EP2743919A2 - Device for applying ultrasound to liquid media through a membrane and ultrasound system - Google Patents

Abstract

The device (1) has an ultrasound generator (5) for generating ultrasound. A sound conducting element (2) conducts the generated ultrasound. The sound conducting element comprises a contact surface (15) for uncoupling the ultrasound at a flexible material i.e. membrane. The sound conducting element comprises a channel (18) with an opening (20) for applying low pressure to the channel, and another opening (17) for applying the low pressure to the flexible material. Piezoelectric elements (21, 22) are connected with a power supply for vibration stimulation of the piezoelectric elements. The sound conducting element is designed as a rotation symmetrical rod. An independent claim is also included for an ultrasound system.

Description

The invention relates to a device for applying liquid media with ultrasound through a membrane, wherein the device comprises an ultrasound generator for generating ultrasound and a sound conducting element for guiding the ultrasound generated by the ultrasound generator, and the sound conducting a contact surface for coupling the ultrasound to a flexible medium or flexible material (the terms "flexible medium" and "flexible material are used as synonyms in the present application), in particular a membrane.

In previously available devices, it is problematic to produce an efficient sound transmission between the device and a flexible material, such as a membrane. About such a flexible material can also be a coupling into a liquid. To improve the transition of ultrasound from the device to a flexible material It is known to press the device against the flexible material. Here, the flexible material is mechanically stressed, which can lead to damage of the flexible material.

The object of the invention is to propose a device which enables the most efficient possible ultrasonic coupling to a flexible material, wherein a mechanical stress of the flexible material is kept as low as possible.

This object is achieved by a device according to claim 1 and an ultrasound system according to claim 15. Further possible embodiments are explained in the dependent claims.

Because the sound conducting element comprises a channel with a first opening for connecting a pump to the channel and a second opening for applying a negative pressure to the flexible material, for example within the contact surface, a flexible material can be coupled into the ultrasound be sucked by means of negative pressure to the contact surface. This allows a very even distribution of a contact pressure over the contact surface. A mechanical stress of the flexible material is thus reduced. In addition, a negative pressure can be adjusted particularly well reproducible and precise.

The ultrasound generator may, for example, comprise at least one piezoelectric element. A particularly precise control of the intensity of the irradiated ultrasound is possible if the ultrasound generator comprises a plurality of piezoelectric elements, wherein at least a first piezoelectric element of the generation of ultrasound and at least one second piezoelectric element is used for the detection of ultrasound, and is suitably connected thereto. For example, the at least one first piezoelectric element may be connected to a voltage supply for the vibration excitation of the first piezoelectric element. The second piezoelectric element may, for example, be connected to a measuring device for measuring the ultrasound passing through the second piezoelectric element. The measuring device may, for example, via the voltage generated by the at least one second piezoelectric element, the amplitude and / or power of the ultrasound passing through the second piezoelectric element. The second piezoelectric element may, for example, be arranged between the first piezoelectric element and the contact surface, in particular between the first piezoelectric element and the sound conducting element. Instead, however, the first piezoelectric element may also be arranged between the second piezoelectric element and the sound conducting element.

In order to ensure a time constant introduction of the negative pressure can be arranged in the region of the contact surface, the contact surface circumferential sealing element. When the contact surface is now brought into contact with a flexible material, the sealing element, the contact surface and the flexible material form a pressure space in which the flexible material is sucked against the contact surface with a uniform pressure. Alternatively or in addition to a sealing element, the contact surface may be concave. However, it is also a planar shape (especially when a sealing element is used) of the contact surface possible. The outer region of the contact surface then forms a sealing edge, which has the same effect as a sealing element. By using a seal and / or concave contact surface, the escape of the negative pressure is largely avoided. As a result, a negative pressure maintained by a pump with low flow rate, which allows the use of pulsation-free pumps.

The sound conducting element, which may be arranged so that the ultrasound is passed through the sound conducting element, may have at least one tapered region. A region is regarded as being tapered if, in this region, the cross-sectional area of the sound-conducting element in a plane orthogonal to the direction of sound propagation is smaller than the cross-sectional area outside this region. In particular, the cross-sectional area in the tapered region can be smaller than the contact surface. By means of such a tapered region, the amplitude of the ultrasound which reaches the contact surface can be influenced. In particular, the ultrasound can be concentrated to a relatively small cross section by the tapered region. As a result, an increase in the amplitude of the ultrasound at the contact surface is 3 to 5 times the amplitude present directly at the ultrasound generator possible. In order to minimize the wear of the second part of the sound-conducting element and of the flexible medium, the maximum amplitude at the contact surface can be, for example, less than 30 micrometers. In particular, the maximum amplitude may be between 10 and 20 microns.

The sound-conducting element can be designed, for example, rotationally symmetrical and, in particular, as a rotationally symmetrical rod. However, it can also be designed differently from a rotationally symmetrical shape. For example, the sound-conducting element can be shaped as a rod with a triangular or quadrangular cross-section.

The sound conducting element may have a first part connected to the ultrasound generator and a second part having the contact surface. The two parts are then connected to each other, wherein the compound may be formed in particular detachable. For example, the connection may be formed as a screw connection. The two-part design of the Schallleitelements allows, with little effort to replace the bearing surface having part. This is advantageous because the contact surface is most affected by wear.

The tapered region can be arranged in particular in the second part having the contact surface. In particular, there may be a plurality of second parts for the device, which differ with regard to the cross section in the tapered region. Accordingly, the intensity of the ultrasound that comes to the contact surface can be changed by replacing an easily replaceable part, which is already occasionally replaced due to wear anyway.

In addition, a taper portion in which the cross section decreases in the direction of the abutment surface may be arranged in the first part. Through this taper section, an ultrasound generator having a large cross-sectional area and a small amplitude can be used, wherein the ultrasound is concentrated by the taper section to a smaller cross-sectional area.

Has both a rejuvenation section and tapered area, wear both contribute to the amplification of the amplitude at the contact surface.

In particular, the channel can at least partially pass through both the first and the second part of the sound-conducting element. The second part, for example, can also be completely traversed by the channel. The arranged in the contact surface second opening is then part of the second part, while serving to connect a pump first opening is part of the first part. Characterized in that the serving to connect the pump opening is part of the first part, it is not necessary in case of (for example, wear-related) replacement of the second part to release a connection between the pump and the device.

A diameter of the channel can change over its length. In particular, the diameter of the channel may change within the second part and / or in the region of the connection between the first and the second part. By replacing the second part with a similarly shaped second part but differing in the diameter of the channel in the region of the abutment surface (i.e., the diameter of the second opening), a suction force applied to the abutment surface can be changed.

In addition, the device may comprise a termination element which is arranged on the side remote from the sound conducting element side of the ultrasound generator.

The first part, the second part and / or the closing element may be formed of the same or of different materials. In particular, a solid material that can withstand high vibration / strain stresses comes into question as materials. The material or materials should be low in attenuation. For example, suitable metals, alloys, plastics or ceramics may be used as the material.

The sound-conducting element can also be formed in one piece. Even with a one-piece design, the above-mentioned materials for the Schalleitelement can be used.

The ultrasound generator can be set up to generate ultrasound at a frequency between 20 kHz and 100 kHz (in particular between 30 kHz and 40 kHz). The length of the device may be in particular half of the ultrasonic wavelength, so that a standing wave can form in the ultrasonic transducer. The device can thus be designed as a λ / 2 converter.

A connection between the first part and the second part of the sound-conducting element can in particular be between one sixteenth and three sixteenths of the wavelength λ from the connection surface. The term "wavelength λ" is to be understood here as meaning the wavelength of the ultrasound in the material of the sound-conducting element (for example titanium). This arrangement of the connection is advantageous, since in this region of the device, the oscillation amplitude is still low, and the tension against the tension in the middle of the device has already dropped significantly. The connection between the first and the second part of the sound conducting element is thus not overstressed, i. the mechanical stress of the connection is in the tolerable range.

In principle, it is also possible to design the second part as a thin plate-shaped attachment. The connection is then only slightly removed from the contact surface. However, this results in a significantly greater oscillation amplitude in the region of the connection. As a result, a gap between the first and second part arise, and this is not desirable. In addition, the design freedom would be severely limited in terms of the channel and the contact surface.

The first opening of the channel, which may be arranged in the first part as already mentioned, may for example be approximately one quarter of the wavelength (in particular between 0.2λ and 0.3λ) away from the connection surface, ie the first opening may be in particular in the middle Be arranged 20% of the length of the ultrasonic transducer. By this is meant that the opening of the channel from a zero vibration level of the device (ie the plane in which the amplitude of the oscillation is zero) can be longitudinally less than ± 10% of the length of the device. In this area, there is only a small longitudinal amplitude. Thus, a connection becomes too a small load on a pump, which significantly reduces the risk of leaks in the connection between the duct and the pump.

In particular, a power of the ultrasound generated by the ultrasound generator may be between 5W and 20W. The amplitude of the ultrasound may be, for example, between 10 and 30 μm at the contact surface. An amplitude in this range is sufficient to induce cavitation in the case of liquids to be treated with a low-attenuation membrane, the amplitude still being sufficiently low in order to minimize wear in the region of the contact surface.

In particular, the first opening may be arranged in a side face that is substantially orthogonal to a radiation direction of the ultrasound generator. A side surface is considered substantially orthogonal if its surface normal has an angle between 60 ° and 120 ° to the emission direction. In particular, the angle can be between 80 ° and 100 °.

In addition to a device, the invention also relates to an ultrasound system having a device as described above. The ultrasound system further includes a pump configured to generate a negative pressure and connected to the channel via the first opening. The ultrasound system may further comprise a membrane applied to the contact surface as a flexible material. Such a membrane can be used to surround, for example, liquids to be treated with ultrasound.

Fign. 1a und 1b

Schnitt durch und Aufsicht auf eine Ausführungsform einer Vorrichtung zur Beaufschlagung flüssiger Medien mit Ultraschall durch eine Membran,

Fig. 1c

Detailansicht einer Variante der Vorrichtung aus den Fign. 1a und 1b,

Fign. 2a bis 2d

Schnittansicht, Aufsicht sowie zwei Detailansichten eines ersten Teils des Schallleitelements der Vorrichtung aus Fig. 1,

Fign. 3a und 3b

Schnittansicht sowie Aufsicht eines zweiten Teils des Schallleitelements der Vorrichtung auf Fig. 1,

Fig. 4

ein Querschnitt durch einen weiteren Teil der Vorrichtung aus Fig. 1,

Fig. 5

ein prinzipieller Verlauf der Spannung und der Schwingungsamplitude über die Vorrichtung aus Fig. 1,

Fign. 6a und 6b

Schnittansicht sowie Aufsicht einer weiteren Ausführungsform einer Vorrichtung zur Beaufschlagung flüssiger Medien mit Ultraschall durch eine Membran und

Fig. 7a bis 7d

Schnittansichten durch sowie Aufsichten auf alternativer Ausgestaltungen einer Ansaugfläche für die Vorrichtung aus Figur 1.

In addition, the ultrasound system may include a power supply configured to supply the ultrasound generator - which may include a piezoelectric element as mentioned above - with a voltage for vibrational excitation of the ultrasound generator. Furthermore, the ultrasound system can have a measuring device for determining the amplitude and / or intensity of the ultrasound generated. The measuring device can determine the amplitude and / or intensity in particular via the voltage of the second piezoelectric element. Embodiments of the invention will be explained in more detail with reference to FIGS. Show it:

FIGS. 1a and 1b

Section through and plan view of an embodiment of a device for applying liquid media with ultrasound through a membrane,

Fig. 1c

Detail view of a variant of the device from the FIGS. 1a and 1b .

FIGS. 2a to 2d

Sectional view, top view and two detailed views of a first part of the Schallleitelements of the device Fig. 1 .

FIGS. 3a and 3b

Sectional view and supervision of a second part of the Schallleitelements the device Fig. 1 .

Fig. 4

a cross section through another part of the device Fig. 1 .

Fig. 5

a fundamental course of the voltage and the oscillation amplitude over the device Fig. 1 .

FIGS. 6a and 6b

Sectional view and top view of another embodiment of a device for applying liquid media with ultrasound through a membrane and

Fig. 7a to 7d

Sectional views through and on views of alternative embodiments of a suction for the device FIG. 1 ,

In the FIGS. 1a and 1b is a device 1 in cross section and in supervision shown. The device 1 has a sound-conducting element 2, consisting of a first part 3 and a second part 4 (also referred to as ultrasonic suction foot). Furthermore, the device comprises an ultrasound generator 5 and a rear terminating element 6.

The ultrasonic generator 5, which is arranged in this embodiment for generating ultrasound at a frequency of 30 kHz, is clamped between the first part 3 of the Schallleitelements 2 and the rear end element 6. For this purpose, the closing element 6 is equipped with a receptacle 7 for a screw. The first part of the Schallleitelements 2 in turn has a threaded bore 8, in which a screw 9, the head 10 is arranged in the closing element 6, is screwed. The first part 2 furthermore has a screw-in opening 11 which is directed away from the ultrasound generator 5 and into which the second part 4 of the sound-conducting element 2 is screwed. For this purpose, the second part 4 of the sound-conducting element 2 has a thread 12. To facilitate screwing the second part 4 of the Schallleitelements 2 in the first part 3, both the first and the second part 4 of the Schallleitelements on key surfaces 13 and 14 on which by means of a conventional wrench, a force can be introduced. The second part 4 of the Schallleitelements 2 also has a contact surface 15 which is equipped with a circumferential O-ring 16 and is used for coupling the ultrasound in a flexible medium. In the middle of the contact surface 15, an opening 17 is arranged, which communicates with a channel 18 in connection. The channel 18 passes completely through the second part 4 of the sound-conducting element and at least partially through the first part 3. The end facing away from the opening 17 of the channel 18 is disposed within the first part 3 of the Schallleitelements. There is the channel 18 with a connecting piece 19 which has an opening 20, in conjunction. About this connector 19, a conventional hose can be pushed and fastened for example with a hose clamp. Via the connecting piece 19, the channel 18 can thus be connected to a pump (not shown) via which a negative pressure for sucking the flexible medium against the contact surface 15 can be applied. The diameter of the channel 18 changes within the second part 4. The geometry of the channel in the second part 4 thus influences the suction force on the contact surface. As a pump, in particular a pulsation-free pump can be used become.

The already mentioned ultrasonic generator 5 comprises a plurality of piezoelectric elements 21 to 24. Two of the piezoelectric elements 21 and 22 are connected to a voltage source, not shown, and arranged to generate the ultrasound. The two piezo elements 23 and 24, however, have no power supply but a signal tap, which is in communication with a measuring device, also not shown. This measuring device can determine the amplitude and / or intensity of the ultrasound based on a voltage generated by the piezo elements 23 and 24 as a function of the present ultrasound amplitude. As in the supervision Fig. 1b can be seen, the device 1 also has a flange 25 to which it can be attached.

The device 1 has a length, i. a total extent in the sound propagation direction x, which corresponds to half the wavelength of the ultrasound generated. The device can thus be referred to as a λ / 2 converter. In the present embodiment, the ultrasonic generating apparatus 1 is set at a frequency of 30 kHz. The sound conducting 2 is made of titanium and the end element 6 made of aluminum. The length of the device is thus a little over 17 cm. The sound conducting 2 may be formed as shown in two parts or in one piece. The first part 3, the second part 4, the entire sound-conducting element 2 and / or the end element 6 can also be formed of another metal of an alloy, a plastic or a ceramic instead of titanium. The sound conducting element 2 may have a rotationally symmetrical cross section. However, a cross-section of the sound-conducting element 2 can also deviate from a rotationally symmetrical shape. For example, a triangular or quadrangular cross-section of the sound-conducting element 2 is possible.

In Fig. 1c the suction surface 15 'as a detail of an alternative variant of a device 1 is shown. In the illustrated detail, the contact surface 15 'is curved. The curved, concave-shaped design of the contact surface 15 'no seal is required because the outer edge 26 of the contact surface 15' serves as a sealing edge. Alternatively, the contact surface may also be convex, ie curved in the opposite direction. The The abutment surface can then be pressed against a flexible material (in particular a membrane) for reliable contact and be connected to the flexible material via the opening 17 by means of negative pressure so that the flexible material follows the movement of the abutment surface.

In the FIGS. 2a to 2d is the first part 3 of the Schallleitelements 2 of the device 1 from the FIGS. 1a and 1b shown in section and in supervision. In the sectional view 2a, the two threaded holes 8 and 11 for connecting with the screws 10 and the second part 4 can be seen particularly well.

In addition, it can be seen that the first part has a tapering area 32 in which the cross section (ie the sectional area orthogonal to the direction x FIG. 1 ) From the ultrasonic generator 5 to the contact surface decreases, and a coupling region 33 in which the threaded bore 11 is arranged and thus serves the coupling to the second part 4. The tapering region 32 serves to amplify the amplitude of the ultrasound, the gain being achieved by concentrating the ultrasound in the reduced cross-sectional area.

The ultrasonic generator 5 facing threaded hole 8 is in the detailed view Fig. 2b shown in more detail, while the second part 4 of the Schallleitelements 2 facing threaded bore 11 in the detailed view Fig. 2c is more accurate. In the supervision off Fig. 2b In particular, the flange 25, which can be used to attach the device 1, can be seen.

In the FIGS. 3a and 3b the second part 4 of the sound-conducting element is shown in detail. In the area of the abutment surface 15, the second part of the sound-conducting element has a groove 27 running around the abutment surface 15, which groove is used for fastening the O-ring 16 (cf. Fig. 1a ) serves. At a small distance from the contact surface 15, the part 4 of the sound-conducting element has a tapered region 28, via which the amplitude of the ultrasound, which arrives at the contact surface 15, continues. Together with the tapering region 32 of the first part 3, this results in an amplification of the amplitude at the contact surface 15 with respect to the amplitude at the ultrasonic generator 5 by a factor of 3 to 5. Der second part 4 of the Schallleitelements 2 is very easy to replace, to keep a breakdown, if maintenance is required due to wear of the contact surface 15 as short as possible. The second part 4 can also be exchanged in order to change an intensity of the ultrasound reaching the contact surface 15. For this purpose, a built-in second part 4 of the sound-conducting element 2 can be exchanged for an alternative of the second part 4, which differs in terms of the cross-section in the region of the tapered region 28.

In Fig. 4 the end element 6 is shown in section. As can be seen, the end element 6, the receptacle 7 for the screw head and a through hole for the shank of the screw 9.

In Fig. 5 is the principal course 29 of the tensile stress and the principal course 30 of the oscillation amplitude over the length of the transducer 1 is applied. The position of the contact surface 15 is marked on the X-axis. As can be seen from the course 30, the amplitude of the ultrasonic vibration in the region of the ends of the device 1 is maximum. For example, it can be between 20 and 30 microns. The tension is the lowest at the ends. In contrast, in the region of the vibrational zero level of the device 1, the tensile stress is significantly greater, but the amplitude is very small. Due to the fact that the threaded bores 8 and 11 are arranged close, but not directly, in the oscillation zero level of the device 1, the amplitude of the oscillation in the region of the threaded bore is still low, the tensile stress having already dropped significantly in relation to a tensile stress in the center of the device 1 , The terminal 19 is arranged in the longitudinal direction (ie x-direction) of the transducer in the vibrational level, since there the amplitude is minimal.

It should be noted that the illustrated courses 29 and 30 are only schematic representations. The precise courses, which are influenced by the shape of the device 1 and in particular by the taper 28 and the tapering area 32, can be clearly different from the illustrated courses 29, 30.

A slightly modified variant of a device 1 is in the FIGS. 6a and 6b shown in a sectional view and a plan view. The embodiment differs only in that instead of a closing element 6 and an ultrasonic generator 5 a contiguous drive unit 31 is provided which contains an ultrasonic generator and which can be screwed into the threaded bore 8 of the first part 3 of the Schallleitelements 2.

In the FIGS. 7a to 7c three different further embodiments of a contact surface 15 are shown in section and in a plan view. In the Figure 7a shown contact surface has four distributed over the circumference, at 90 ° angles to each other arranged intake ports 34, which are each connected to the channel 18. For this purpose, the channel is not performed up to the contact surface 15 as a central channel but divides into four connected to one of the openings each sub-channels 35. The channel 18 may initially be partially introduced into the second part 4 from the side of the second part facing the first part 3 by drilling. The introduced bore does not penetrate completely through the second part 4 and is thus formed as a blind hole. The sub-channels 35 can then be introduced starting from the contact surface 15, such that they end in the lower end of the blind hole.

The variant off Figure 7a can also be modified to the effect that the channel 18 (in particular of reduced cross-section) is carried to the contact surface 15. The suction ports 34 connected to the sub-channels 35 then act as additional suction points (in addition to a central opening 17 as seen in FIG FIG. 1 known) and improve uniformity of the pressure force of the membrane on the contact surface over the variant FIG. 1 ,

The variant off FIG. 7b has a continuous central channel 18, the same as in FIG. 1 is trained. Starting in a star-shaped manner from the opening 17, however, superficial channels 36 are incorporated into the contact surface 15. A height of the channels decreases here with increasing distance from the contact surface 15.

The variant off FIG. 7c also has a continuous channel 18 as shown FIG. 1 known on. In the contact surface are an annular channel 37th and connecting channels 38 incorporated. Of course, a plurality of annular channels 37 may be provided and also the number of connection channels 38 may be varied.

The variant off FIG. 7d also has a continuous channel 18. From this outgoing go from several main channels 39, which in turn branch off in hub channels 40. These in turn can branch out according to the principle of a self-similar structure, but this is not shown in the figure. The main channels 39, as can be seen from the sectional view, have a greater height than the secondary channels 40.

Claims (15)

Device (1) for applying liquid media with ultrasound through a membrane, wherein the device - An ultrasonic generator (5) for generating ultrasound and a sound conducting element (2) for guiding the ultrasound generated by the ultrasound generator,
and the sound conducting element (2) has a contact surface (15) for coupling the ultrasound to a flexible medium,
wherein the sound conducting element (2) comprises a channel (18) having a first opening (20) for applying negative pressure to the channel (18) and a second opening (17) for applying the negative pressure to the flexible material. Device (1) according to Claim 1, characterized in that the ultrasound generator (5) comprises at least one piezoelectric element (21, 22, 23, 24), the ultrasound generator (5) preferably having a plurality of piezoelectric elements (21, 22, 23, 24 ), wherein - At least a first piezoelectric element (21, 22) is connected to a power supply for vibrational excitation of the first piezoelectric element and - At least a second piezoelectric element (23, 24) with a measuring device for measuring the second piezoelectric element (23, 24) passing through ultrasound is connected. Device (1) according to one of the preceding claims, characterized in that the second opening (17) is arranged within the contact surface (15). Device (1) according to one of the preceding claims, characterized in that in the region of the contact surface (15) the contact surface (15) circumferential sealing element (16) is arranged and / or that the contact surface (15 ') to form a peripheral sealing edge concave is shaped. Device (1) according to one of the preceding claims, characterized in that the sound conducting element (2) has at least one tapered region (28). Device (1) according to one of the preceding claims, characterized in that the sound-conducting element (2) has at least one first part (3) connected to the ultrasound generator (5) and a second part (4) having the contact surface (15), wherein the two parts (3, 4) connected to each other, for example screwed, are. Device (1) according to claim 6, insofar as it relates to claim 5, characterized in that the tapered region (28) is arranged in the second part (4) having the abutment surface (15). Device (1) according to claim 6 or 7, characterized in that the channel (18) the first and the second part (3, 4) of the Schallleitelements (2) each at least partially through, wherein the first opening (20) of the channel in the first part (3) and the second opening (17) of the channel in the second part (4) is arranged. Device (1) according to one of the preceding claims, comprising a closing element (6) which forms the end of the device opposite the contact surface (15). Device according to one of the preceding claims, characterized in that the first part (3) made of a different material than the second part (4) and / or the closing element (6) is formed. Device (1) according to one of the preceding claims, characterized in that the ultrasound generator (5) for generating ultrasound is set up with a frequency between 20 kHz and 100 kHz, for example a frequency between 30 kHz and 40 kHz. Device (1) according to one of the preceding claims, characterized in that the first opening (20) of the channel (18) is arranged in a direction of emission of the ultrasound generator substantially orthogonally oriented side surface of the Schallleitelements. Comprising ultrasound system a device (1) according to one of the preceding claims, - A vacuum source, such as a pump, which is adapted to generate a negative pressure and connected to the channel (18). Ultrasound system according to claim 13, comprising a flexible material resting against the abutment surface (15), in particular a membrane resting against the abutment surface. Ultrasonic system according to one of claims 13 or 14, if this is related back to claim 8, comprising a plurality of mutually interchangeable second parts (4) of the Schallleitelements (2), wherein the interchangeable second parts (4) with respect to a cross-sectional area in the region of the taper (28 ) and / or with respect to the contact surface (15).

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