81488 results about "Chemical engineering" patented technology

The invention discloses a method for continuously and efficiently adsorbing and separating hydrogen isotopes. The hydrogen isotopes are separated by adopting a multi-tower variable-temperature variable-pressure device operated in a simulated moving bed operation mode. When the device runs, each adsorption tower needs to sequentially execute the following steps: 1, adsorption; 2, replacement; 3, heating; 4, vacuumizing and desorbing; 5, carrying out vacuum purging; 6, pressurizing and cooling; the operation mode of the simulated moving bed is that an adsorption tower is frequently, sequentially and synchronously moved along the gas flowing direction in the tower through all gas input and output ports, so that an adsorbent phase and a gas flowing phase in the tower form countercurrent flow, and the hydrogen isotope adsorption separation efficiency is enhanced. The invention relates to a technological process of cyclic adsorption, replacement, heating, vacuum desorption, pressurization and cooling, continuous and efficient hydrogen and isotope adsorption separation is realized, multi-tower serial adsorption and replacement are adopted in the process, and separation of hydrogen isotopes (such as H2 / D2) is enhanced; and the desorption efficiency of heavy components is improved by adopting a heating and vacuumizing depressurization coupling mode.

This invention discloses a fluorene-based organic small molecule hole transport material and its applications. The general structural formula of the fluorene-based organic small molecule hole transport material is as follows: where n = 1-4, and R represents the hole transport capacity. This fluorene-based organic small molecule hole transport material is used as an undoped hole transport material in perovskite solar cell devices. By introducing dicarboxylic acid groups onto the fluorene-based organic small molecule hole transport material, when used in an inverted perovskite solar cell device, it can form chemical bonds with the hydroxyl groups of the glass conductive substrate, forming a directionally aligned self-assembled layer on the surface of the glass conductive substrate. This effectively improves the charge transport capability at the interface and increases the photoelectric conversion efficiency of the perovskite solar cell device. Furthermore, since this perovskite solar cell device does not contain lithium salts, it exhibits high water and oxygen stability. In addition, the synthesis process of this fluorene-based organic small molecule hole transport material is simple, and the raw materials are inexpensive and readily available, making it highly valuable for practical applications.

A reactor system includes a reactor that treats a lipid feedstock using a metal oxide catalyst to produce a treated stream comprising a bio-oil. The reactor system includes a catalyst zone in which the metal oxide catalyst reacts with the lipid feedstock to produce the treated stream. The reactor system operates in a reaction mode, during which the lipid feedstock flows in a downward direction through the metal oxide catalyst to produce the treated stream. Alternately, the reactor also operates in a regeneration mode, during which coke is burned from the metal oxide catalyst thereby regenerating the metal oxide catalyst. In one aspect, a regeneration mode pressure is less than a reaction mode pressure within the reactor to fluidize the catalyst.

Described herein are sorbents functionalized with polyamines having oxygen-containing units selected from carbonyl units, hydroxyl units, and combinations thereof, methods of making same, and methods of using same.

The invention provides a positive electrode, a low-temperature electrolyte, a low-temperature sodium-ion battery and a preparation method and application of the low-temperature sodium-ion battery, and belongs to the technical field of battery materials. The low-temperature sodium ion battery comprises a positive electrode, a negative electrode and a low-temperature electrolyte, wherein the positive electrode comprises a positive electrode active material, a binder, sodium salt containing fluorine and sulfur and conductive carbon; the positive electrode is improved by adding sodium salt containing fluorine and sulfur, sulfur / fluorine rich in anion derivatives can be formed on a contact interface of the positive electrode and an electrolyte to form a firm SEI film, the internal resistance of the battery is further reduced, and the coulombic efficiency of the battery during charging and discharging at normal and low temperatures is improved. The low-temperature electrolyte comprises an ester solvent and an ether additive, by adding the ether solvent, the physicochemical property of the electrolyte and the composition of an SEI film on a contact interface of an electrode and the electrolyte are optimized, the viscosity of the electrolyte at low temperature is reduced, the ionic conductivity is improved, and formation of the SEI film rich in sodium fluoride on the surface of a negative electrode can be promoted; and thus, the problem of low coulombic efficiency of battery charge-discharge cycle at low temperature is solved.

A long-term fire retarding biochemical liquid composition including: a dispersing agent realized in the form of a major amount of water, for dispersing alkali metal ions dissolved in the water; a major amount of a first fire retarding agent realized in the form of a primary alkali metal salt of a nonpolymeric saturated carboxylic acid, for example, tripotassium citrate, for providing metal potassium ions dispersed in the water when the at least one alkali metal salt is dissolved in the water to form a mixed retardant solution; a minor amount of a second fire retarding agent realized in the form of a secondary alkali metal salt of a nonpolymeric saturated carboxylic acid, for example, potassium, sodium, calcium and / or magnesium benzoate, for providing benzoate ions dispersed in the water when the secondary alkali metal salt is dissolved in the mixed retardant solution, for functioning as a secondary fire retardant agent.

The invention discloses an asphalt-based hard carbon material as well as a pre-oxidation preparation method and application thereof. Belongs to the technical field of asphalt-based hard carbon materials. The pre-oxidation preparation method comprises the following steps: carrying out primary pre-oxidation treatment on asphalt at 250-400 DEG C in air flow of 50-500mL / min; crushing the obtained primary pre-oxidized asphalt, and then carrying out secondary pre-oxidation treatment at 250-400 DEG C in air flow of 50-500mL / min to obtain secondary pre-oxidized asphalt; and carrying out carbonization treatment on the secondary pre-oxidized asphalt. According to the method, the asphalt can be kept in a solid-phase state to be subjected to efficient and thorough oxidation cross-linking reaction, the production cost is reduced, the obtained asphalt-based hard carbon material has high first coulombic efficiency and high capacity, and powerful support is provided for commercial application of sodium-ion battery negative electrode materials and rapid development of an energy storage technology.

The invention discloses a sulfuric acid erosion resistant self-repairing geopolymer system and a self-repairing method thereof, and relates to the technical field of composite materials and artificial intelligence. At least one self-repairing unit optimized for sulfuric acid erosion embedded within the geopolymer matrix; the in-situ multipoint pH sensing network is integrated in the geopolymer matrix and is used for monitoring spatio-temporal evolution data of a pH field in a sulfuric acid erosion process in real time; the edge calculation module is used for identifying a preliminary erosion indication according to the received spatio-temporal evolution data of the pH field; and the central AI decision module is used for evaluating an erosion state and predicting a development trend by utilizing an AI model optimized aiming at sulfuric acid erosion according to the identified preliminary erosion indication and the pH field spatio-temporal evolution data, and generating an optimal repair strategy to control the self-repair unit to perform self-repair. According to the invention, intelligent, active and refined protection and life management of the geopolymer in the sulfuric acid erosion process can be realized.

A process for upgrading plastic derived oil includes contacting the plastic derived oil with a mixed catalyst in a first reactor, where the mixed catalyst includes a decontamination catalyst and a cracking catalyst different from the decontamination catalyst. The first reactor reduces concentrations of halogen-containing compounds in the plastic derived oil. The process includes passing the first reactor effluent to a second reactor and contacting the first reactor effluent with the cracking catalyst to produce a second effluent comprising light olefins and naphtha range hydrocarbons. The process includes separating used mixed catalyst from the first reactor to produce a used decontamination catalyst and a second used cracking catalyst, and regenerating the decontamination catalyst and cracking catalyst in separate regenerators to reduce exposure of the cracking catalyst to halogen-containing compounds produced during regeneration of the used decontamination catalyst.

The invention discloses a zinc-iodine battery positive electrode material based on corn straw shell derived porous carbon and a preparation method of the zinc-iodine battery positive electrode material. According to the material, corn straw shells serve as the sole carbon source, an indigenous nitrogen-doped biomass charcoal carrier with a hierarchical pore structure is prepared through pre-carbonization and KOH activation processes, and the material is characterized in that the specific surface area is larger than or equal to 1500 m < 2 > / g, and the micropore proportion is larger than 90%. The iodine is loaded on the carrier (the iodine content is greater than or equal to 45wt%) through a vacuum sublimation method to form the indigenous nitrogen-doped biomass charcoal / iodine composite material. According to the positive electrode material, through the synergistic effect of physical confinement and pyridine nitrogen chemical adsorption, the multi-iodide shuttle effect is effectively inhibited, so that the capacity retention rate of the zinc-iodine battery is greater than or equal to 93% after 40000 cycles under the current density of 2A g <-1 >, and the capacity retention rate is greater than 45% under the rate of 10A / g. The method has double benefits of agricultural waste resource utilization and high-performance energy storage device development.

The invention discloses a modified graphite felt electrode for an all-vanadium redox flow battery and a preparation method of the modified graphite felt electrode, and belongs to the technical field of redox flow battery electrode materials. The preparation method comprises the following steps: graphite felt electrochemical oxidation etching treatment; self-assembling a conductive layer on the oxidized and etched graphite felt to obtain the graphite felt attached with the conductive layer; and loading a metal and nitrogen-doped carbon (M and NC) nano catalyst layer on the graphite felt attached with the conductive layer to obtain the modified graphite felt electrode. Various properties of the graphite felt are comprehensively improved through matrix treatment, structure change and load catalysis, mild electrochemical oxidation etching is adopted, a carbon fiber structure is protected, a self-assembled net-shaped conductive layer forms a stable conductive channel, the specific surface area is remarkably increased, a nitrogen-doped carbon shell is adopted to wrap metal nanodots to form an M-NC catalytic layer, and the specific surface area is remarkably increased. The catalyst layer is not easy to dissolve out, the capacity fading rate is obviously improved, the loading capacity of the catalyst layer on the reticular structure conducting layer with a larger specific surface area is larger, and meanwhile, the process is simple and low in cost.

A direct air capture (DAC) of CO2 system includes a reaction reactor having a solid, amine-functionalized sorbent configured to sequester CO2 from air; an in-situ dual-function device configured as a CO2 conversion reactor and an exchange fluid regeneration device; and the exchange fluid, recirculating between the reaction reactor and the dual-function device, configured to capture the sequestered CO2 from the solid sorbent in the reaction reactor and release the captured CO2 in the conversion reactor, the exchange fluid including one or more amino acids.

The invention relates to the technical field of high-entropy oxide and electrocatalyst synthesis, in particular to a double-phase hollow high-entropy oxide catalyst and a preparation method and application thereof, the double-phase hollow high-entropy oxide catalyst comprises metal elements and non-metal elements, the metal elements comprise ruthenium, nickel, cobalt, iron, manganese and chromium; the non-metallic element is oxygen; the chemical formula of the double-phase hollow high-entropy oxide catalyst is NiCoFeMnCrRuO. The invention further discloses a preparation method of the catalyst. The double-phase hollow high-entropy oxide catalyst has a multi-shell hollow structure, provides a larger specific surface area and exposes a large number of reaction active sites, so that the double-phase hollow high-entropy oxide catalyst has lower overpotential, higher reaction efficiency and good electrochemical stability; meanwhile, the preparation method of the double-phase hollow high-entropy oxide catalyst is simple in process, low in cost, high in repeatability and suitable for industrial mass production, and has a wide application prospect.

The present invention relates to the technical field of carbon source preparation, and specifically relates to a carbon source preparation apparatus with a concentration detection function. The carbon source preparation apparatus comprises a frame, a tank body, a stirring system and a detection system, wherein the tank body is fastened and connected to the frame, the tank body being used for dissolution and chain-breaking of kitchen waste slurry; the stirring system is fastened and connected to the tank body; and the detection system is fastened and connected to the stirring system, a built-in sensor of the detection system being used for detecting the carbon source concentration. A heating pipe is provided on the outer side of the tank body, the heating pipe being externally connected to a heat source; the heating pipe maintains the temperature inside the tank body within an appropriate range to ensure the smooth progress of a reaction process, and the heating pipe enables evaporation and concentration of liquid after the reaction is complete. The detection system allows for online real-time monitoring of the carbon source concentration, such that during concentration of a carbon source, the process can be stopped in a timely manner when it is determined that the required concentration is reached after concentration and evaporation for a period of time, thereby reducing energy consumption.

The invention discloses a biomass charcoal composite hydrogel slow-release fertilizer as well as a preparation method and application thereof, and belongs to the field of composite hydrogel and fertilizer preparation. The invention provides a biomass charcoal composite hydrogel slow release fertilizer, which comprises biomass charcoal, hydrogel fixed on the pores and surface of the biomass charcoal, and an element fertilizer mixed in the hydrogel, and the hydrogel is prepared from metal cations and alginate. The invention provides a strategy of'in-hole in-situ gelation ', hydrogel is prepared in situ in gaps of the biochar, and the biomass charcoal composite hydrogel slow-release fertilizer is prepared. The biochar and the hydrogel in the slow-release fertilizer are high in bonding strength and mechanical strength, so that the slow-release fertilizer has the slow-release function of the fertilizer and also has the capability of improving soil.

The invention relates to the technical field of batteries, in particular to a solid electrolyte material and a preparation method thereof, a solid electrolyte membrane and a battery. The solid electrolyte material has a core-shell structure, the core-shell structure comprises an inner core and a coating layer arranged on the surface of the inner core, the inner core comprises a sulfide electrolyte, and the coating layer comprises an amide compound. According to the solid electrolyte material disclosed by the invention, the coating layer containing the amide compound is arranged on the surface of the sulfide electrolyte, so that the air stability of the solid electrolyte material can be effectively improved, and meanwhile, the solid electrolyte material is ensured to have proper conductivity without influencing the charge-discharge performance of a battery.

The invention discloses a method for promoting dissolution of eggshell membrane protein and preparing chelated calcium through high-pressure crushing. Comprising the following steps: separating and drying eggshells and eggshell membranes of egg shells, and respectively carrying out superfine grinding to obtain eggshell powder and eggshell membrane powder; adding water into the eggshell membrane powder, carrying out high-pressure homogenization, and centrifuging to obtain an eggshell membrane solution; adding eggshell powder into the eggshell membrane solution, adjusting the pH value to 1-3, and adding pepsase for reaction; after the reaction, adjusting the pH value of the eggshell membrane solution to 6.5-7.5, and adding trypsin for reaction; and after the reaction, inactivating the enzyme, centrifuging to take a supernatant, adding absolute ethyl alcohol into the supernatant for alcohol precipitation, and centrifuging to obtain a precipitate, namely the chelated calcium. The technical problem that the eggshell membrane protein is difficult to dissolve out is solved, and a new way is provided for industrial extraction of the eggshell membrane soluble protein.

The invention relates to a stable silk fibroin liquid condensation body, gel and a preparation method and application thereof, and belongs to the technical field of silk fibroin. The preparation method comprises the following steps: S1, dissolving silk fibroin in a lithium bromide solution, and then adding trypsin for incubation to obtain an enzyme-digested silk fibroin solution; and S2, performing low-temperature programmed centrifugal treatment including an induction stage, a nucleation stage and a liquid-liquid phase separation stage on the enzyme-digested silk fibroin solution, and cleaning to obtain the stable silk fibroin liquid-state aggregate, the method can reduce aggregate liquid drop aggregation and improve the particle size uniformity of the liquid drops.

The invention belongs to the technical field of data processing, and particularly relates to a rutile type titanium ore prospecting model construction method. Comprising the following steps: collecting remote sensing time sequence, real-time geophysical prospecting and geochemical data, carrying out geological causal feature analysis after standardization so as to construct a metallogenic causal graph, and meanwhile, collecting anti-fact features to generate virtual mineralization feature vectors; a prospecting model comprising an input layer, a weight optimization layer (comprising a causal attention module and a particle swarm anti-fact comparison module) and a mineralization probability output layer is constructed, and a high-frequency data acquisition mechanism is triggered with assistance of a metallogenic event threshold. According to the method, the data reliability and the model generalization ability are improved, the mineralization probability calculation precision and the potential mineralization target region judgment accuracy are remarkably improved, and a scientific support is provided for efficient prospecting of rutile type titanium ore.

The invention belongs to the technical field of cell cryopreservation, and relates to a cryopreservation method based on ultrasonic ice planting. In the method, the nucleation temperature of ice planting is less than-9 DEG C, and the cooling rate from nucleation to icing is less than 5 DEG C / min. Compared with the prior art, the method has the advantages that the time required for cryopreservation of the cells is remarkably shortened, meanwhile, damage to the cells caused by ice crystals generated in the cooling process is reduced, and the problem that an existing cell cryopreservation cooling method cannot meet the nucleation and freezing uniformity of a cell solution in the cooling process is solved.

The invention relates to the technical field of tail gas treatment, and provides a tail gas denitration reactor for hydrogenation catalyst production, the tail gas denitration reactor comprises a treatment box and an adsorption shell mounted in the treatment box, one end of the adsorption shell is connected with a gas inlet pipe, the other end of the gas inlet pipe is connected with a gas outlet pipe, and two ends of the adsorption shell are provided with a plurality of connecting grooves; the upper end of the adsorption shell is connected with a first connecting frame and a second connecting frame. The two ends of the first gas filtering bin and the two ends of the second gas filtering bin are meshed and installed on the gear shaft, so that the gear shaft drives the first gas filtering bin and the second gas filtering bin to rotate, the first gas filtering bin and the second gas filtering bin alternately conduct tail gas adsorption work, and in the standby replacement process, the filter elements in the first gas filtering bin and the second gas filtering bin are cleaned; the device can adsorb tail gas in a long-term and high-quality mode, the problems that the filter element is blocked and the adsorption effect is reduced due to long-time use of the filter element are solved, and environment-friendly emission of the tail gas can be achieved in the hydrogenation catalyst production and manufacturing process.

Provided is a laminate capable of electrolyzing an oxygen compound gas represented by CO2 with high conversion efficiency and suppressing deterioration in electrolytic performance. In this laminate having a structure in which an electrolyte layer is sandwiched between an anode catalyst layer and a cathode catalyst layer, a perovskite oxide and CuFe2O4 are contained in the cathode catalyst layer, and the content of CuFe2O4 in the cathode catalyst layer is at least 10 mass%.

The invention provides a solid electrolyte slurry, an electrode slurry, a solid electrolyte sheet, an electrode sheet, a solid battery monomer, a battery device and a power utilization device.The solid electrolyte slurry comprises a sulfide solid electrolyte material, a solvent and a binder dissolved in the solvent, and the solvent is a non-polar solvent, a weak-polar solvent or a mixed solvent of the non-polar solvent and the weak-polar solvent; the binding agent comprises a polyacrylate binding agent and a non-polar polyolefin binding agent. The slurry disclosed by the invention has high dispersity, high suspension property and good cohesiveness, and can enable the solid-state battery monomer to have high initial coulombic efficiency when being used in the solid-state battery monomer.

The preparation method comprises the following steps: S1, mixing a hydrochloric acid solution with organic sodium sulfonate, then adding aniline and water, stirring and dissolving, then adding an oxidizing agent to carry out doping reaction, and carrying out suction filtration, washing, drying and grinding on a reaction product to obtain sodium-modified polyaniline; s2, uniformly mixing a negative electrode active material, a conductive agent and polytetrafluoroethylene, and then adding sodium polyaniline and an organic sodium supplement agent in a nitrogen or inert atmosphere for fibration treatment to obtain fibration powder; and S3, performing hot pressing on the fiberized powder onto the current collector to obtain the lithium ion battery. The prepared pre-sodium-modified negative electrode dry-method electrode has relatively good peeling strength and pole piece flexibility, and the condition that a traditional wet-method thick electrode is easy to crack is relieved; meanwhile, the dry-method electrode subjected to sodium modification treatment can induce uniform deposition of sodium ions, so that the dynamic performance of the whole sodium battery is improved, the problem of cyclic sodium precipitation is avoided, and the service life of the battery is further prolonged.

The invention discloses a desalting membrane as well as a preparation method and application thereof, and relates to the technical field of membrane separation. The desalting membrane comprises a porous ultrafiltration base membrane and a functional layer formed on the surface of the porous ultrafiltration base membrane; the functional layer is formed by copolymerizing and cross-linking a polyamine monomer, a zwitterionic multi-element hydroxyl monomer and an acyl chloride monomer through an interfacial polymerization reaction. The preparation method comprises the following steps: providing the porous ultrafiltration base membrane; coating the surface of the porous ultrafiltration base membrane with an alkaline water-phase solution containing a polyamine monomer and a zwitterionic multi-hydroxyl monomer to form a water-phase solution layer; coating an oil-phase solution containing an acyl chloride monomer on the surface of the water-phase solution layer to form a functional layer; and performing heat treatment. The invention also provides application of the desalination membrane in any one of seawater desalination, brackish water desalination, wastewater treatment and material separation and concentration. According to the invention, zwitter-ion-based multi-hydroxyl monomers are introduced into water-phase monomers to participate in interfacial polymerization, and a super-hydrophilic nano-channel is constructed in a separation layer, so that the water flux and the desalination rate of the membrane are remarkably improved.

The invention relates to an iridium dioxide catalyst and a preparation method and application thereof, the iridium dioxide catalyst is a material with a three-dimensional porous structure, and the three-dimensional porous structure comprises mesopores and macropores; the characteristic peak of rutile type iridium dioxide exists in the XRD spectrogram of the iridium dioxide catalyst. When the catalyst disclosed by the invention is used as an anode catalyst in water electrolysis hydrogen production, the loading capacity of the catalyst can be effectively reduced, the dispersity is improved, and meanwhile, the catalyst has better mass transfer effect and conductivity, higher catalytic activity and excellent stability.

An iridium-based catalyst, wherein iridium in the catalyst is in the form of crystalline iridium dioxide. Relative to the catalyst as a whole, the content of the iridium element by mass fraction is greater than 70%, and the apparent mass-to-volume ratio of the catalyst is not higher than 0.55 g / cm3. The catalyst has a large specific surface area, a high porosity, and a low apparent mass-to-volume ratio, and therefore has excellent mass transfer performance and apparent catalytic activity. A three-dimensional porous structure of the catalyst can improve the utilization rate of the iridium element, so that the loading capacity of iridium in a membrane electrode is reduced, and the catalyst has excellent stability. The provided preparation method is simple, convenient, and highly economical.

The invention provides a ternary precursor and a preparation method thereof, a positive electrode material and a preparation process thereof, and a battery. The ternary precursor comprises an inner core, and a transition layer and a shell which are sequentially coated outside the inner core, the nickel content of the inner core is gt; the nickel content of the transition layer is gt; and the nickel content of the shell. The inner core in the ternary precursor has the highest nickel content, so that the capacity of the positive electrode material prepared from the ternary precursor is ensured; the nickel contents of the inner core, the transition layer and the shell are changed in a gradient manner, so that the thermal stability of the ternary precursor is improved; the shell reduces the interface side reaction between the positive electrode material prepared from the ternary precursor and an electrolyte; the transition layer can be used as a buffer layer between the inner core and the shell, so that the ternary precursor and the structural stability are improved. Therefore, the battery containing the positive electrode material prepared from the ternary precursor has excellent capacity and cycling stability at normal temperature and high temperature.

The invention relates to the technical field of crystal material preparation, in particular to a ternary layered selenide Ge3Sb4Se7 semiconductor material and a preparation method thereof. The preparation method of the ternary layered selenide Ge3Sb4Se7 semiconductor material comprises the following steps that S001, germanium powder, antimony powder and selenium powder with the molar ratio being 3: 4: 7 serve as raw materials, the temperature is increased to 900-950 DEG C under the vacuum condition, and heat preservation is conducted for 12-24 h at the temperature; s002, after heat preservation is finished, the temperature is reduced to 475-500 DEG C at the cooling rate of 1-5 DEG C / min, and heat preservation is conducted for 3-5 days at the temperature; and after heat preservation is finished, furnace cooling or quenching cooling is performed to reach the room temperature, and the layered ternary selenide single-phase material with the chemical formula being Ge3Sb4Se7 is obtained. The ternary layered selenide Ge3Sb4Se7 semiconductor material prepared by the invention is a single-phase material and has the characteristics of low thermal conductivity and low resistivity, so that the ternary layered selenide Ge3Sb4Se7 semiconductor material has application potential in the fields of thermoelectric devices, photoelectric detection and the like.

The invention relates to a solid electrolyte coated silicon-carbon negative electrode material and a preparation method thereof, an all-solid-state battery and an electric device, and belongs to the technical field of methods or devices for directly converting chemical energy into electric energy. The solid electrolyte coated silicon-carbon negative electrode material comprises a silicon-carbon negative electrode material and a solid electrolyte coating layer arranged on the surface of the silicon-carbon negative electrode material, the solid electrolyte coating layer comprises at least one of sulfide electrolyte and halide electrolyte; the silicon-carbon negative electrode material comprises an inner core and a carbon coating layer arranged on the surface of the inner core, the inner core comprises a porous carbon matrix and a silicon-based material positioned in pores of the porous carbon matrix. The solid-state electrolyte coated silicon-carbon negative electrode material enables an all-solid-state battery to have high ionic conductivity and first efficiency and excellent cycling stability.