Efficient ultraviolet laser protection device and method

Abstract

The invention provides an efficient ultraviolet laser protection device and method, and belongs to the technical field of ultraviolet laser medical protection, the efficient ultraviolet laser protection device comprises an ultraviolet laser emitter, a light reflection isolation frame, an ultraviolet laser protection automatic control system, an ultraviolet grating protection layer and a reflection strip, the inner contour of the reflective isolation frame is a parallelogram similar to a rectangle, the inner contour of the reflective isolation frame is provided with two large angles and two small angles, and the first ultraviolet laser transmitter and the second ultraviolet laser transmitter are arranged on the two outer sides of one small angle of the reflective isolation frame respectively. And the third ultraviolet laser emitter and the fourth ultraviolet laser emitter are respectively arranged on two outer sides of the other small corner of the reflective isolation frame. According to the invention, the air transmission path of pathogens between people can be quickly and efficiently cut off at low cost, and the device has good isolation and disinfection effects when being used in medical outpatient service, sickrooms or patient families.

Description

Technical Field

[0001] The invention relates to the technical field of ultraviolet laser medical protection, and in particular to a highly efficient ultraviolet laser protection device and method. Background Art

[0002] During the outbreak of malignant respiratory infectious diseases, airborne transmission between doctors and patients, and between patients and their families will cause a large-scale cross-infection, which is extremely detrimental to the control of malignant respiratory infectious diseases. Traditional medical protective equipment includes masks, gloves, isolation gowns, goggles, etc. These protective equipment are very inconvenient to wear and use, and most of them are disposable, which not only seriously affects the physical and mental health of doctors and patients, but also causes serious consumption of medical resources.

[0003] Ultraviolet sterilization and disinfection technology for medical protection achieves the disinfection effect by irradiating pathogens (including bacteria, viruses, spores, etc.), destroying the function of pathogen nucleic acid, changing the biological activity of pathogen DNA, making pathogens unable to replicate themselves, and causing lethal damage to pathogens. The wavelength range of ultraviolet rays is usually between 100 and 400nm. When killing pathogens, the strongest band is 250-270nm, and the irradiation killing dose is not less than 0.1W·s / cm 2 At present, the commonly used 30W ultraviolet disinfection scattered light lamp usually has an ultraviolet radiation intensity of only 70μW / cm at a distance of 1 meter from the light source. 2 It takes 30 minutes of irradiation to completely kill bacteria and viruses. Low ozone ultraviolet germicidal lamps (ozone output <1mg / h) can be used for indoor air disinfection in human environments. Summary of the invention

[0004] The purpose of the present invention is to provide an efficient ultraviolet laser protection device and method, which can quickly, efficiently and low-costly cut off the airborne transmission of pathogens between people. When used in medical clinics, wards or patients' homes, it will have good isolation and disinfection effects.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] In the first aspect, a high-efficiency ultraviolet laser protection device is characterized in that it includes an ultraviolet laser emitter, a reflective isolation frame, an ultraviolet laser protection automatic control system, an ultraviolet grating protection layer and a reflective strip, the outer contour of the reflective isolation frame is a rectangle, the inner contour of the reflective isolation frame is a parallelogram approximately rectangular, the inner contour of the reflective isolation frame has two large angles and two small angles, the ultraviolet laser emitter includes a first ultraviolet laser emitter, a second ultraviolet laser emitter, a third ultraviolet laser emitter and a fourth ultraviolet laser emitter, the first ultraviolet laser emitter and the second ultraviolet laser emitter are respectively arranged on the outer sides of a small angle of the reflective isolation frame, and the third ultraviolet laser emitter and the fourth ultraviolet laser emitter are respectively arranged on the outer sides of another small angle of the reflective isolation frame.

[0007] The ultraviolet laser protection automatic control system includes a screen display control actuator and a photosensitive telescopic probe. The screen display control actuator is fixedly built into the upper right end of the reflective isolation frame, and the photosensitive telescopic probe is arranged near the top large angle of the reflective isolation frame. The wires and sensor lines of the ultraviolet laser emitter and the photosensitive telescopic probe are connected to the screen display control actuator. When the ultraviolet laser emitters are turned on at the same time, an ultraviolet grating protection layer is formed inside the reflective isolation frame. Reflective strips are arranged around the reflective isolation frame except for the ultraviolet laser emitter, and a narrow laser incident port is opened in the reflective strip.

[0008] Furthermore, the ultraviolet laser emitter is a low-ozone ultraviolet laser generator. When the four ultraviolet laser emitters work simultaneously, the ozone output is <1 mg / h. The low-ozone ultraviolet laser generator can emit a long strip of ultraviolet light. The width of the long strip of ultraviolet light is 1 to 2 mm, the length L is 35 to 200 mm, and the wavelength of the ultraviolet laser is 250 to 270 nm.

[0009] Furthermore, the irradiation intensity of the ultraviolet light is 0.2 to 0.5 W·s / cm 2 .

[0010] Furthermore, the reflective isolation frame reflects the ultraviolet laser 24 to 34 times.

[0011] Furthermore, the frame height of the reflective isolation frame does not exceed 3m, the frame span does not exceed 3.5m, the width of the reflective strip inside the reflective isolation frame is not less than 20mm, and the minimum ultraviolet light intensity of a UV grating is not less than 0.1W / cm 2 .

[0012] Furthermore, the light reflectivity of the reflective strip is not less than 99%.

[0013] In a second aspect, the present application provides an efficient ultraviolet laser protection method, comprising the following steps:

[0014] 1) When a UV laser transmitter is turned on, the UV laser is spread along one of the hypotenuses of the parallelogram to the opposite side, and is reflected back to the side where the UV light source is located. By adjusting the incident angle, it is ensured that there is exactly 1 / 2 overlap between the reflected light and the incident light. At this time, the distance that the parallelogram isolation frame deviates from the rectangular frame is exactly half the length of the incident beam.

[0015] 2) After multiple reflections, the ultraviolet light completely covers the inside of the entire parallelogram frame without any gaps, ensuring that pathogens in the air can only enter the isolation area by passing through the ultraviolet light. The thickness of this ultraviolet grating is 1 to 2 mm.

[0016] 3) When a large foreign object, such as an arm, passes through the UV grating, the backlight area of ​​the arm becomes a blind spot for UV light, and the UV grating completely loses its protective function. At this time, if the UV laser light source on the opposite side is turned on, there will be no blind spot. When four UV laser light sources are turned on at the same time, four UV gratings can be formed, and the spacing between two adjacent UV gratings is 2 to 3 mm. Even if a person passes through these four UV gratings, the UV gratings will not lose their protective function.

[0017] 4) The ultraviolet protection of the ultraviolet laser protection automatic control system is divided into four levels, corresponding to the first, second, third and fourth layers of ultraviolet protection gratings. The photosensitive telescopic probe measures the intensity of the ultraviolet grating every 1 hour during illumination, and can display the change curve of the illumination intensity of the four ultraviolet protection gratings with the illumination time on the screen display control actuator. When the illumination intensity of the ultraviolet grating drops to 75% of the initial value, the screen alarm prompts that the ultraviolet light source needs to be replaced. The ultraviolet laser protection automatic control system can automatically adjust the illumination time of the four ultraviolet gratings through the screen display control actuator, so that the illumination intensity of the four keeps changing synchronously, and finally realizes the synchronous replacement of four new ultraviolet light sources.

[0018] Advantages of the present invention:

[0019] 1. The operation is simple. You only need to press the on / off key on the screen control actuator of the UV laser protection device, and then select the protection level to start the protection function immediately.

[0020] 2. Easy maintenance. The UV laser protection automatic control system can automatically adjust the illumination time of four UV gratings and realize the synchronous replacement of four new UV light sources.

[0021] 3. High efficiency inactivation: UV grating is formed by multiple reflections of UV laser, which greatly reduces the protection cost of UV grating. In addition, UV grating has high light intensity and can instantly inactivate germs in the air.

[0022] 4. Comfortable isolation, the indoor air is naturally circulated, and the UV grating can reduce the concentration of pathogens in the indoor air to an extremely low level. Doctors, patients and their families usually do not need to wear masks, goggles and other protective equipment in this environment, thus creating a harmonious medical environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the present invention;

[0024] Figure 2 The schematic diagram of the formation of the ultraviolet grating protective layer of the present invention;

[0025] In the figure: 1. a first ultraviolet laser emitter, 2. a second ultraviolet laser emitter, 3. a third ultraviolet laser emitter, 4. a fourth ultraviolet laser emitter, 5. a screen display control actuator, 6. a reflective isolation frame, 7. a photosensitive telescopic probe, 8. an ultraviolet grating protective layer, and 9. a reflective strip. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention.

[0027] like Figure 1 As shown, a high-efficiency ultraviolet laser protection device includes an ultraviolet laser emitter, a reflective isolation frame 6, an ultraviolet laser protection automatic control system, an ultraviolet grating protection layer 8 and a reflective strip 9, the outer contour of the reflective isolation frame 6 is a rectangle, the inner contour of the reflective isolation frame 6 is a parallelogram approximately rectangular, the inner contour of the reflective isolation frame 6 has two large angles and two small angles, the ultraviolet laser emitter includes a first ultraviolet laser emitter 1, a second ultraviolet laser emitter 2, a third ultraviolet laser emitter 3 and a fourth ultraviolet laser emitter 4, the first ultraviolet laser emitter 1 and the second ultraviolet laser emitter 2 are respectively arranged on the outer sides of a small angle of the reflective isolation frame 6, and the third ultraviolet laser emitter 3 and the fourth ultraviolet laser emitter 4 are respectively arranged on the outer sides of another small angle of the reflective isolation frame 6.

[0028] The ultraviolet laser protection automatic control system includes a screen display control actuator 5 and a photosensitive telescopic probe 7. The screen display control actuator 5 is fixedly built into the upper right end of the reflective isolation frame 6. The photosensitive telescopic probe 7 is arranged near the top large angle of the reflective isolation frame 6. The wires and sensor lines of the ultraviolet laser emitter and the photosensitive telescopic probe 7 are connected to the screen display control actuator 5. When the ultraviolet laser emitters are turned on at the same time, an ultraviolet grating protection layer 8 is formed inside the reflective isolation frame 6. Reflective strips 9 are arranged around the reflective isolation frame 6 except for the ultraviolet laser emitter, and a narrow laser incident port is opened in the reflective strips 9.

[0029] As a preferred embodiment of the present invention, the ultraviolet laser emitter is a low ozone ultraviolet laser generator. When the four ultraviolet laser emitters work simultaneously, the ozone output is

[0030] <1mg / h, the low ozone ultraviolet laser generator can emit a long strip of ultraviolet light, the width of the long strip of ultraviolet light is 1-2mm, the length L is 35-200mm, and the wavelength of the ultraviolet laser is 250-270nm, preferably 253.7nm.

[0031] As a preferred embodiment of the present invention, the irradiation intensity of the ultraviolet light is 0.2-0.5 W·s / cm 2 , pathogens are killed in less than 1 second under ultraviolet laser irradiation.

[0032] As a preferred embodiment of the present invention, the reflective isolation frame 6 reflects the ultraviolet laser 24 to 34 times. Calculated based on a reflectivity of 99%, the ultraviolet laser irradiation intensity drops to 78% and 71% of the initial value after 24 and 34 reflections, respectively.

[0033] As a preferred embodiment of the present invention, the frame height of the reflective isolation frame 6 does not exceed 3m, the frame span does not exceed 3.5m, the width of the reflective strip 9 inside the reflective isolation frame 6 is not less than 20mm, and the minimum ultraviolet light intensity of a UV grating is not less than 0.1W / cm 2 .

[0034] As a preferred embodiment of the present invention, the light reflectivity of the reflection strip 9 is not less than 99%.

[0035] like Figure 2 As shown, the UV grating protective layer is a parallelogram that is close to a rectangle. The length of the base is b, the length of the incident light beam is L, b is 12 to 17 times of L, the incident light angle is close to vertical, the length of the hypotenuse is a, which is approximately equal to the height, and a and b are not much different. In order to clearly reflect the formation principle of the grating protective layer, Figure 2b is only 3 times of L, and both a and b are greatly shortened. The laser protection layer is formed by multiple reflections of the laser beam on the reflective strip of the protection frame to form a dense ultraviolet grating. The arrows indicate the direction of the light. The incident beam and the reflected beam form an overlapping area, and the dark color area is the overlapping area. When the overlapping area is a·L / 2, the ultraviolet grating just completely covers the entire parallelogram area with the least number of reflections. At this time, the distance that the parallelogram deviates from the rectangle is exactly L / 2.

[0036] The steps of the embodiment device for ultraviolet laser protection are as follows:

[0037] 1) When a UV laser transmitter is turned on, the UV laser is spread along one of the hypotenuses of the parallelogram to the opposite side, and is reflected back to the side where the UV light source is located. By adjusting the incident angle, it is ensured that there is exactly 1 / 2 overlap between the reflected light and the incident light. At this time, the distance that the parallelogram isolation frame deviates from the rectangular frame is exactly half the length of the incident beam.

[0038] 2) After multiple reflections, the ultraviolet light completely covers the inside of the entire parallelogram frame without any gaps, ensuring that pathogens in the air can only enter the isolation area by passing through the ultraviolet light. The thickness of this ultraviolet grating is 1 to 2 mm.

[0039] 3) When a large foreign object, such as an arm, passes through the UV grating, the backlight area of ​​the arm becomes a blind spot for UV light irradiation, and the UV grating completely loses its protective effect; at this time, if the UV laser light source on the opposite side is turned on, there will be no blind spot. When four UV laser light sources are turned on at the same time, four UV gratings can be formed, and the spacing between two adjacent UV gratings is 2 to 3 mm. Even if a person passes through these four UV gratings, the UV gratings will not lose their protective effect.

[0040] 4) The ultraviolet protection of the ultraviolet laser protection automatic control system is divided into four levels, corresponding to the first, second, third and fourth layers of ultraviolet protection gratings respectively. The photosensitive telescopic probe 7 measures the intensity of the ultraviolet grating every 1 hour during illumination, and can display the change curve of the illumination intensity of the four ultraviolet protection gratings with the illumination time on the screen display control actuator 5. When the illumination intensity of the ultraviolet grating drops to 75% of the initial value, the screen will alarm to prompt the need to replace the ultraviolet light source; the ultraviolet laser protection automatic control system can automatically adjust the illumination time of the four ultraviolet gratings through the screen display control actuator 5, so that the illumination intensity of the four keeps changing synchronously, and finally realizes the synchronous replacement of four new ultraviolet light sources.

[0041] Application of the embodiment:

[0042] 1) Build a set of ultraviolet light isolation and protection equipment in the fever clinic of the hospital. The height of the outpatient ward is 300 cm, the width is 350 cm, and the length is 700 cm. The isolation and protection frame is a rectangular frame of 300 cm × 350 cm. The parallelogram reflection frame inside the frame is 250 cm high and 300 cm wide. Four low-ozone ultraviolet laser emitters are used as light sources, and the ultraviolet light intensity is 0.5W / cm 2 , the reflectivity of the reflective strip is 99%, and the width of the reflective strip is 20 mm. On the upper and lower sides, the width of each beam of ultraviolet light is 1 mm, the length L is 170 mm, and the ultraviolet light is reflected 34 times. On the left and right sides, the width of each beam of ultraviolet light is 1 mm, the length L is 200 mm, and it is reflected 24 times. The isolation protection frame deviates from the rectangular frame by 85 mm, and a total of four layers of isolation protection gratings are produced, with a spacing of 3 mm between adjacent gratings. Level 1 protection is used for daily medical treatment, and only one reflective grating is opened. During major outbreaks, level 4 protection is adopted, and the upper and lower and left and right reflective gratings are opened at the same time. The total laser power emitted by the four low-ozone ultraviolet laser transmitters is 3.7W, the electro-optical conversion efficiency of the ultraviolet laser transmitter is 20%, and the total power consumption is 18.5W.

[0043] 2) In the infectious disease ward of the hospital, a set of ultraviolet light isolation and protection devices is built around the bed. The width of the bed is 120 cm and the length is 200 cm. A 130cm×210cm×210cm rectangular frame is built around the bed. The top of the frame is completely sealed, and the frame fits the wall completely. A laser protection layer is formed on three sides around the bed. 12 low-ozone ultraviolet laser transmitters are used as light sources, and the ultraviolet light intensity is 0.3W·s / cm 2 , the reflectivity of the reflective strip is 99%, and the width of the reflective strip is 25 mm. Among them, the two opposite parallelogram inner frames are the same, with a height of 160 cm and a width of 160 cm. The width of the ultraviolet beam is 2 mm and the length is 100 mm. The number of reflections on the upper and lower surfaces and the left and right surfaces is 30 times, and it contains 4 parallel gratings. The height a of the parallelogram inner frame facing the other wall is still 160 cm, but the width b is only 80 cm, and a and b are twice as much. In this case, special design is required. On the upper and lower surfaces and the left and right surfaces, the ultraviolet beam is 2 mm wide and 50 mm long. On the upper and lower surfaces, the two gratings are parallel gratings with 30 reflections. On the left and right surfaces, the two gratings completely overlap, and each grating reflects 60 times. A total of three layers of isolation protection gratings are generated. The first-level protection is used for daily protection, and only the two reflective gratings on the left and right surfaces are opened. During major sudden epidemics, the third-level protection is adopted, and the upper and lower surfaces and the left and right reflective gratings are opened at the same time. The total laser power emitted by 12 low-ozone ultraviolet laser transmitters is 6.0W, the electro-optical conversion efficiency of the ultraviolet laser transmitter is 20%, and the total power consumption is 30W.

[0044] 3) The patient was isolated in a sunny bedroom at home. There was a door between the bedroom and the living room. The door frame was 210 cm high and 90 cm wide. There was no obstruction within 30 cm around the door frame. The isolation protection frame was a rectangular frame of 240 cm × 145 cm. The parallelogram reflection frame inside the frame was 190 cm high and 95 cm wide. Four identical low-ozone ultraviolet laser transmitters were used as light sources. The ultraviolet light intensity was 0.2 W·s / cm 2 The width of the light beam is 2mm and the length is 60mm. The reflectivity of the reflection strip is 99%, and the width of the reflection strip is 20mm. Two units are used for left and right reflection, with 34 reflections, forming two layers of parallel fan planes. The other two beams are used for upper and lower surface reflections, with 68 reflections, forming one layer of fan plane. The isolation protection frame deviates from the rectangular frame by 30mm, producing a total of three layers of isolation protection gratings, and the spacing between adjacent gratings is 3mm. Three-level protection is adopted, and the upper and lower and left and right reflection gratings are opened at the same time. The total laser power emitted by the four low-ozone ultraviolet laser transmitters is 0.96W, the electro-optical conversion efficiency of the ultraviolet laser transmitter is 20%, and the total power consumption is 4.8W.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can still adjust the technical solutions described in the above embodiments or replace some of the technical features by equivalents. Therefore, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. An efficient ultraviolet laser protection device, characterized in that: The invention comprises an ultraviolet laser emitter, a reflective isolation frame (6), an ultraviolet laser protection automatic control system, an ultraviolet grating protection layer (8) and a reflective strip (9), wherein the outer contour of the reflective isolation frame (6) is a rectangle, the inner contour of the reflective isolation frame (6) is a parallelogram approximately similar to a rectangle, the inner contour of the reflective isolation frame (6) has two large angles and two small angles, the ultraviolet laser emitter comprises a first ultraviolet laser emitter (1), a second ultraviolet laser emitter (2), a third ultraviolet laser emitter (3) and a fourth ultraviolet laser emitter (4), the first ultraviolet laser emitter (1) and the second ultraviolet laser emitter (2) are respectively arranged on the outer sides of a small angle of the reflective isolation frame (6), and the third ultraviolet laser emitter (3) and the fourth ultraviolet laser emitter (4) are respectively arranged on the outer sides of another small angle of the reflective isolation frame (6); The ultraviolet laser protection automatic control system comprises a screen display control actuator (5) and a photosensitive telescopic probe (7). The screen display control actuator (5) is fixedly built into the upper right end of the reflective isolation frame (6). The photosensitive telescopic probe (7) is arranged near the top large angle of the reflective isolation frame (6). The wires and sensor lines of the ultraviolet laser emitter and the photosensitive telescopic probe (7) are connected to the screen display control actuator (5). When the ultraviolet laser emitters are turned on at the same time, an ultraviolet grating protection layer (8) is formed inside the reflective isolation frame (6). Reflective strips (9) are arranged around the reflective isolation frame (6) except for the ultraviolet laser emitter, and a narrow laser incident port is opened in the reflective strip (9).

2. The highly efficient ultraviolet laser protection device according to claim 1, characterized in that: The ultraviolet laser emitter is a low-ozone ultraviolet laser generator. When the four ultraviolet laser emitters work simultaneously, the ozone output is <1 mg / h. The low-ozone ultraviolet laser generator can emit a long strip of ultraviolet light. The width of the long strip of ultraviolet light is 1 to 2 mm, the length L is 35 to 200 mm, and the wavelength of the ultraviolet laser is 250 to 270 nm.

3. An efficient ultraviolet laser protection device according to claim 2, characterized in that: The irradiation intensity of the ultraviolet light is 0.2-0.5 W·s / cm 2 .

4. The highly efficient ultraviolet laser protection device according to claim 3, characterized in that: The reflective isolation frame (6) reflects the ultraviolet laser 24 to 34 times.

5. The highly efficient ultraviolet laser protection device according to claim 4, characterized in that: The frame height of the reflective isolation frame (6) does not exceed 3m, the frame span does not exceed 3.5m, the width of the reflective strip (9) inside the reflective isolation frame (6) is not less than 20mm, and the minimum ultraviolet light intensity of a UV grating is not less than 0.1W / cm 2 .

6. The highly efficient ultraviolet laser protection device according to claim 5, characterized in that: The light reflectivity of the reflection strip (9) is not less than 99%.

7. An efficient ultraviolet laser protection method, using an efficient ultraviolet laser protection device as claimed in claim 1, characterized in that: The following steps are involved: 1) When a UV laser transmitter is turned on, the UV laser is spread along one of the hypotenuses of the parallelogram to the opposite side, and is reflected back to the side where the UV light source is located. By adjusting the incident angle, it is ensured that there is exactly 1 / 2 overlap between the reflected light and the incident light. At this time, the distance that the parallelogram isolation frame deviates from the rectangular frame is exactly half the length of the incident beam; 2) After multiple reflections, the ultraviolet light completely covers the inside of the parallelogram frame without any gaps, ensuring that pathogens in the air can only enter the isolation area by passing through the ultraviolet light. The thickness of this ultraviolet grating is 1 to 2 mm; 3) When a large foreign object, such as an arm, passes through the UV grating, the backlight area of ​​the arm becomes a blind spot for UV light, and the UV grating completely loses its protective function. At this time, if the UV laser light source on the opposite side is turned on, there will be no blind spot. When four UV laser light sources are turned on at the same time, four UV gratings can be formed, and the spacing between two adjacent UV gratings is 2 to 3 mm. Even if a person passes through these four UV gratings, the UV gratings will not lose their protective function. 4) The ultraviolet protection of the ultraviolet laser protection automatic control system is divided into four levels, corresponding to the first, second, third and fourth layers of ultraviolet protection gratings respectively. The photosensitive telescopic probe (7) measures the intensity of the ultraviolet grating every 1 hour during illumination, and can display the change curve of the illumination intensity of the four ultraviolet protection gratings with the illumination time on the screen display control actuator (5). When the illumination intensity of the ultraviolet grating drops to 75% of the initial value, the screen displays an alarm prompting that the ultraviolet light source needs to be replaced; the ultraviolet laser protection automatic control system can automatically adjust the illumination time of the four ultraviolet gratings through the screen display control actuator (5), so that the illumination intensity of the four ultraviolet gratings keeps changing synchronously, and finally realizes the synchronous replacement of four new ultraviolet light sources.

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