Self-adjusting rapid titration control method, system, equipment and medium considering chemical reaction lag

Abstract

The invention discloses a self-adjusting rapid titration control method, system, equipment and medium considering chemical reaction lag, and the method comprises the following steps: dividing a plurality of continuous gradient intervals, different gradient intervals corresponding to different dosing time and dosing rate; in the titration process of the solution, the color value of the solution is measured at intervals of prediction time; calculating the current gradient according to the measured color value of the solution, judging the gradient interval to which the current gradient belongs, determining the dosing time and dosing rate according to the judged gradient interval, and titrating the solution according to the determined dosing time and dosing rate, the method, the system, the equipment and the medium can realize automatic and accurate control of titration.

Description

Technical Field

[0001] The invention belongs to the field of chemical analysis and relates to a self-regulating rapid titration control method, system, equipment and medium taking into account chemical reaction hysteresis. Background Art

[0002] Titration analysis is a fast, simple and widely used quantitative analysis method. The core of titration analysis is to precisely control the amount of titrant added, so that the substance being measured reacts quantitatively with the titration solution according to a specific reaction process, thereby achieving the purpose of measuring the content of the substance being measured. However, in actual application, the accuracy and efficiency of titration analysis are often restricted by many factors, such as the hysteresis of chemical reactions and the control accuracy of dosing mechanisms.

[0003] Defects and shortcomings of the existing technology:

[0004] 1. Insufficient control accuracy: The method [A dual-wavelength automatic control method and device for rapid photometric titration [P]. Zhang Huan, Cheng Guangjiao. Chinese patent: CN106198532A, 2018-09-04.] only provides two titration rates, "fast" and "slow". However, in actual applications, when the titration endpoint is about to be reached, the observed quantity will change suddenly. Only dividing the titration rate into two types cannot fully adapt to the entire titration process, which may lead to excessive titration. The accuracy can be further improved.

[0005] 2. Failure to consider the reaction hysteresis factor: Existing methods do not consider the hysteresis of the chemical reaction in the titration process. This hysteresis usually leads to excessive addition of the titration solution. Especially in reaction systems that require rapid and continuous monitoring, the hysteresis of the chemical reaction becomes the main factor restricting the efficiency of titration analysis.

[0006] 3. Lack of adaptive adjustment function: The traditional titration control system lacks adaptive adjustment capability and cannot be dynamically adjusted according to the real-time state of the reaction system. When the reaction conditions change (such as temperature fluctuations, concentration changes, etc.), the system cannot respond in time and make corresponding adjustments. Summary of the invention

[0007] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a self-adjusting rapid titration control method, system, equipment and medium taking into account the lag of chemical reaction, which can realize automatic and accurate control of titration.

[0008] In order to achieve the above object, the present invention adopts the following technical scheme:

[0009] In one aspect of the present invention, the self-regulating rapid titration control method considering chemical reaction hysteresis of the present invention comprises:

[0010] Dividing a number of continuous gradient intervals, wherein different gradient intervals correspond to different dosing times and dosing rates;

[0011] During the titration of the solution, the color value of the solution is measured at intervals of predicted time; the current gradient is calculated based on the measured color value of the solution, and the gradient interval to which the current gradient belongs is determined; the dosing time and the dosing rate are determined based on the determined gradient interval; and the solution is titrated based on the determined dosing time and dosing rate.

[0012] The self-regulating rapid titration control method considering the chemical reaction hysteresis of the present invention is further improved in that:

[0013] Furthermore, the continuous gradient intervals are divided into several continuous gradient intervals, wherein the dosing time and dosing rate of different gradient intervals are divided into continuous gradient intervals [a 1 , a 2 ), [a 2 , a 3 ), [a 3 , a 4 ) and [a 4 , +∞), where [a 1 , a 2 ) The corresponding dosing time and dosing rate are t 1 and V max ; [a 2 , a 3 ) The corresponding dosing time and dosing rate are t 2 and V normal ; [a 3 , a 4 ) The corresponding dosing time and dosing rate are t 3 and V min ; [a 4 , +∞) corresponds to the dosing time and dosing rate t 4 and V seq .

[0014] Furthermore, the gradient ΔR(n) is:

[0015]

[0016] Wherein, n=1, 2, ..., mm∈Z, Z represents a positive integer set, R(n) represents a color value detected for the nth time, and δ is the interval prediction time.

[0017] Furthermore, it also includes:

[0018] Calculate the cumulative dosage f as:

[0019] f=v max tmax +v normal t normal +v min t min +v max t max +

[0020] v seq (t seq -d τ (t,v)) (3-3)

[0021] In a second aspect of the present invention, the self-adjusting rapid titration control system considering the chemical reaction hysteresis of the present invention comprises:

[0022] A division module is used to divide a number of continuous gradient intervals, wherein different gradient intervals correspond to different dosing times and dosing rates;

[0023] The titration module is used to measure the color value of the solution at intervals of predicted time during the titration process of the solution; calculate the current gradient according to the measured color value of the solution, judge the gradient interval to which the current gradient belongs, determine the dosing time and dosing rate according to the judged gradient interval, and titrate the solution according to the determined dosing time and dosing rate.

[0024] The self-regulating rapid titration control system considering the chemical reaction hysteresis of the present invention is further improved in that:

[0025] Furthermore, the continuous gradient intervals are divided into several continuous gradient intervals, wherein the dosing time and dosing rate of different gradient intervals are divided into continuous gradient intervals [a 1 , a 2 ), [a 2 , a 3 ), [a 3 , a 4 ) and [a 4 , +∞), where [a 1 , a 2 ) The corresponding dosing time and dosing rate are t 1 and V max ; [a 2 , a 3 ) The corresponding dosing time and dosing rate are t 2 and V normal ; [a 3 , a 4 ) The corresponding dosing time and dosing rate are t 3 and V min ; [a 4 , +∞) corresponds to the dosing time and dosing rate t 4 and V seq.

[0026] Furthermore, the gradient ΔR(n) is:

[0027]

[0028] Wherein, n=1, 2, ..., mm∈Z, Z represents a positive integer set, R(n) represents a color value detected for the nth time, and δ is the interval prediction time.

[0029] Furthermore, it also includes:

[0030] Calculate the cumulative dosage f as:

[0031] f=v max t max +v normal t normal +v min t min +v max t max +

[0032] v seq (t seq -d τ (t,v)) (3-3).

[0033] In a third aspect of the present invention, the computer device of the present invention comprises a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the self-adjusting rapid titration control method taking into account the chemical reaction lag when executing the computer program.

[0034] In a fourth aspect of the present invention, the computer-readable storage medium of the present invention stores a computer program, and when the computer program is executed by a processor, the steps of the self-adjusting rapid titration control method considering the chemical reaction lag are implemented.

[0035] The present invention has the following beneficial effects:

[0036] In the specific operation of the self-adjusting rapid titration control method, system, equipment and medium taking into account the chemical reaction lag described in the present invention, different gradient intervals correspond to different dosing times and dosing rates. During the titration of the solution, the dosing time and dosing rate are controlled according to the gradient of different sampling periods, thereby avoiding various problems caused by a single dosing rate and realizing automatic and accurate control of the titration. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0038] Figure 1 It is a schematic diagram of the change of dosage and R / RGB;

[0039] Figure 2 is a flow chart of the method of the present invention;

[0040] Figure 3 Schematic diagram of the titration hysteresis experiment. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only an embodiment of a part of the present invention, not all embodiments, and is not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concepts disclosed in the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0042] The accompanying drawings show schematic diagrams of structures according to embodiments disclosed in the present invention. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0043] Embodiment 1

[0044] refer to Figure 1 The self-regulating rapid titration control method considering the chemical reaction hysteresis in this aspect comprises the following steps:

[0045] In the process of chemical titration analysis, the rate of change of solution color is not linearly related to the dosage, that is, when the dosage reaches a certain level, the solution color will suddenly change, such as Figure 1 shown.

[0046] Therefore, during the automatic titration process, if a single rate of change is always used, overdosage may occur and the titration endpoint may be missed.

[0047] 1) Titration rate self-switching method based on light-sensitive gradient;

[0048] Since the titration analyzer belongs to a type of computer control system, which is actually a discrete control system, each detection and control signal can be regarded as a discrete signal. Let the time interval between each color detection be δ, and the color value of the kth detection be R(k), and the gradient can be expressed as:

[0049]

[0050] Wherein, Z represents a positive integer set, and the gradient ΔR(n) represents the rate of change of the color parameter R. As the dosage increases, ΔR(n) also increases.

[0051] The self-regulating titration method divides the intervals into different dosing strategies according to the size of ΔR(n). The specific dosing strategies are shown in Table 1.

[0052] Table 1

[0053] ΔR(k) <![CDATA[[a 1 ,a 2 )]]> <![CDATA[[a 2 ,a 3 )]]> <![CDATA[[a 3 ,a 4 )]]> <![CDATA[[a 4 ,+∞)]]> Dosing rate <![CDATA[V max ]]> <![CDATA[V normal ]]> <![CDATA[V min ]]> <![CDATA[Microcontinuous dosing V seq >

[0054] Among them, a 1 , a 2 , a 3 and a 4 Respectively represent the boundaries of the interval division, V max Indicates the maximum dosing rate, which is applicable to the initial dosing period. When the color parameter gradient is small, the controller controls the dosing peristaltic pump or other dosing mechanism to V max Dosing rate of dosing t 1 sec; V normal Indicates a moderate dosing rate. When the color parameter gradient is detected in [a 2 , a 3 ) automatically switches to V normal Dosing rate of dosing t 2 sec; V min Indicates the minimum dosing rate, when the color parameter gradient is [a 3 , a 4 ) automatically switches to V min Dosing rate of dosing t 3 seconds; when the color parameter gradient is [a 4 , +∞), and continuously add drugs in trace amounts, and start timing with the internal counter of the controller until the titration endpoint is reached. The timing is t 4 ; The overall self-regulating dosing process is drawn as follows Figure 2 .

[0055] Dividing the dosing speed interval according to the gradient can effectively increase the titration rate.

[0056] It should be noted that the present invention effectively solves many problems in the traditional automatic titration process: 1) A single titration rate is not suitable for an analysis process with a large range, which may cause inaccurate titration results in a small range or too long titration time in a large range. By dividing the dosing speed interval by gradient, the titration rate can be automatically adjusted according to the concentration range of the sample. In the low concentration area, a slower titration rate is used to ensure that the reaction is fully carried out and to avoid excessive titration; in the high concentration area, a faster titration rate is used to shorten the titration time and improve efficiency. This adaptive titration rate adjustment method can significantly improve the accuracy and stability of the titration process, making the titration result more accurate and reliable; 2) Gradient division of the dosing speed interval also helps to reduce human intervention and reduce operating errors. In the traditional titration process, the operator needs to manually adjust the titration rate based on experience, which not only increases the difficulty and complexity of the operation, but also easily introduces human errors. The technology of gradient division of the dosing speed interval can realize automatic adjustment and optimization of the titration rate, reduce human intervention, and improve analysis efficiency and accuracy.

[0057] 2) Reaction hysteresis compensation method based on chemical reaction kinetic equation;

[0058] During the titration process, the hysteresis of chemical reaction is a phenomenon that cannot be ignored. The hysteresis refers to the failure of the reaction rate to immediately keep up with the addition rate of the titrant during the chemical reaction between the titrant and the analyte, resulting in a time delay between the actual reaction progress and the theoretical calculated value. This hysteresis has a series of effects on the accuracy and reliability of the results of the titration analysis with high precision requirements.

[0059] In the present invention, a trace amount of continuous drug addition is performed at the end of the titration, and the reaction hysteresis phenomenon will lead to a larger actual amount of drug addition and a larger measurement result.

[0060] Figure 3 For a titration process, the black curve shows the dosage and color change when the drug is fully stirred and added slowly, and the blue curve shows the dosage and color change when the drug is added quickly. It can be seen that when adding the drug quickly, the chemical reaction lag phenomenon can lead to a large dosage. In order to reduce the impact of reaction lag on the results, the time lag formula is summarized and fitted after a large number of experiments:

[0061]

[0062] Among them, k is the lag time coefficient, and its range needs to be determined through a large number of experiments; v is the cumulative dosage of continuous dosing; c is the cumulative dosing time of continuous dosing.

[0063] 3) Calculate the cumulative dosage;

[0064] Through step 1), the dosing speed of each of the four stages can be determined, and the dosing time corresponding to each of the four stages when the titration endpoint is reached can be determined. Then, each value needs to be substituted into the following formula to obtain the final cumulative dosing amount:

[0065] f=v max t max +v normal t normal +v min t min +v max t max +

[0066] v seq (t seq -d τ (t,v)) (3)

[0067] The dosing process controlled by the above method can ensure higher titration accuracy, and the calculated dosing amount is also more accurate.

[0068] Embodiment 2

[0069] The self-regulating rapid titration control system considering chemical reaction hysteresis of the present invention comprises:

[0070] A division module is used to divide a number of continuous gradient intervals, wherein different gradient intervals correspond to different dosing times and dosing rates;

[0071] The titration module is used to measure the color value of the solution at intervals of predicted time during the titration process of the solution; calculate the current gradient according to the measured color value of the solution, judge the gradient interval to which the current gradient belongs, determine the dosing time and dosing rate according to the judged gradient interval, and titrate the solution according to the determined dosing time and dosing rate.

[0072] As an embodiment of the present invention, the continuous gradient intervals are divided into several continuous gradient intervals, wherein the dosing time and dosing rate of different gradient intervals are divided into the continuous gradient intervals [a 1 , a 2 ), [a 2 , a 3 ), [a 3 , a 4 ) and [a 4 , +∞), where [a 1 , a 2 ) The corresponding dosing time and dosing rate are t 1 and V max ; [a 2 , a 3 ) The corresponding dosing time and dosing rate are t 2and V normal ; [a 3 , a 4 ) The corresponding dosing time and dosing rate are t 3 and V min ; [a 4 , +∞) corresponds to the dosing time and dosing rate t 4 and V seq .

[0073] As an embodiment of the present invention, the gradient ΔR(n) is:

[0074]

[0075] Where n=1, 2, ..., mm∈Z, Z represents a positive integer set, R(n) represents a color value detected for the nth time, and δ is the interval prediction time.

[0076] As an embodiment of the present invention, it also includes:

[0077] Calculate the cumulative dosage f as:

[0078] f=v max t max +v normal t normal +v min t min +v max t max +

[0079] v seq (t seq -d τ (t,v)) (3-3).

[0080] The division of modules in the embodiments of the present application is schematic and is only a logical function division. There may be other division methods in actual implementation. In addition, each functional module in each embodiment of the present application may be integrated into a processor, or may exist physically separately, or two or more modules may be integrated into one module. The above-mentioned integrated modules may be implemented in the form of hardware or in the form of software functional modules.

[0081] The present invention has the following characteristics:

[0082] The instrument has a wider measurement range: Due to the use of a self-adjusting variable speed dosing control method, it can meet application scenarios with a wider range of measurements.

[0083] The titration accuracy is higher in the low range: On the contrary, if a single titration rate is used, the unit dosage in the titration process in the low range is large, which can easily lead to large errors.

[0084] The titration time is shorter in the high range: On the contrary, if a single titration rate is used, the dosing rate will be too slow in the early stage of titration in the high range, which will cause the entire titration process of the instrument to take a long time.

[0085] Considering the chemical reaction hysteresis factor, the titration and calculation accuracy is higher: the rate of the chemical reaction process will change due to external factors such as the concentration of the reactants and temperature. Therefore, if the light detection interval is too small, it is easy to cause the reaction to be unfinished but the light measurement has already begun. The method proposed in the present invention can effectively reduce the phenomenon of large measurement results.

[0086] Embodiment 3

[0087] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the self-regulating rapid titration control method considering the hysteresis of chemical reaction are implemented, for example, including: dividing a plurality of continuous gradient intervals, wherein different gradient intervals correspond to different dosing times and dosing rates; in the process of titrating the solution, measuring the color value of the solution at intervals of predicted time; calculating the current gradient according to the measured color value of the solution, judging the gradient interval to which the current gradient belongs, determining the dosing time and dosing rate according to the judged gradient interval, and titrating the solution according to the determined dosing time and dosing rate. The memory may include a memory, such as a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk memory, etc. The processor, the network interface, and the memory are interconnected through an internal bus, and the internal bus may be an industrial standard architecture bus, a peripheral component interconnection standard bus, an extended industrial standard architecture bus, etc. The bus may be divided into an address bus, a data bus, a control bus, etc. The memory is used to store programs. Specifically, the program may include program codes, and the program codes include computer operation instructions. The memory may include memory and nonvolatile memory and provides instructions and data to the processor.

[0088] Embodiment 4

[0089] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the self-regulating rapid titration control method considering the hysteresis of chemical reaction are implemented, for example, including: dividing a number of continuous gradient intervals, wherein different gradient intervals correspond to different dosing times and dosing rates; in the process of titrating the solution, measuring the color value of the solution at intervals of predicted time; calculating the current gradient according to the measured color value of the solution, judging the gradient interval to which the current gradient belongs, determining the dosing time and dosing rate according to the gradient interval obtained by judgment, and titrating the solution according to the determined dosing time and dosing rate. Specifically, the computer-readable storage medium includes, but is not limited to, for example, volatile memory and / or non-volatile memory. The volatile memory may include random access memory (RAM) and / or cache memory (cache), etc. The non-volatile memory may include read-only memory (ROM), hard disk, flash memory, optical disk, magnetic disk, etc.

[0090] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0091] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0092] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0093] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A self-regulating rapid titration control method taking into account chemical reaction hysteresis, characterized in that: include: Dividing a number of continuous gradient intervals, wherein different gradient intervals correspond to different dosing times and dosing rates; During the titration of the solution, the color value of the solution is measured at intervals of predicted time; the current gradient is calculated based on the measured color value of the solution, and the gradient interval to which the current gradient belongs is determined; the dosing time and the dosing rate are determined based on the determined gradient interval; and the solution is titrated based on the determined dosing time and dosing rate.

2. The self-adjusting rapid titration control method considering chemical reaction hysteresis according to claim 1, characterized in that: The continuous gradient intervals are divided into several continuous gradient intervals, wherein the dosing time and dosing rate of different gradient intervals are divided into [a1, a2), [a2, a3), [a3, a4) and [a4, +∞), wherein the dosing time and dosing rate corresponding to [a1, a2) are t1 and V max ; [a2, a3) corresponding to the dosing time and dosing rate is t2 and V normal ; [a3, a4) corresponding to the dosing time and dosing rate is t3 and V min ; [a4, +∞) corresponds to the dosing time and dosing rate t4 and V seq .

3. The self-regulating rapid titration control method considering chemical reaction hysteresis according to claim 1, characterized in that: The gradient ΔR(n) is: Where n = 1, 2, ..., mm∈Z, Z represents a positive integer set, R(n) represents a color value detected for the nth time, and δ is the interval prediction time.

4. The self-adjusting rapid titration control method considering chemical reaction hysteresis according to claim 2, characterized in that: Also includes: Calculate the cumulative dosage f as: f=v max t max +v normal t normal +v min t min +v max t max +v seq (t seq -d τ (t,v))(3-3)。 5. A self-regulating rapid titration control system taking into account chemical reaction hysteresis, characterized in that: include: A division module is used to divide a number of continuous gradient intervals, wherein different gradient intervals correspond to different dosing times and dosing rates; The titration module is used to measure the color value of the solution at intervals of predicted time during the titration process of the solution; calculate the current gradient according to the measured color value of the solution, judge the gradient interval to which the current gradient belongs, determine the dosing time and dosing rate according to the judged gradient interval, and titrate the solution according to the determined dosing time and dosing rate.

6. The self-regulating rapid titration control system considering chemical reaction hysteresis according to claim 5, characterized in that: The continuous gradient intervals are divided into several continuous gradient intervals, wherein the dosing time and dosing rate of different gradient intervals are divided into [a1, a2), [a2, a3), [a3, a4) and [a4, +∞), wherein the dosing time and dosing rate corresponding to [a1, a2) are t1 and V max ; [a2, a3) corresponding to the dosing time and dosing rate is t2 and V normal ; [a3, a4) corresponding to the dosing time and dosing rate is t3 and V min ; [a4, +∞) corresponds to the dosing time and dosing rate t4 and V seq .

7. The self-adjusting fast titration control system considering chemical reaction hysteresis according to claim 5, characterized in that: The gradient ΔR(n) is: Where n = 1, 2, ..., mm∈Z, Z represents a positive integer set, R(n) represents a color value detected for the nth time, and δ is the interval prediction time.

8. The self-regulating rapid titration control system considering chemical reaction hysteresis according to claim 6, characterized in that: Also includes: Calculate the cumulative dosage f as: f=v max t max +v normal t normal +v min t min +v max t max +v seq (t seq -d τ (t,v))(3-3)。 9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the self-adjusting fast titration control method considering the chemical reaction lag as described in any one of claims 1 to 4 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the self-adjusting fast titration control method considering chemical reaction hysteresis as described in any one of claims 1 to 4 are implemented.

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