe body on the test tube rack through the amplitude of the lower articulated rod and the upper articulated rod protruding from the outside of the pipe body to support the pipe body, so that the pipe body can be adapted to different diameter types of test tube racks, increase the types of centrifugal tubes that can be adapted to test tube racks, facilitate the use of centrifugal tubes, and at the same time, reduce the types of test tube racks that need to be purchased, and reduce the cost of purchasing test tube racks.

The invention discloses a crayfish pizza processing method based on green water retention of shrimp meat and a product of the crayfish pizza processing method, and belongs to the technical field of food processing. According to the invention, alginate oligosaccharide and xanthan gum are mixed to form a composite water-retaining agent to carry out dipping treatment on the small lobster meat, and ultrasonic waves are utilized to generate cavitation and oscillation effects, so that the myofibril structure of the lobster meat is loose, and the composite water-retaining agent is promoted to rapidly permeate into gaps of the myofibril of the small lobster meat, thereby improving the water retention capacity of the lobster meat; the crayfish pizza is prepared by using the crayfish pizza The green water retention method is applied to small lobster meat required by preparation of pizza, and the analysis of the change conditions of indexes such as water-holding capacity, color and texture of the lobster meat in the cold fresh storage process proves that the green water retention method can effectively maintain the water-holding capacity of the lobster meat in the cold fresh storage process and delay the deterioration of the color and texture of the lobster meat.

The utility model discloses a water purification device for prawn culture, which comprises a sediment filter tank, a biological purification tank, an adsorption tank and a disinfection tank, the top of the left end of the sediment filter tank is communicated with the bottom of a water inlet pipeline, a first control valve is arranged at the joint of the water inlet pipeline and the sediment filter tank, and the water inlet end of the water inlet pipeline is connected with a culture pond water outlet pipe; a first filter screen and a second filter screen are arranged in the sediment filter box, the first filter screen is located on the left side of the second filter screen, the right end of the sediment filter box is communicated with the left end of the biological purification box through a communication pipeline, a valve is installed on the communication pipeline, and a cleaning water inlet pipe used during cleaning is arranged at the right end of the sediment filter box. The device realizes graded filtration of solid impurities with different particle sizes in the aquaculture water, can efficiently intercept various solid pollutants such as residual feeds and shrimp shells, effectively reduces the content of suspended solids in the water, and reduces the burden for the subsequent purification link.

The application discloses application of functional bio-floc in prawn culture. Bacillus subtilis XYB4 and neutral protease are added into traditional bio-floc to prepare the functional bio-floc. The functional bio-floc is applied to prawn culture, which not only purifies the culture water quality and effectively reduces the content of ammonia nitrogen and nitrite nitrogen in the culture water, thereby reducing the toxicity of ammonia nitrogen and nitrite nitrogen to prawns, but also improves the growth performance and antioxidant enzyme activity of prawns, so that the green, environmentally-friendly, safe and efficient ecological prawn culture is realized.

The utility model relates to the technical field of aquaculture, and provides a penaeus vannamei boone culture intelligent feeding and water quality purification all-in-one machine which comprises a feeding tank, a buoyancy ring arranged at the lower end of the feeding tank, a distinguishing feeding assembly arranged in the feeding tank, a separation cover of a conical structure, and an extension pipe arranged at the upper end of the separation cover. A feeding port is formed in the upper end of the extension pipe, an extension cavity is formed in the side wall of the separation cover, a feeding tank is inserted into the feeding port, a material guide port is formed in the side wall of the feeding tank, a material stacking port is formed in the side wall of the extension pipe, and the material stacking port corresponds to the material guide port in position. By means of the technical scheme, the problems that in the related technology / prior art, traditional feeding mostly depends on manpower, a large amount of manpower is consumed, the labor intensity is large, the feeding amount and the feeding position are difficult to accurately control, the feeding amount is too large, feed is left in water, waste is caused, and water quality is polluted are solved; the growth and development of the prawns can be influenced when the feeding amount is too small.

The utility model relates to the technical field of shrimp catching facilities, and discloses a shrimp catching ground cage convenient to collect, which comprises a ground cage body used for catching shrimps, a lateral shrimp taking port arranged on the body and a cover plate connected with the body, and the body is provided with a first shrimp inlet, a second shrimp inlet and a third shrimp inlet. A first shrimp blocking net, a second shrimp blocking net and a third shrimp blocking net are sequentially arranged on the inner side of the first shrimp inlet, the inner side of the second shrimp inlet and the inner side of the third shrimp inlet, a top shrimp taking opening is formed in the cover plate, and a protection plate is arranged at the top shrimp taking opening and detachably connected with the cover plate. The ground cage is provided with the top shrimp taking opening and the side shrimp taking opening, when the number of prawns in the cage is large, the elastic plate is pinched and pressed to enable the clamping block to be taken down from the cover plate, then the top shrimp taking opening is opened, the prawns are poured out rapidly, and the reliability of shrimp taking is improved; when the number of the prawns in the cage is small, the sliding plate is pulled, the prawn taking opening in the side is opened, the prawns are taken out from the outlet, and the prawns are taken out from multiple outlets.