26results about How to "Extended dwell time" patented technology

The invention provides a system and a method for treating coexisting new pollutants in drinking water, and the system and the method are characterized in that firstly, ozone microbubble water with small volume and large specific surface area and magnetized superfine activated carbon are used for carrying out oxidation treatment on the coexisting new pollutants and adsorbing pollutants with small molecular weight and relatively high activity; the purpose of removing part of new pollutants is achieved; then, under the irradiation of an ultraviolet lamp tube, the reducing agent catalyzes sulfite to generate reducing free radicals such as hydration electrons [eaq-],. H and SO3., and under the substitution action of iodide ions, reductive dehalogenation and iodine substitution reaction of the halogenated organic matter difficult to degrade are achieved, and reduction removal of new pollutants difficult to degrade is achieved. The system is simple and compact in structure, is a treatment device integrating filtration, oxidation, adsorption and reduction, reduces the occupied area, can realize effective removal of coexisting new pollutants with different molecular characteristics and different reaction activities through multiple actions of physical interception, oxidation, adsorption, reduction and the like, and has a wide application prospect.

The utility model discloses an external circulation self-suction type residual gas recycling reaction device which comprises a reaction kettle body, a stirring paddle is arranged in the reaction kettle body, and the stirring paddle consists of a titanium porous stirring paddle and a stirring rod; the stirring paddle provides stirring power through a variable frequency motor arranged at the top of the reaction kettle; a liquid outlet, a gas outlet, a liquid inlet and a residual gas inlet are formed in the reaction kettle body, the liquid outlet is formed in the upper part of the kettle body, the liquid outlet and the residual gas inlet are formed in the bottom of the kettle body, the liquid outlet is connected with a liquid inlet pipe, the residual gas inlet is connected with a gas inlet pipe, the gas inlet pipe is nested in the liquid inlet pipe, and a three-way pipe is mounted on the liquid inlet pipe. According to the utility model, the design of a self-suction hollow stirring paddle is replaced by the design of external circulation and a large-page porous stirring paddle, so that the corrosion of corrosive gas to the stirring paddle is reduced, the mechanical strength of the stirring paddle is improved, and the service life of reaction equipment is prolonged.

The invention discloses a production device and method for preparing biological aviation kerosene through a hydrodeoxygenation method, the production device for preparing the biological aviation kerosene through the hydrodeoxygenation method comprises a reaction kettle, a stirring assembly is arranged in the reaction kettle, and the stirring assembly is used for stirring a reaction mixture; the stirring assembly comprises a hollow square shaft, a plurality of hollow stirring blades and a driving assembly, and the hollow square shaft is rotationally arranged at the bottom in the reaction kettle; the invention further discloses a production method for preparing the biological aviation kerosene through the hydrodeoxygenation method. The production method comprises the steps of S1, raw material pretreatment; s2, hydrodeoxygenation reaction; s3, separating a product; and S4, rectification. According to the device, hydrogen exhausted from the exhaust holes is sprayed out in all directions, so that the contact area between the hydrogen and raw materials can be increased, the hydrogen reaction is more sufficient and complete, waste is reduced, and meanwhile, the preparation efficiency of the biological aviation kerosene is also improved.

The utility model discloses cat food screening machine equipment, and relates to the field of cat food screening, the cat food screening machine equipment comprises a treatment box body, the bottom surface of the treatment box body is uniformly butted with bottom cushion blocks, one side edge of the treatment box body is horizontally inserted with a collection drawer, one side edge of the treatment box body is obliquely and fixedly provided with a discharge pipeline, and the discharge pipeline is fixedly connected with the bottom cushion blocks. A control panel is fixedly arranged on one side edge of the treatment box body, a side fixing box is fixedly arranged on the side edge, away from a discharging pipeline, of the treatment box body, a top feeding hopper is fixedly arranged on the top face of the treatment box body, bottom screw holes are evenly formed in the bottom face of the treatment box body, and a connecting screw rod is fixedly connected to the top face of a bottom cushion block in an inserted mode. A side through groove is horizontally formed in the side edge, away from the side fixing box, of the treatment box body, a supporting frame body is obliquely and fixedly arranged on the inner side edge of the treatment box body, an integrated sealed structure is adopted, so that the device is cleaner and more efficient during use, and meanwhile, screening is more efficient and comprehensive under the combination of high-amplitude vibration and a stirring structure.

The invention discloses a data caching method, system and device based on a multi-level caching architecture and a medium, and relates to the technical field of data caching, the method comprises the following steps: respectively determining a plurality of logic addresses corresponding to the same data block as associated addresses, and obtaining the address number of the logic addresses of each data block; for each data block, obtaining the access frequency of each associated address in the current cache cycle, calculating to obtain the association strength of each associated address according to the number of logical addresses corresponding to the data block, and deleting the associated address with the lowest association strength until the logical address of the data block is unique when a new logical address needs to be inserted; determining a logic address uniquely corresponding to the same data block as a non-associated address, and when a new data block needs to be inserted, deleting the data block with the lowest access frequency for the insertion of the new data block; and error discrimination of the cache data popularity is reduced and eliminated, and the utilization rate of the cache space is effectively improved.

The submerged staged combustion injector for the small molecule gel oxidizing agent comprises a cylindrical inlet, a conical section, a streaming section, a straight section, an axial connecting section and a radial connecting section which are connected in sequence, the conical section, the streaming section and the straight section are each of a double-layer structure. The outer walls of the conical section, the streaming section and the straight section are sequentially connected to form an outer wall, and the two ends of the outer wall are connected with the cylindrical inlet and the axial connecting section respectively; the inner walls of the conical section, the streaming section and the straight section are sequentially connected to form an inner wall, one end of the inner wall is closed, and the other end is connected with the outer wall; an oxidant chamber is formed by a cavity between the outer wall and the inner wall and the cylindrical inlet; a cavity enveloped by the inner wall forms a secondary fuel combustion chamber; a fuel gas channel is arranged in the conical section and is communicated with the fuel secondary combustion chamber; and an injection hole array is formed in the inner wall. The residence time and the turbulence degree of an oxidizing agent and fuel in the combustion chamber are increased, staged combustion is achieved, and the combustion efficiency of the engine is improved.

The invention discloses an air-cooled vortex control stabilizer, comprising an oil supply pipe, an evaporator pipe, a U-shaped gradually expanding blunt body and a stabilizer wall surface, wherein the oil supply pipe and the evaporator pipe are arranged in the U-shaped gradually expanding blunt body, the evaporator pipe is connected to the rear end wall and is provided with a mixed gas outlet hole, the air inlet nozzle is located on the arc front wall and is discretely arranged along the annular direction of the air-cooled vortex control stabilizer, the air inlet nozzle is connected to the evaporator pipe through an air inlet duct, the side wall of the air inlet duct is provided with an oil inlet connected to the oil supply pipe, the stabilizer wall surface is arranged on both sides of the rear end wall and includes a first wall surface and a second wall surface, each side wall surface is an annular groove structure composed of an inner wall surface and an outer wall surface, the opening is located on both sides of the rear end wall and is directly facing the incoming flow, a plurality of cooling holes are provided on the inner wall surface, a first air inlet hole with a larger aperture than the cooling hole is provided on the inner wall surface of the first wall surface close to the rear end surface, and the mixed gas outlet hole of the evaporator pipe faces the second wall surface. The invention can maintain flame stability and device durability when a high temperature rise phenomenon occurs in an afterburner.

The invention relates to the technical field of milling cutters, in particular to a wind driven generator rotor magnetic steel ladder groove machining milling cutter which comprises a milling cutter disc, a driving shaft and a first conveying unit. A plurality of groups of mounting grooves are formed in the outer edge of the milling cutter disc, and a cutting assembly is arranged in each group of mounting grooves. The cutting assembly comprises a cutting edge, the cutting edge is provided with a cutting face, and the cutting face is provided with a cutting end used for executing the cutting action. And when the driving shaft drives the milling cutter disc to axially rotate around the milling cutter disc, the cutting end starts deep groove machining immediately. After the cutting fluid in the containing cavity flows into the first flow channel, the first conveying unit can guide the cutting fluid to stably flow to the cutting end, so that the cutting end and the area, making contact with a workpiece, of the cutting fluid are efficiently cooled and lubricated. Therefore, through guiding of the first conveying unit, the flowing path of the cutting fluid on the cutting face is prolonged, the residence time of the cutting fluid on the cutting face and the cutting end is prolonged, efficient cooling and lubricating are achieved, the cutting temperature is remarkably reduced, and heating and abrasion of the cutting edge are reduced.

The present invention belongs to the field of biomedicine technology, and specifically relates to an umbilical cord mesenchymal stem cell, a preparation method thereof, and an application in treating myocardial infarction. The present invention provides an umbilical cord mesenchymal stem cell, which secretes a specific exosome, wherein the exosome contains a fusion protein, wherein the fusion protein is formed by the fusion of a peptide targeting ischemic myocardial tissue and an exosome transmembrane protein CD9, and is anchored on the surface of the exosome, thereby ensuring that the exosomes secreted by the umbilical cord mesenchymal stem cell have stronger targeting and activity. The present invention also provides a method for preparing umbilical cord mesenchymal stem cells, and further, the umbilical cord mesenchymal stem cells prepared by the present invention are used to prepare a drug for the treatment of myocardial infarction.

The invention provides a rapid cooling Dewar assembly. The rapid cooling Dewar assembly comprises a Dewar shell, a cold finger and a cold disc, wherein the cold finger and the cold disc are arranged in the Dewar shell; the cold finger comprises a cold finger air cylinder backflow section and a cold finger air cylinder cold end, the cold finger air cylinder cold end is in a conical funnel shape, the small-caliber end of the cold finger air cylinder cold end is connected with the cold finger air cylinder backflow section, and the cold disc is installed at the large-caliber end of the cold finger air cylinder cold end. According to the Dewar assembly, the cold end of the cold finger air cylinder is designed to be of the conical funnel structure, the fluid disturbance of cold fluid at the cold end is increased through the structural design, the residence time of the cold fluid in the cold finger is prolonged, and therefore the cooling capacity of the cold fluid can be fully utilized, heat exchange between the cold fluid and the cold disc is enhanced, and the cooling effect of the Dewar cold head is improved.

The utility model provides an electric field driven liquid-liquid multiphase reactor based on a fluidized bed. The electric field driven liquid-liquid multiphase reactor comprises a reactor body, a mesh partition plate, inert particles, a first electrode, a second electrode and a controller, the mesh partition plate is mounted at the lower part of the reactor body, a cavity above the mesh partition plate in the reactor body is a reaction area, and the inert particles are distributed in the reaction area. The first electrode and the second electrode are respectively arranged on two sides of the inner wall of the reactor body, are positioned in the upper reaction area, and are respectively and electrically connected with the positive electrode and the negative electrode of the high-voltage power supply. And the high-voltage power supply is connected with the controller. According to the utility model, electric field force is utilized to apply acting force to charged liquid drops, the liquid drops are driven to generate violent collision and shearing action in the fluidized bed, and mass transfer and reaction between liquid and liquid are promoted. Meanwhile, the electric field force can also control the movement of the liquid drops, so that the reaction process is strengthened and controlled.

The application provides a kind of superparamagnetic micro-particle based on microbial template, the mass ratio of cobalt element and iron element in superparamagnetic micro-particle is (1-5):1;The content of iron element in superparamagnetic micro-particle is 18-75 mg / g, and the content of cobalt element is 18-375 mg / g.Simultaneously, the application also provides the preparation method and application of the superparamagnetic micro-particle.The superparamagnetic micro-particle can effectively load antigen protein, and then induce the body to produce long-term, efficient specific immune response, improve the protection ability, and can be applied to the preparation of vaccine adjuvant.

The invention discloses an itching-relieving gel containing 3-hydroxydecanoic acid microemulsion and a preparation method thereof, the gel combines natural itching-relieving components 3-hydroxydecanoic acid and peppermint essential oil, the natural itching-relieving components 3-hydroxydecanoic acid and peppermint essential oil are prepared into a microemulsion form, nanoscale liquid drops are compounded with a skin-promoting absorbent, and the gel is slowly released, so that the itching-relieving effect is achieved. Therefore, the percutaneous absorption efficiency is improved, the residence time in the skin is prolonged, and a lasting itching relieving effect is realized; 3-hydroxydecanoic acid exerts an itching relieving effect through an anti-inflammatory effect, blocking of an itching signal channel and reduction of mast cell degranulation, and the itching relieving gel is stable at room temperature, convenient to use and suitable for relieving mosquito bites and skin itch problems caused by histamine or non-histamine substances and the like.

The invention relates to the technical field of carbon dioxide capture, in particular to a porous medium spiral microchannel carbon dioxide adsorbent carrier. Comprising a carrier body; the carrier body is of a honeycomb structure, a plurality of airflow micro-channels spirally extending in the axial direction are formed in the carrier body, the screw pitch of each airflow micro-channel is 5-7 cm, and the aperture of each airflow micro-channel is 5-10 mm; a carbon dioxide adsorbent is loaded in the carrier body. The porous characteristic of the carbon dioxide adsorbent carrier can increase the contact area of the adsorbent and gas, and the carbon dioxide adsorption efficiency is improved. And the spiral structure can prolong the gas flow path and strengthen the rotational flow effect, so that the adsorbent is more fully contacted with the gas, and meanwhile, the design of the spiral channel is beneficial to uniform transfer of heat and improvement of the desorption efficiency.

The invention discloses a buffer flow control and replacement management method and system supporting software marking, and the method comprises the steps: setting a programmable register at a software layer for software marking, and transmitting the software marking to a cache controller; a preceding-stage flow control arbiter receiving mark is added at the front end of a cache controller, the flow control priority score of each memory access request is dynamically calculated, and arbitration scheduling is carried out; a decoupling replacement strategy fusion engine is arranged in a cache controller, and a software mark and a hardware prediction replacement strategy are fused; consistency state co-processing is added in the cache replacement process, performance data during operation are collected through a performance monitoring module, a performance monitoring feedback path is provided and fed back to software, and a software mark in a programmable register is dynamically adjusted. According to the invention, through the data flow attribute marking, the preceding-stage flow control arbitration mechanism, the replacement strategy fusion engine and the consistency collaboration unit with software and hardware collaboration, the fine management of the data residence behavior in the cache system can be realized.

The application provides a front ring gas supply device for an ion thruster discharge chamber, comprising a gas supply ring groove and a gas supply ring cover, the gas supply ring groove and the gas supply ring cover cooperate to form a cavity, the cavity comprises a first cavity and a second cavity, a plurality of through holes are arranged on the gas supply ring cover, the first cavity and the second cavity are communicated through the through holes, the first cavity is communicated with a gas supply pipeline, and the second cavity is communicated with a discharge chamber cavity. By adopting the two-stage cavity buffer gas supply mode, the distribution of the working gas in the ion thruster discharge chamber is more uniform, the spatial uniformity of the plasma density in the ion thruster is improved, and then the flatness of the extracted ion beam is improved, which is beneficial to prolonging the service life of the ion thruster; by adopting the oblique gas injection mode, the axial velocity of the gas is reduced, the residence time of the working gas in the ion thruster discharge chamber is prolonged, and the working gas utilization rate of the ion thruster is improved.

The invention belongs to the technical field of energy storage equipment, and discloses an energy storage device, which comprises an energy storage device main body, a heat dissipation cabinet and a silencer, one side of the energy storage device main body is provided with a heat dissipation chamber, and the heat dissipation chamber is provided with a first mounting port; the silencer comprises an air guide piece and a silencing shutter, the silencing shutter comprises a frame, a plurality of blades and a reinforcing structure, the blades are connected with the reinforcing structure, the air guide piece is located between the heat dissipation cabinet and the frame, and the two sides of the air guide piece are tightly attached to the heat dissipation cabinet and the frame respectively so that an air guide channel can be defined between the air outlet and the blades; the air guide piece, the frame and the reinforcing structure are all filled with sound absorption pieces. The silencing shutters are matched with the air guide pieces, the space utilization rate of the silencer is increased, the size of the silencer is reduced, and the energy efficiency and the heat dissipation efficiency of the whole machine are improved.

The utility model relates to the field of kitchen utensils, and particularly discloses a pot support and a kitchen range. The energy gathering ring comprises an inner peripheral wall and an outer peripheral wall, the cross section of the inner peripheral wall is in a straight plate shape, and the cross section of the outer peripheral wall is in an arc shape protruding towards the outer peripheral side of the energy gathering ring. And the inclination angle of the inner peripheral wall relative to the vertical direction is not more than 20 degrees. The pot support is provided with the inner peripheral wall extending in the roughly vertical direction and the arc-shaped outer peripheral wall, so that a vortex area is formed near the roughly vertical inner peripheral wall on the inner side, the energy gathering effect is improved, and the effect of preheating secondary air in advance is achieved.

The invention discloses a polishing head with a viscoelastic fluid-polishing solution dielectrophoresis composite effect, which is characterized in that an insulating layer is arranged on the inner side of flexible polishing cloth, and a viscoelastic fluid is filled between the insulating layer and an amplification table; and a positive electrode and a negative electrode which can generate a non-uniform electric field after being matched for use are arranged in the insulating layer. When the polishing head works, a non-uniform electric field is generated, so that a polishing solution generates a dielectrophoresis effect, abrasive particles in the polishing solution are effectively prevented from flowing out of a machining area under the centrifugal force action of the polishing disc, the number of the abrasive particles is increased, the residence time of the abrasive particles in the machining area is prolonged, and the polishing efficiency and the polishing solution distribution uniformity are improved; the flexible deformation of the viscoelastic fluid enables the load of a processing area to be uniformly dispersed, so that the surface uniformity of a processed workpiece is improved, the problems of low surface type fitting capability and poor surface uniformity of a tool in curved surface polishing are solved, and meanwhile, the viscoelastic fluid responds to the vibration frequency to increase the viscosity and convert the viscosity into an elastic solid to provide the pressure required during polishing, so that the polishing efficiency is improved. And efficient removal of materials is guaranteed.

The application discloses a kind of microreactor for carbon dioxide conversion in air, including reaction cavity, and reaction cavity shell is made of light transmission glass;Multiple sets of catalyst carrier assemblies are equipped in reaction cavity cavity, along material flow direction, adjacent catalyst carrier assemblies are staggered in turn and form baffle passage;Each set of catalyst carrier assembly is composed of transversely arranged catalyst carrier and longitudinally arranged catalyst carrier;Catalyst carrier is foam ceramic carrier, and catalyst is loaded on carrier, and foam ceramic carrier is porous structure.The application limits reactor, can realize CO2 on foam ceramic carrier in reactor inside sufficient mass transfer and heat transfer, and transversely and longitudinally arranged carrier can increase the residence time of CO2 in foam ceramic pore, and transversely and longitudinally arranged carrier can expose more active sites of catalyst, so that the catalytic efficiency of entire reaction is improved, realizes CO2 100% conversion rate, and also can realize 100% conversion of CO2 in air.

This invention discloses a thermosensitive hydrogel loaded with anti-inflammatory small molecules, its preparation method, and its applications, relating to the field of biomedical technology. It comprises mesenchymal stem cell-derived exosomes loaded with anti-inflammatory small molecules, sodium hyaluronate, a thermosensitive hydrogel matrix, and an enzymatic debridement agent. This invention encapsulates papain with enzymatic debridement function, anti-inflammatory small molecules, and mesenchymal stem cell-derived exosomes as the main body of repair activity within a thermosensitive hydrogel matrix composed of a fixed ratio of poloxamer 407 and poloxamer 188. This composition is liquid at low temperatures, making it easy to apply, and transforms in situ into a semi-solid gel upon contact with oral temperature, achieving wound adhesion and long-term residence. Papain is used for initial debridement, creating conditions for subsequent repair; the bioaffinity between the anti-inflammatory small molecules and exosomes enables controlled and sustained release of the active ingredients; and finally, mesenchymal stem cell-derived exosomes promote wound repair.

The invention belongs to the field of new daily chemical materials, and discloses a hair care composition which is characterized in that the composition is an oil-in-water emulsion system; micelles in the oil-in-water emulsification system are coated with an oil-soluble hair care conditioner; the oil-in-water emulsification system also comprises glycerol, hydrolyzed sericin and hydrolyzed silk fibroin; the weight ratio of the glycerol to the hydrolyzed sericin to the hydrolyzed silk fibroin is 5: (0.004-0.02): (0.002-0.01). According to the composition, the residence time of the oil-soluble hair care conditioner is prolonged, and the conditioning effect is improved; meanwhile, the invention further provides application and cosmetics of the composition.

The invention discloses a plasma reaction device for mechanically assisting catalyst fluidization. A reaction cavity of the plasma reaction device is composed of an inner medium tube, an outer medium tube, two ground electrodes and a high-voltage electrode, the first ground electrode, the outer dielectric tube, the high-voltage electrode, the inner dielectric tube and the second ground electrode are arranged from outside to inside to form a reaction cavity; a sealing device is arranged at a port of the outer medium pipe, and a motor in the sealing device is connected to a head port of the inner medium pipe through a transmission device to drive the inner medium pipe, the high-voltage electrode and the second ground electrode to rotate around a straight line where the central axes of the inner medium pipe, the high-voltage electrode and the second ground electrode are located; gas enters the inner medium pipe through the gas inlet hole in the sealing device and enters the reaction cavity, namely, the gas enters the inner medium pipe through the gas inlet hole, enters the cavity between the inner medium pipe and the outer medium pipe through the tail end of the inner medium pipe and finally flows out from the gas outlet hole in the head of the outer medium pipe. The gas treatment efficiency is improved, meanwhile, the problem that discharge is weakened due to the fact that the catalyst adheres to the wall is solved, and the energy utilization efficiency and the synergistic effect are remarkably improved.

The invention discloses an inclined jet circulation interstage combustion chamber and low-pressure turbine guide vane coupling test device, and relates to the technical field of aero-engine experiment devices, the inclined jet circulation interstage combustion chamber and low-pressure turbine guide vane coupling test device comprises a combustion chamber test section and a guide vane test section, and inner and outer casings of the guide vane test section and the combustion chamber test section are fixedly connected through flanges and screws; the other end of the guide vane test section is fixedly connected with the tail gas section through a flange and a screw. According to the inclined-spraying circulation interstage combustion chamber and low-pressure turbine guide vane coupling test device, the oil spraying piece extends into the flame tube at a certain angle to supply oil, and the inclined holes are formed in all parts of the flame tube to supply air, so that the residence time of fuel in the combustion chamber is prolonged, the combustion efficiency is improved, and the design concept of the interstage combustion chamber of pneumatic organization is realized; and a temperature sensor, a pressure sensor and a flue gas analysis device are arranged for data collection, and the method has important significance for analyzing related performance indexes of coupling of the oblique-spraying circulation interstage combustion chamber and the low-pressure turbine guide vane.

The application relates to the technical field of traditional Chinese medicine preparations, and specifically discloses a wet eczema external washing formula and a preparation method thereof. The wet eczema external washing formula is composed of three raw medicinal materials, namely, Sophora flavescens, Fructus Mume and Smilax glabra. The preparation method is as follows: low-temperature segmented extraction of Fructus Mume is performed to obtain an acidic extract and residues; a part of the acidic extract is used to pretreat the residues, and then enzymolysis is performed to obtain a directional polysaccharide extract; the remaining acidic extract is used to extract Sophora flavescens and Smilax glabra; the extract and the polysaccharide extract are combined at a controlled speed to construct a non-covalent compound; after nitrogen protection, segmented concentration and low-temperature curing and shaping, the product is obtained through filling, sterilization and the like. The wet eczema external washing formula can be used for wet eczema external washing treatment, active ingredients can form a sustained-release colloid network, the skin residence time is prolonged, and the antipruritic and anti-inflammatory effects are long-lasting. In the preparation method, no exogenous acid and alkali and no chemical stabilizer need to be introduced, resource closed-loop utilization in the formula is realized, the dissolution rate of active ingredients and the stability of the preparation are high, the process controllability is good, and the preparation method is suitable for industrialized production.

The invention provides a micro-miniature non-premixing burner based on a concave-convex wall structure, and relates to the technical field of micro-scale thermo-photoelectric capability conversion, the micro-miniature non-premixing burner comprises a burner outer wall, a porous medium is arranged on the inner side of the burner outer wall, and two groups of concave-convex walls arranged in a stacked manner are mounted on the inner side of the burner outer wall; the inner portion of the burner outer wall is divided into a first air inlet channel, a second air inlet channel and an air outlet channel by the two sets of concave-convex walls, the first air inlet channel and the second air inlet channel are symmetrically arranged on the two sides of the air outlet channel, the first air inlet channel and the second air inlet channel are both communicated with the porous medium, and the porous medium is communicated with the air outlet channel. The gas outlet channel comprises a combustion chamber, a bluff body and a gas outlet which are sequentially communicated; the combustion efficiency of the combustor can be improved, the combustion stability is enhanced, the heat loss is reduced, and the high-temperature environment and uniform temperature distribution are maintained.