CN215274921U

CN215274921U - Blood recovery machine with stable blood flow velocity

Info

Publication number: CN215274921U
Application number: CN202121698370.9U
Authority: CN
Inventors: 马胜利; 黄帆; 许维莹; 宋洁; 侯晓霞
Original assignee: Beijing Jingjing Medical Equipment Co Ltd
Current assignee: Beijing Jingjing Medical Equipment Co Ltd
Priority date: 2021-07-24
Filing date: 2021-07-24
Publication date: 2021-12-24
Anticipated expiration: 2031-07-24

Abstract

The application relates to a blood recovery machine with stable blood flow rate, which relates to the field of medical equipment and comprises a liquid inlet pipe, a centrifugal well, a rolling pump, an anticoagulation system and a controller; the liquid inlet pipe is used for providing a flow channel for waste blood flowing out of the wound; the centrifugal well is connected with the liquid inlet pipe; the rolling pump drives the waste blood flowing through the liquid inlet pipe to flow into the centrifugal well; the anticoagulation system comprises a feeding pipe which is communicated with the liquid inlet pipe and is used for adding anticoagulant and an anticoagulation pump which drives anticoagulant to enter the liquid inlet pipe in a certain proportion; the controller is connected the anticoagulation pump for control the operating condition of anticoagulation pump. The anticoagulant can be added to waste blood through the filling tube in a certain proportion, and waste blood can be avoided condensing on the tube wall when flowing through the liquid inlet tube and the flow speed of waste blood is slowed down, so that waste blood can flow through the liquid inlet tube at a stable flow speed.

Description

Blood recovery machine with stable blood flow velocity

Technical Field

The application relates to the field of medical equipment, in particular to a blood recovery machine with stable blood flow rate.

Background

The blood recovery machine is a medical device which can filter, separate, clean and purify blood collected from a patient operation and then return the blood to the patient, and can recycle waste blood to create good social and economic benefits.

In the related art, in the process that waste blood flowing out of a patient wound flows to a centrifugal well for purification, part of the waste blood can be solidified on a transfusion pipeline, so that the blood flow speed is reduced, and the conveying of the waste blood is influenced. Moreover, if the infusion tube is not cleaned in time, the solidification area is gradually increased, and even the infusion tube is possibly blocked, which is inconvenient for conveying waste blood.

SUMMERY OF THE UTILITY MODEL

In order to stabilize the flow rate of waste blood, the present application provides a blood recovery machine with a stable blood flow rate.

The application provides a stable blood of blood velocity of flow machine adopts following technical scheme:

a blood recovery machine with stable blood flow rate comprises a liquid inlet pipe, a centrifugal well, a roller press pump, an anticoagulation system and a controller;

the liquid inlet pipe is used for providing a flow channel for waste blood flowing out of the wound;

the centrifugal well is connected with the liquid inlet pipe;

the rolling pump drives the waste blood flowing through the liquid inlet pipe to flow into the centrifugal well;

the anticoagulation system comprises a feeding pipe which is communicated with the liquid inlet pipe and is used for adding anticoagulant and an anticoagulation pump which drives anticoagulant to enter the liquid inlet pipe in a certain proportion;

the controller is connected the anticoagulation pump for control the operating condition of anticoagulation pump.

Through adopting above-mentioned technical scheme, the anticoagulant can be with a certain proportion through the filling tube add to useless blood in, can avoid useless blood to condense on the pipe wall and lead to useless blood flow rate to slow down when flowing through the feed liquor pipe for useless blood can flow through from the feed liquor pipe with stable velocity of flow.

Optionally, the position where the feeding pipe is communicated with the liquid inlet pipe is located between the end part, close to the wound, of the liquid inlet pipe and the position acted by the roller press pump.

Optionally, the controller is connected to the anticoagulation pump through a signal isolation unit, and is configured to output an enable signal and a direction signal;

the anticoagulation pump is used for driving the anticoagulation agent to flow according to a specific direction when receiving the enabling signal and the direction signal.

Optionally, the blood transfusion system further comprises an interruption probe, wherein the interruption probe is used for detecting whether the interruption phenomenon occurs in the waste blood during the transportation process and outputting an interruption signal when the interruption phenomenon occurs;

the controller is connected with the current interruption probe and used for receiving the current interruption signal.

Optionally, the blood layer probe is further included, the centrifugal well is connected with a liquid outlet pipe, and the liquid outlet pipe is used for discharging turbid liquid in the waste blood;

the blood layer probe is used for detecting the liquid level of blood in the centrifugal well so as to output a liquid level signal when the liquid level of the blood in the centrifugal well reaches the highest value;

the controller is connected with the blood layer probe and is also used for outputting an inversion signal when receiving the liquid level signal;

the rolling pump is connected with the controller and used for controlling blood in the liquid inlet pipe to flow out of the centrifugal well when receiving the reverse signal.

Optionally, the cleaning device further comprises a cleaning degree probe for detecting the cleanliness of the liquid flowing through the liquid outlet pipe so as to output a cleaning signal when no turbid liquid exists in the liquid flowing through the liquid outlet pipe;

the controller is connected with the cleaning degree probe and is also used for outputting the reversal signal when simultaneously receiving the liquid level signal and the cleaning signal.

Optionally, a leakage detection piece is arranged in the centrifugal well, and the leakage detection piece is used for detecting a leakage situation of the centrifugal well in an operation process so as to output a leakage signal during leakage;

the controller is connected with the leakage detection piece and used for controlling the blood recovery machine to stop working when the leakage detection signal is received.

In summary, the present application includes at least one of the following beneficial technical effects:

the anticoagulant can be added to waste blood through the filling tube in a certain proportion, and waste blood can be avoided condensing on the tube wall when flowing through the liquid inlet tube and the flow speed of waste blood is slowed down, so that waste blood can flow through the liquid inlet tube at a stable flow speed.

Drawings

Fig. 1 is a schematic structural view of a multi-functional blood salvage machine according to an embodiment of the present application.

FIG. 2 is a system schematic of the multi-functional blood salvage machine of embodiments of the present application.

FIG. 3 is a flow chart showing the structure of the multi-functional blood-recovering machine according to the embodiment of the present application.

Fig. 4 is a schematic diagram of a driving circuit of an anticoagulation pump driving pump of the multifunctional blood recovering machine according to the embodiment of the present application.

FIG. 5 is a schematic circuit diagram of the blood layer probe of the multifunctional blood recovery machine according to the embodiment of the present application.

FIG. 6 is a schematic circuit diagram of the connection between the leakage detecting member and the controller of the multi-functional blood recovery machine according to the embodiment of the present application.

Description of reference numerals: 101. a controller; 102. a liquid inlet pipe; 103. a centrifugal well; 104. a roller press pump; 105. a negative pressure pump; 106. a blood reservoir; 107. a blood bag; 108. leading a blood vessel; 109. an air exhaust pipe; 110. a feed tube; 111. an anticoagulation pump; 112. a signal isolation unit; 113. a current breaking probe; 114. a blood layer probe; 115. an oscillation unit; 116. a first amplifying unit; 117. a detection unit; 118. a comparison unit; 119. cleaning a degree probe; 120. a second amplifying unit; 121. detecting a missing part; 122. and a power supply module.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is further described in detail below with reference to fig. 1-6 and the embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

The embodiment of the application discloses machine is retrieved to stable blood of blood velocity of flow for blood is retrieved machine under operating condition, and waste blood can remain stable velocity of flow when the flow through feed liquor pipe.

Referring to fig. 1, 2 and 3, the blood recovering machine with stable blood flow rate includes a controller 101, a liquid inlet pipe 102, a centrifugal well 103, a roller pump 104, a negative pressure pump 105, and a frame body hung with a blood reservoir 106 and a blood bag 107.

Referring to fig. 3, a blood lead tube 108 is connected to the blood reservoir 106, and the negative pressure pump 105 is connected to the blood reservoir 106 via an air suction tube 109, so that when the negative pressure pump 105 starts operating, the negative pressure pump 105 can draw air from the blood reservoir 106 to place the interior of the blood reservoir 106 in a negative pressure state. The blood reservoir 106 under negative pressure can draw waste blood from the wound of the patient into the blood reservoir 106 through the blood-drawing tube 108 for washing and purifying the waste blood.

The liquid inlet pipe 102 is connected to the blood reservoir 106 at one end and to the centrifuge well 103 at the other end. After the waste blood in the blood container 106 is pumped to the centrifugal well 103 by the roller press pump 104, the turbid liquid in the waste blood is discharged from the liquid outlet pipe connected to the centrifugal well 103 by the centrifugal action of the centrifugal well 103, and the remaining blood in the centrifugal well 103 can be pumped to the blood bag 107 by the roller press pump 104.

It is worth noting that the roller pump 104 is preferably a peristaltic pump in the present application, and the roller pump 104 allows the waste blood in the blood reservoir 106 to flow into the centrifugal well 103 by rotating in two different directions, and simultaneously allows the blood in the centrifugal well 103 to flow into the blood bag 107 for storage.

The liquid inlet pipe 102 is preferably a four-way pipe in the present application, and has two ends connected to the blood reservoir 106 and the centrifugal well 103, respectively, and a portion connecting the blood reservoir 106 and the centrifugal well 103 passes through the roller press pump 104, and the other two branches are located at a portion between the blood reservoir 106 and the pressing position of the roller press pump 104. One branch is connected to the device containing clean saline and the other branch is connected to the blood bag 107 so that the waste blood is mixed with the washing saline during the flow into the centrifugal well 103 to separate the turbid liquid in the waste blood by the centrifugal well 103.

Besides, an anticoagulation system is arranged on the machine body, and comprises a feeding pipe 110 which is communicated with the liquid inlet pipe 102 and is used for adding anticoagulant and an anticoagulation pump 111 which drives anticoagulant to enter the liquid inlet pipe 102 in a certain proportion, so that the mixed liquid of the waste blood and the cleaning saline flowing through the liquid inlet pipe 102 can not be condensed on the pipe wall to cause the blockage of the liquid inlet pipe 102. In the present embodiment, the position of the feeding tube 110 connected to the fluid inlet tube 102 is preferably set between the end of the fluid inlet tube 102 near the wound and the position acted on by the roller pump 104, so as to control the ratio of the waste blood, the washing saline and the anticoagulant within a proper range.

It will be appreciated that the inlet tube 102 is provided with a tubing clamp for controlling the communication of the manifold on the manifold connecting the blood bag 107, the blood reservoir 106 and the device containing the wash saline. By controlling the positions of the plurality of pipe clamps, the waste blood treatment process and the blood conveying process can be independently carried out.

In order to realize the functions of the blood recovery machine in the embodiment of the present application, a corresponding blood recovery machine system is further provided based on the structure of the blood recovery machine in the embodiment of the present application. The system parts of the blood salvage machine are described in detail below:

referring to fig. 2, for an anticoagulation system, the anticoagulation pump 111 is controlled by the controller 101 connected to the anticoagulation pump 111 to drive the anticoagulation agent to flow in a specific direction. Specifically, the controller 101 has an enable output for driving the anticoagulation pump 111 to work and a direction output, wherein the enable output is capable of outputting an enable signal, and the direction output is capable of outputting a direction end.

Referring to fig. 2 and 3, it can be appreciated that the anticoagulation pump 111 in the present application is preferably a peristaltic pump that is rotatable in two different directions so that the liquid being transferred can flow in two different directions. In actual operation, only anticoagulant needs to be added into the liquid inlet pipe 102 through the feeding pipe 110, that is, the anticoagulant pump 111 only needs to work continuously around one direction, and it can be understood that the level output by the direction output end of the controller 101 is set to be a constant value.

Referring to fig. 2 and 4, the anticoagulation pump 111 is configured to drive the anticoagulation agent to flow in a specific direction when receiving the enable signal and the direction signal, and is internally provided with an anticoagulation pump driving chip and a corresponding peripheral circuit. Specifically, the anti-coagulation pump driving chip is connected with the peripheral circuit to generate a direction input end and an enabling input end, the direction input end is connected with the direction output end, and the enabling input end is connected with the enabling output end. When the anticoagulation pump driving chip receives the enable signal and the direction signal at the same time, the anticoagulation pump 111 can start to operate and operate according to the direction set by the direction signal. Conversely, when the anticoagulation pump driving chip does not receive the enable signal, the anticoagulation pump 111 does not work.

In addition, the controller 101 is connected to the peripheral circuit of the anticoagulation pump driving chip through the signal isolation unit 112 to protect the whole system of the blood recovering machine. Since the signal isolation unit 112 is a conventional means in circuit design, and belongs to a mature technology, the signal isolation unit 112 will not be described in detail here.

Referring to fig. 1 to 3, although anticoagulant is added to the waste blood flowing through the inlet tube 102 to prevent the waste blood from coagulating on the walls of the tubes, a flow interruption phenomenon may occur during the flow of the waste blood from the inlet tube 102 to the centrifugal well 103 due to, for example, squeezing of the inlet tube 102. Therefore, the inlet tube 102 is provided with a blocking probe 113 for detecting whether the waste blood is blocked during the transportation.

Referring to fig. 2, in detail, the output terminal of the current interrupt probe 113 outputs a current interrupt signal when it detects that a current interrupt occurs in the liquid inlet pipe 102, and otherwise does not output the current interrupt signal. The controller 101 is connected to the output of the cutoff probe 113 for receiving a cutoff signal to monitor the flow of waste blood into the centrifuge well 103 throughout the process so that the waste blood can be maintained at a steady flow rate into the centrifuge well 103.

It should be noted that since the power supply of the current interrupt probe 113 and the power supply of the controller 101 have different levels, the signal receiving terminal of the controller 101 cannot be directly connected to the output terminal of the current interrupt probe 113, and the level needs to be converted by the level converting unit so that the power supply of the controller 101 matches the level of the power supply of the current interrupt probe 113.

Referring to fig. 3, in the blood collection machine, the most important step is to centrifuge the mixed solution of waste blood and washing saline through the centrifugal well 103 to discharge turbid solution to obtain clean blood.

Referring to fig. 1 and 3, in particular, when the centrifugal well 103 is rotated at a high speed, the mixture of waste blood and wash saline in the centrifugal well 103 can be separated by centrifugation, i.e., clean blood is located below the inside of the centrifugal well 103 and turbid liquid is located above the clean blood. Accordingly, the outlet pipe is preferably located above the centrifuge well 103 in the embodiment of the present application to facilitate the discharge of the turbid liquid.

Referring to fig. 1-3, in order to detect the blood volume of the clean blood in the centrifugal well 103 in real time, a blood layer probe 114 for detecting the liquid level height of the clean blood in the centrifugal well 103 is disposed on the centrifugal well 103, and when the blood layer probe 114 detects that the liquid level of the blood in the centrifugal well 103 reaches a maximum value, a liquid level signal is output, so as to adjust the rotation direction of the roller pump 104 after the clean blood in the centrifugal well 103 is saturated, and then the clean blood is conveyed to the blood bag 107 through the liquid inlet tube 102.

Referring to fig. 2 and 5, it is worth explaining that the circuit part for realizing the above-described process in the whole system of the blood collection machine includes an oscillation unit 115, a first amplification unit 116, a detection unit 117, and a comparison unit 118.

Wherein, the oscillation unit 115 is connected to the signal receiving end of the blood layer probe 114 to provide the blood layer probe 114 with a square wave signal. In the present embodiment, the oscillation unit 115 is preferably a multivibrator chip of the type HCCC4047 BF.

Referring to fig. 2, 3 and 5, the blood layer probe 114 obtains the level of clean blood in the centrifugal well 103 in real time at the frequency of the square wave signal provided by the oscillation unit 115, and outputs a height signal from the signal output terminal.

Referring to fig. 2 and 5, the first amplification unit 116 is connected to the signal output terminal of the blood layer probe 114, and is used for amplifying the signal strength of the height signal, and mainly comprises an amplifier and a peripheral circuit. The detection unit 117 is connected to the first amplification unit 116, and is configured to remove noise in the amplified height signal. Since the first amplifying unit 116 and the detecting unit 117 are conventional in circuit design and are well-known in the art, they will not be described in detail here.

The comparison unit 118 is composed of a comparator and a peripheral circuit. Specifically, the non-inverting input terminal of the comparator is used for accessing a preset value, and the size of the preset value can be adjusted by connecting the sliding rheostat. Of course, the non-inverting input terminal may be connected to the controller 101, and a constant value may be preset as the preset value. The inverting input of the comparator is connected to the output of the detection unit 117 to receive the height signal detected by the blood layer probe 114. When the liquid level height value reflected by the height signal exceeds a preset value, the output end of the comparator outputs a liquid level signal. And conversely, when the liquid level height value reflected by the height signal is lower than the preset value, the output end does not output the liquid level signal.

It is understood that a test terminal is also connected between the output of the first amplifying unit 116 and the output of the comparing unit 118, so as to adjust the amplification factor of the first amplifying unit 116 when the circuit is connected.

Referring to fig. 2 and 5, the controller 101 is connected to the output of the comparator for receiving the liquid level signal to output the inverted signal from the signal output. It should be noted that since the power supply of the comparing unit 118 and the power supply of the controller 101 have different levels, the signal receiving terminal of the controller 101 cannot be directly connected to the output terminal of the comparator, and the level needs to be converted by the level converting unit so that the power supply of the controller 101 and the power supply of the comparing unit 118 match.

Referring to fig. 1-3, since the roller pumps 104 are also peristaltic pumps, the controller 101 may change the rotational direction of the roller pumps 104 by adjusting the level of the corresponding direction signal.

Referring to fig. 2 to 4, in particular, the rolling pump 104 is used for driving the liquid in the liquid inlet pipe 102 to flow in a specific direction when receiving an enable signal and a direction signal, and a rolling pump driving chip and a corresponding peripheral circuit are arranged inside the rolling pump 104. Specifically, the roller pump driving chip is connected with a peripheral circuit to generate a direction input end and an enable input end, the direction input end is connected with the direction output end, and the enable input end is connected with the enable output end. When the roller pump driver chip receives the enable signal and the direction signal at the same time, the roller pump 104 can start to operate and operate according to the direction set by the direction signal. Conversely, when the roller pump driver chip does not receive the enable signal, the roller pump 104 is not operated.

Referring to fig. 2 and 4, in order to protect the rolling pump 104 and the whole system of the blood recovery machine, a rolling pump 104 fault detection function is provided inside the rolling pump driving chip, that is, whether the rolling pump 104 has a fault during the working process can be detected. The controller 101 is also connected with each port of the peripheral circuit of the roller pump driving chip through a signal isolation unit 112 to protect the whole system of the blood recovery machine.

Referring to fig. 1-3, a washing degree probe 119 is disposed outside the outlet pipe, considering that a small amount of turbid liquid may remain in the centrifugal well 103 when the centrifugal well 103 discharges the turbid liquid. The cleanliness probe 119 is used to detect the cleanliness of the liquid flowing through the effluent channel to output a cleaning signal when there is no turbidity in the liquid flowing through the effluent channel. It should be noted that the output end of the cleaning degree probe 119 is connected to a second amplifying unit 120 for amplifying the cleaning signal. Meanwhile, the output terminal of the second amplifying unit 120 is connected to the input terminal of the controller 101 through the signal isolating unit 112.

Referring to fig. 2 and 3, it can be understood that the blood bag 107 is supplied with clean blood when the turbid liquid in the centrifugal well 103 is completely removed and the clean blood is saturated, and therefore, the controller 101 controls the roller pump 104 to change the rotation direction to make the clean blood flow into the blood bag 107 under the driving of the roller pump 104 when receiving the liquid level signal and the cleaning signal at the same time.

With reference to fig. 2, 3 and 6, in order to prevent leakage of the centrifuge well 103 in the operating state, which could affect the entire system of the blood recovery machine, a leak detector 121 is also provided in the centrifuge well 103 for this purpose. The leak detector 121 is preferably an interdigital electrode, i.e., two electrodes having a plurality of contacts are arranged facing each other and staggered. When liquid leaks from the centrifugal well 103 and is sprinkled on the interdigital electrodes, the two electrodes can be conducted, so that the liquid leakage condition in the centrifugal well 103 can be detected.

When the leakage detecting part 121 detects the leakage condition of the centrifugal well 103 in the operation process, the leakage detecting part 121 outputs a leakage signal. The controller 101 is connected to the output end of the leakage detecting element 121, and is used for controlling the blood recovering machine to stop working when receiving a leakage signal so as to protect the whole system of the blood recovering machine.

Based on the control function of the controller 101, the controller 101 in the embodiment of the application is a single chip microcomputer, and the model number of the single chip microcomputer is STM32F407VET 6.

Furthermore, a power module 122 is provided in the whole system of the blood recovering machine to supply power to the above-mentioned chips, components, and the like.

The implementation principle of the blood recovery machine with stable blood flow velocity in the embodiment of the application is as follows: by arranging the feeding pipe 110 between the end part of the liquid inlet pipe 102 close to the wound and the position acted by the roller pump 104, anticoagulant is added into the waste blood flowing process to the centrifugal well 103, so that the coagulation effect of coagulation factors in the waste blood can be inhibited, the effect of preventing blood from coagulating is achieved, and the waste blood can flow through the liquid inlet pipe 102 at a stable flow rate.

The foregoing is a preferred embodiment of the present application and is not intended to limit the scope of the application in any way, and any features disclosed in this specification (including the abstract and drawings) may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. That is, unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features.

Claims

1. The utility model provides a blood machine of retrieving of stable blood velocity of flow which characterized in that: comprises a liquid inlet pipe (102), a centrifugal well (103), a rolling pump (104), an anticoagulation system and a controller (101);

the liquid inlet pipe (102) is used for providing a flow channel for waste blood flowing out of the wound;

the centrifugal well (103) is connected with the liquid inlet pipe (102);

the rolling pump (104) drives the waste blood flowing through the liquid inlet pipe (102) to flow into the centrifugal well (103);

the anticoagulation system comprises a feeding pipe (110) which is communicated with the liquid inlet pipe (102) and is used for adding anticoagulant, and an anticoagulation pump (111) which drives anticoagulant to enter the liquid inlet pipe (102) in a certain proportion;

the controller (101) is connected the anticoagulation pump (111) for controlling the operating condition of the anticoagulation pump (111).

2. A blood salvage machine according to claim 1, wherein: the position of the feed pipe (110) communicated with the liquid inlet pipe (102) is positioned between the end part of the liquid inlet pipe (102) close to the wound and the position acted by the roller press pump (104).

3. A blood salvage machine according to claim 1, wherein: the controller (101) is connected with the anticoagulation pump (111) through a signal isolation unit (112) and is used for outputting an enable signal and a direction signal;

the anticoagulation pump (111) is used for driving the anticoagulation agent to flow according to a specific direction when receiving the enabling signal and the direction signal.

4. A blood salvage machine according to claim 1, wherein: the blood-feeding device also comprises an interruption probe (113), wherein the interruption probe (113) is used for detecting whether the interruption phenomenon occurs to the waste blood during the delivery process and outputting an interruption signal when the interruption phenomenon occurs;

the controller (101) is connected with the current interruption probe (113) and is used for receiving the current interruption signal.

5. A blood salvage machine according to claim 1, wherein: the device also comprises a blood layer probe (114), the centrifugal well (103) is connected with a liquid outlet pipe, and the liquid outlet pipe is used for discharging turbid liquid in the waste blood;

the blood layer probe (114) is used for detecting the liquid level of the blood in the centrifugal well (103) so as to output a liquid level signal when the liquid level of the blood in the centrifugal well (103) reaches a highest value;

the controller (101) is connected with the blood layer probe (114) and is further used for outputting an inversion signal when receiving the liquid level signal;

the rolling pump (104) is connected with the controller (101) and is used for controlling the blood in the liquid inlet pipe (102) to flow out of the centrifugal well (103) when the reverse signal is received.

6. A blood salvage machine according to claim 5, characterized in that: the liquid level sensor also comprises a cleaning degree probe (119) which is used for detecting the cleanliness of the liquid flowing through the liquid outlet pipe so as to output a cleaning signal when turbid liquid does not exist in the liquid flowing through the liquid outlet pipe;

the controller (101) is connected with the cleaning degree probe (119) and is further used for outputting the reverse signal when receiving the liquid level signal and the cleaning signal at the same time.

7. A blood salvage machine according to claim 5 or 6, characterized in that: a leakage detection piece (121) is arranged in the centrifugal well (103), and the leakage detection piece (121) is used for detecting the leakage condition of the centrifugal well (103) in the operation process so as to output a leakage signal in the leakage process;

the controller (101) is connected with the leakage detection piece (121) and is used for controlling the blood recovery machine to stop working when receiving the leakage signal.