Sodium alginate aromatic decompression ball containing essential oil nanoparticles and preparation method thereof

Abstract

The invention discloses a sodium alginate aromatic decompression ball containing essential oil nano-particles and a preparation method thereof, and relates to the technical field of emotion regulation article manufacturing, the aromatic decompression ball adopts a'shell-inner core 'double-layer structure, the outer layer is a spherical shell made of a sodium alginate material, and the inner core is a spherical shell made of an essential oil nano-particle. Essential oil nano-particles with a polylactic acid-glycolic acid copolymer as a carrier are uniformly dispersed in the product, long-acting stable release of natural plant essential oil fragrance is realized through a dual controlled release mechanism of PLGA nano-microsphere embedding and sodium alginate shell wrapping, the product integrates dual functions of touch extrusion decompression and olfactory aromatic therapy and healing, and the product has a wide application prospect. According to the present invention, the raw materials of the product have characteristics of good biocompatibility, good natural degradability, no harmful substance residue, safe contact with the human body, natural degradation after discarding, environmental protection, and high practical application value, and can be used for assisting the alleviation of the anxiety, the fatigue, the insomnia and other emotion problems through the pinching and holding tactile stimulation and the aroma effect of the essential oil, and the raw materials of the product have characteristics of good biocompatibility, good natural degradability, no harmful substance residue, and safety in contact with the human body, and can be naturally degraded after being discarded.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mood regulation product manufacturing, in particular to a sodium alginate fragrance decompression ball containing essential oil nanoparticles and a preparation method thereof. BACKGROUND

[0002] The decompression ball is a functional product that realizes pressure release through a "pinching" action. Its core function is to help users relieve psychological pressure and release emotions through tactile stimulation. It is widely used in daily decompression and mood regulation. An ideal functional decompression ball should have the following characteristics: ① excellent safety, environmentally friendly and non-toxic material, no harmful substance residue, friendly to sensitive groups (especially children and skin sensitive people); ② multiple functions, in addition to basic tactile decompression, additional functions such as fragrance can be combined to enhance the sense of pleasure; ③ good stability, the material is not easy to absorb moisture and stick, and adsorb odors, the additional function (such as fragrance) can be kept for a long time; ④ good environmental compatibility, no harm to the environment after production and disposal, can be naturally degraded or harmlessly treated.

[0003] In the current market, the core preparation materials of traditional decompression balls are mainly silicone or polyvinyl chloride (PVC), but these two types of materials have significant shortcomings in safety, functionality and environmental compatibility: for silicone material, it is easy to leave chemical impurities such as vulcanizing agent and low molecular silicone oil during production and processing, which may cause skin itching, redness and other discomfort symptoms in special groups such as children and skin sensitive people; at the same time, silicone has a porous structure, not only new products often have a distinct "plastic smell", but also easily adsorb environmental odors, and long-term use will further exacerbate the problem of odor adsorption due to moisture absorption and stickiness, seriously affecting user experience; as for PVC material, in order to achieve the required softness and elasticity of the product and stability during processing, a large amount of plasticizer (to improve material flexibility) and stabilizer (to prevent material decomposition during processing) is added during production, among which the plasticizer is easy to enter the human body through skin contact or children's mis-eating, and long-term contact may interfere with the endocrine system, especially causing potential risks to the normal growth and development of children; in addition, PVC material is difficult to degrade in the natural environment, and if it is treated by incineration after disposal, it will also produce toxic and harmful pollutants such as dioxin, causing serious harm to the ecological environment.

[0004] To improve the product experience, the current market with aroma function of decompression ball (commonly known as "pinch ball"), the realization of the aroma function is to add chemical fragrance directly to the base material, but this scheme has significant defects in practical application: first, the aroma persistence is poor, because the chemical fragrance is not stabilized before mixing with the decompression ball substrate, it is easy to be affected by environmental temperature, air flow and other factors, and quickly volatilize and lose, usually the product can only maintain the aroma for about a week, it is difficult to meet the user's demand for long-term aroma experience; second, the safety is questionable, some chemical fragrances may contain harmful chemicals such as formaldehyde, and some manufacturers may add too much fragrance to achieve a rich aroma effect, which may cause the product to exceed the formaldehyde content, and long-term contact with such products may cause conjunctivitis, skin allergy and other health problems, which makes such aromatic decompression balls unsuitable for special user groups such as children and people with sensitive skin.

[0005] Natural plant essential oil is an ideal choice to replace chemical fragrance: it is derived from natural plants, which is safer for human body and environment than chemical fragrance, and different essential oils (such as lavender essential oil for soothing effect, lemon essential oil for refreshing effect) can give the product specific functional experience, and it also has the natural property of long-lasting aroma. However, natural plant essential oil has inherent defects of easy volatilization and strong heat sensitivity, and when using traditional direct addition method, it is easy to cause poor stability and easy loss of active ingredients (aroma and functional ingredients) due to temperature changes during processing and rapid volatilization during use, which greatly limits its application in decompression ball products.

[0006] Therefore, there is an urgent need in the art to develop a functional decompression ball with safety and environmental protection, multiple functions (touch + long-lasting aroma) and stable and durable characteristics, to solve the problems of traditional material hazards, chemical fragrance risks and natural essential oil application bottlenecks through innovative technology, and to meet the needs of consumers for safe, long-lasting and multi-functional decompression products. SUMMARY

[0007] The present application provides a sodium alginate aroma decompression ball containing essential oil nanoparticles and a preparation method and application thereof, which solves the problems of insufficient human contact safety, high environmental pollution risk of traditional decompression balls (silicone, PVC material), and rapid release of aroma and short-lasting aroma of traditional aroma decompression balls.

[0008] To achieve the above-mentioned purposes, the technical scheme adopted by the present application is as follows: The application discloses a sodium alginate fragrance decompression ball containing essential oil nanoparticles, which comprises an outer shell and an internal functional component; the outer shell is made of sodium alginate and forms a closed or semi-closed spherical structure; the internal functional component is essential oil nanoparticles which are dispersed in a cavity in the outer shell and are loaded with natural plant essential oil in a polylactic acid-glycolic acid copolymer (PLGA) carrier.

[0009] The application further provides a preparation method of the sodium alginate fragrance decompression ball containing essential oil nanoparticles. (1) polyvinyl alcohol (PVA) is added to water, heated and stirred until completely dissolved to obtain water phase 1; Preferably, the mass fraction of the PVA in the water phase 1 is 1.5-3%.

[0010] (2) the water phase 1 is diluted 10 times with deionized water, and stirred uniformly to obtain water phase 2; Preferably, the mass fraction of the PVA in the water phase 2 is 0.15-0.3%.

[0011] (3) polylactic acid-glycolic acid copolymer (PLGA) and natural plant essential oil are added to dichloromethane, and stirred until completely dissolved to obtain an oil phase; Preferably, the molar ratio of the PLGA to the essential oil is 1:0.1-0.5; Preferably, the mass fraction of the PLGA in the oil phase is 0.5-2%.

[0012] (4) the oil phase prepared in the step (3) is slowly added to the water phase 1 in the step (1), and ultrasonic treatment is adopted to form a uniform and stable emulsion 1; Preferably, the power of the ultrasonic treatment is 150-300 W, and the ultrasonic time is 5-10 min.

[0013] (5) the emulsion 1 is uniformly and slowly injected into the water phase 2 prepared in the step (2) at a constant rate, and stirring is conducted during the injection to form an emulsion 2; the emulsion 2 is placed in an environment at room temperature of 25-30 DEG C in an open state, and stirring is continuously conducted for 12 h, so that dichloromethane is fully volatilized to obtain uniformly dispersed essential oil nanoparticles; Preferably, the volume ratio of the emulsion 1 to the water phase 2 is 1:3-5; Preferably, the injection rate of the emulsion 1 into the water phase 2 is 0.5-1 mL / min; Preferably, the stirring rate of the emulsion 2 is 800-1500 rpm.

[0014] (6) calcium chloride (CaCl2) is added to deionized water, and stirred until completely dissolved to obtain water phase 3; Preferably, the mass fraction of CaCl2 in the aqueous phase 3 is 4-5%.

[0015] (7) Sodium alginate is added to deionized water, heated and stirred at 40-60 DEG C for 12h, until the sodium alginate is completely dissolved and a uniform transparent sodium alginate hydrogel is formed; Preferably, the heating temperature is 40-60 DEG C; Preferably, the mass fraction of sodium alginate in the hydrogel is 2.5-3%.

[0016] (8) The sodium alginate hydrogel prepared in step (7) is poured into a pre-set spherical mold, and the essential oil nanoparticles prepared in step (5) are uniformly injected into the center area of the hydrogel in the mold using a syringe; then the mold containing the essential oil nanoparticle-containing hydrogel is immersed in the aqueous phase 3 of step (6), and after standing for preliminary curing, the mold is removed to obtain a spherical sodium alginate blank containing essential oil nanoparticles; the blank is further placed in the aqueous phase 3 for secondary curing, and after curing, it is fished out and washed with deionized water to remove the residual CaCl2 solution on the surface, thereby obtaining an essential oil nanoparticle-containing sodium alginate fragrance decompression ball; Preferably, for the preparation of a spherical sodium alginate blank with a diameter of 5cm, the total curing time in the aqueous phase 3 should be no less than 12h.

[0017] The application also provides an essential oil nanoparticle-containing sodium alginate fragrance decompression ball prepared by the above preparation method, which is a regular sphere, has a dense sodium alginate gel layer as the shell, and has essential oil nanoparticles uniformly dispersed in the interior, with a particle size of 50-200nm.

[0018] The application further provides an application of the above essential oil nanoparticle-containing sodium alginate fragrance decompression ball in the field of mood regulation, which realizes the effects of soothing mood and relieving stress through the slow release of the aromatic odor of essential oil.

[0019] Compared with the prior art, the application has the following beneficial effects (1) Excellent safety and environmental protection: the core materials of the fragrance decompression ball of the application are all human-friendly and naturally degradable - the shell is made of natural sodium alginate, without residues such as vulcanizing agent and low molecular weight silicone oil; the essential oil nanoparticles in the interior are loaded with pure natural plant essential oil in biocompatible PLGA, avoiding the risk of traditional chemical fragrance containing formaldehyde and other harmful substances; at the same time, PLGA, sodium alginate and plant essential oil can be completely degraded in the natural environment, solving the problem of environmental pollution caused by the difficulty of degrading PVC materials and the generation of dioxins by incineration, and being suitable for various groups of people such as children and people with sensitive skin.

[0020] (2) Long-acting slow release of fragrance: The present application realizes the stable release of essential oil in stages through the double controlled release structure of "PLGA nanosphere embedding + sodium alginate shell wrapping". The PLGA nanosphere slowly releases essential oil through its own degradation, and the sodium alginate shell further delays the volatilization rate of essential oil. Under the room temperature (25-30℃) and standard atmospheric pressure (101.325kPa) environment, the effective release period of essential oil can reach more than 30 days, which is significantly longer than the traditional direct addition of chemical fragrance (the fragrance lasts about 1 week), breaks through the technical bottleneck of "short-acting instantaneous release", and realizes the long-term stable fragrance decompression effect.

[0021] (3) Stable and controllable preparation process: The preparation method of the present application adopts mature processes such as ultrasonic emulsification and gradient curing, and the parameters of each step (such as ultrasonic power, stirring rate and curing time) are clear and quantifiable. The essential oil nanoparticles obtained have uniform particle size (50-200nm), the fragrance decompression ball has good formability and controllable size (the diameter can be adjusted by a mold), is suitable for industrial mass production, and has good practical application value. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a structure schematic diagram of the sodium alginate fragrance decompression ball containing essential oil microspheres of the present application and a partial enlarged view of the internal essential oil nanoparticles; Figure 2 It is a transmission electron microscope (TEM) photo of essential oil nanoparticles; Figure 3 It is a dynamic light scattering (DLS) particle size distribution diagram of essential oil nanoparticles; Figure 4 It is a comparison diagram of infrared spectra of natural plant essential oil and essential oil nanoparticles prepared by the present application at different storage times; Figure 5 It is a photo of the sodium alginate decompression ball shell; Figure 6 It is a use schematic diagram of the fragrance decompression ball; Figure 1 Middle: 1, essential oil nanoparticle-containing cavity inside the decompression ball; 2, sodium alginate shell; 3, essential oil nanoparticles; A, partial enlarged area of the essential oil nanoparticle-containing cavity, used to clearly show the structure of the essential oil nanoparticle-containing cavity inside the decompression ball and the morphological distribution of the 3 essential oil nanoparticles in the cavity; Figure 4In the diagram: curves a, b, and c correspond to the infrared spectra of essential oil nanoparticles after 0, 15, and 30 days of storage, respectively; curve d is the infrared spectrum of blank PLGA microspheres (i.e., the carrier material for preparing essential oil nanoparticles) without essential oil coating; and curves g, e, and f correspond to the infrared spectra of pure natural plant essential oils after 7, 0, and 3 days of storage, respectively. It is known that the characteristic absorption band of essential oils is 300-400 nm, and a characteristic absorption peak exists at 320 nm. By comparison, it can be seen that the intensity of the characteristic peak at 320 nm of pure essential oils (curves g, e, and f) significantly decreases with prolonged storage time, while the intensity of the characteristic peak at 320 nm of essential oil nanoparticles (curves a, b, and c) remains basically stable within 30 days. This proves that the essential oil nanoparticles of this invention can effectively inhibit essential oil volatilization and achieve long-term retention. Detailed Implementation

[0023] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0024] Example Please see Figures 1-6 The present invention provides a technical solution: It is worth noting that the raw materials used in this invention are all commercially available products.

[0025] Example 1 1. Preparation of raw materials: Polyvinyl alcohol (PVA), natural lavender essential oil, polylactic acid-glycolic acid copolymer (PLGA, lactic acid:glycolic acid = 50:50), dichloromethane, calcium chloride (CaCl2), sodium alginate, and deionized water.

[0026] 2. Preparation method: (1) Preparation of aqueous phase 1: PVA was added to deionized water, heated to 50°C, and stirred at 250 rpm for 12 h until completely dissolved. The mass fraction of PVA was controlled to be 2% to obtain aqueous phase 1. (2) Preparation of aqueous phase 2: Take aqueous phase 1, dilute it 10 times with deionized water, stir evenly, and obtain aqueous phase 2 with PVA mass fraction of 0.2%; (3) Preparation of oil phase: PLGA and lavender essential oil are added to dichloromethane and stirred until completely dissolved. The molar ratio of PLGA to essential oil is controlled at 1:0.3 and the mass fraction of PLGA is 1.2% to obtain the oil phase. (4) Preparation of emulsion 1: Add the oil phase to the aqueous phase 1 and sonicate at 200W power for 7 minutes to form emulsion 1; (5) Preparation of essential oil nanoparticles: inject emulsion 1 into water phase 2 at a rate of 0.7 mL / min, stir at 1100 rpm to form emulsion 2, stir at room temperature for 12 h, volatilize dichloromethane, and obtain essential oil nanoparticles; (6) Preparation of water phase 3 (cross-linking and curing liquid): add CaCl2 to deionized water and stir until completely dissolved, control the mass fraction of CaCl2 to be 4%, and obtain water phase 3; (7) Preparation of sodium alginate hydrogel: add sodium alginate to deionized water, heat and stir at 50°C for 12 h, control the mass fraction of sodium alginate to be 2.5%, and obtain uniform hydrogel; (8) Preparation of aromatic decompression ball: pour the hydrogel into a spherical mold with a diameter of 5 cm, inject essential oil nanoparticles, immerse in water phase 3 for curing for 6 h (only once), control the shell thickness to be 0.8 cm, and then wash with deionized water to obtain the product.

[0027] 3. Performance test results: Shell appearance: translucent spherical shape, no damage on the surface, and the overall thickness is thin; Flexibility and resilience: too soft, obvious deformation after pinching, and poor resilience (recovery time > 3 s); Compression resistance: tested by a compression testing machine, the shell cracked when pressed to 5 N (compression strength < 5 N), fragile, and weak in compression resistance;

[0028] Example 2 1. Preparation of raw materials: The same as Example 1.

[0029] 2. Preparation method: Steps (1) to (7) are the same as Example 1 (CaCl2 mass fraction 4%, sodium alginate mass fraction 2.5%); Step (8) adjustment: pour the hydrogel into a spherical mold with a diameter of 5 cm, increase the amount of hydrogel, inject essential oil nanoparticles, immerse in water phase 3 for curing for 6 h, control the shell thickness to be 1.6 cm, and the rest of the operation is the same as Example 1.

[0030] 3. Performance test results: Shell appearance: spherical shape, uniform thickness (1.6 cm), and smooth surface; Flexibility and resilience: softness is slightly soft, can be deformed after pinching, and slow recovery (recovery time 2-3 s); Compression resistance: the shell cracked when pressed to 8 N (compression strength 8 N), still fragile, and weak in compression resistance; Other performance: no discomfort when touched by children and skin sensitive people.

[0031] Example 3 1. Raw materials for preparation: The same as Example 1.

[0032] 2. Preparation method: Steps (1)-(7) are the same as Example 1 (CaCl2 mass fraction 4%, sodium alginate mass fraction 2.5%) Step (8) adjustment: pour the hydrogel into a spherical mold with a diameter of 5 cm, adjust the amount of hydrogel, inject the essential oil nanoparticles, and then immerse it in water phase 3 for a total curing time of 12 h (5 h of preliminary curing + 7 h of secondary curing), control the shell thickness to be 2.2 cm, and the rest of the operations are the same as Example 1.

[0033] 3. Performance test results: Shell appearance: translucent spherical, smooth surface, uniform thickness (2.2 cm), no deformation, cracks; Flexibility and resilience: soft and elastic when pinched, quickly recovered (excellent resilience) within 1-2 s after deformation; Compression resistance: no damage when pressed to 15 N (compression strength 15 N), not easy to break, strong compression resistance; Other performance: no discomfort for children and skin-sensitive individuals.

[0034] Example 4 1. Raw materials for preparation: The same as Example 1.

[0035] 2. Preparation method: Steps (1)-(5) are the same as Example 1; (6) Preparation of water phase 3: add CaCl2 to deionized water, stir until completely dissolved, control the mass fraction of CaCl2 to be 5%, obtain water phase 3; (7) Preparation of sodium alginate hydrogel: add sodium alginate to deionized water, heat and stir at 50°C for 12 h, control the mass fraction of sodium alginate to be 3%, obtain uniform hydrogel; (8) Preparation of aromatic decompression ball: pour the hydrogel into a spherical mold with a diameter of 5 cm, inject the essential oil nanoparticles, and then immerse it in water phase 3 for a total curing time of 12 h, control the shell thickness to be 2.0 cm, and the rest of the operations are the same as Example 4.

[0036] 3. Performance test results: Shell appearance: opaque milky white, hard texture, regular spherical shape; Flexibility and resilience: cannot be pinched with fingers (hardness > Shore D50), no obvious deformation, excellent resilience (instantly bounced back after slight pressing, no decompression touch); Compression resistance: no breakage when compressed to 25N (high compression resistance, but not meeting the requirement of decompression function); Other performance: no discomfort when touched by children or skin sensitive people.

[0037] Example 5: 1. Preparation of raw materials The same as Example 1.

[0038] 2. Preparation method Steps (1)-(7) are the same as Example 1 (CaCl2 mass fraction 4%, sodium alginate mass fraction 2.5%); Step (8) adjustment: pour the hydrogel into a spherical mold with a diameter of 5 cm, after injecting the essential oil nanoparticles, immerse it in water phase 3 for a total curing time of 12 h, control the shell thickness to be 2.1 cm, and the rest of the operation is the same as Example 4.

[0039] 3. Performance test results Shell appearance: translucent light yellow, smooth surface, regular spherical shape; Flexibility and resilience: soft and deformable when pinched (hardness Shore A 30-35), returns to original shape within 1.5 s after release, moderate elasticity and resilience, meets the "pinch decompression" requirement; compression resistance: no breakage when compressed to 12N (compression resistance 12N), not easy to break, no cracks after 100 consecutive pinches, can be repeatedly used; Other performance: no discomfort when touched by children or skin sensitive people.

[0040] The above description is only a specific embodiment of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features applied herein.

Claims

1. A sodium alginate aromatic stress-relieving ball containing essential oil nanoparticles, characterized in that, The aromatic stress-relieving ball includes an outer shell and internal functional components; the outer shell is made of sodium alginate and forms a closed or semi-closed spherical structure; the internal functional components are essential oil nanoparticles, which are dispersed in the chambers inside the outer shell, and the essential oil nanoparticles are loaded with natural plant essential oils using polylactic acid-glycolic acid copolymer (PLGA) as a carrier.

2. A method for preparing sodium alginate aromatic stress-relieving balls containing essential oil nanoparticles as described in claim 1, characterized in that, Includes the following steps: (1) Add polyvinyl alcohol (PVA) to water, heat and stir to completely dissolve PVA, and obtain aqueous phase 1; (2) Take the aqueous phase 1 prepared in step (1), dilute it 10 times with deionized water, and stir it evenly to obtain aqueous phase 2; (3) Add polylactic acid-glycolic acid copolymer (PLGA) and natural plant essential oil to dichloromethane and stir until completely dissolved to obtain the oil phase; (4) The oil phase prepared in step (3) is slowly added to the aqueous phase 1 in step (1), and a uniform and stable emulsion 1 is formed by ultrasonic treatment; (5) Emulsion 1 is injected into the aqueous phase 2 prepared in step (2) at a constant rate and stirred while being injected to form emulsion 2; Emulsion 2 is placed in the open at room temperature and stirred continuously for 12 hours to allow dichloromethane to fully evaporate and obtain uniformly dispersed essential oil nanoparticles. (6) Add calcium chloride (CaCl2) to deionized water and stir until completely dissolved to obtain aqueous phase 3; (7) Add sodium alginate to deionized water, heat and stir for 12 hours to completely dissolve sodium alginate and form a uniform sodium alginate hydrogel. (8) Pour the sodium alginate hydrogel prepared in step (7) into a pre-set spherical mold, and use a syringe to uniformly inject the essential oil nanoparticles prepared in step (5) into the interior of the hydrogel in the mold; then immerse the mold containing the essential oil nanoparticle hydrogel into the aqueous phase 3 of step (6), and after standing to complete the initial curing, demold to obtain a spherical sodium alginate blank containing essential oil nanoparticles; continue to place the blank in the aqueous phase 3 for a period of time to cure, and take it out after curing to obtain the sodium alginate aromatic decompression ball containing essential oil nanoparticles.

3. The preparation method according to claim 2, characterized in that, The mass fraction of PVA in aqueous phase 1 in step (1) is 1.5-3%.

4. The preparation method according to claim 2, characterized in that, The heating temperature in step (1) is 70-100℃, and the stirring speed is 150-600rpm.

5. The preparation method according to claim 2, characterized in that, The mass fraction of PVA in aqueous phase 2 in step (2) is 0.15-0.3%.

6. The preparation method according to claim 2, characterized in that, The molar ratio of PLGA to essential oil in step (3) is 1:0.1-0.

5.

7. The preparation method according to claim 2, characterized in that, The mass fraction of PLGA in the oil phase in step (3) is 0.5-2%.

8. The preparation method according to claim 2, characterized in that, The ultrasonic treatment in step (4) has a power of 150-300W and an ultrasonic time of 5-10min.

9. The preparation method according to claim 2, characterized in that, The volume ratio of emulsion 1 to aqueous phase 2 in step (5) is 1:3-5.

10. The preparation method according to claim 2, characterized in that, In step (5), the rate at which emulsion 1 is injected into aqueous phase 2 is 0.5-1 mL / min.

11. The preparation method according to claim 2, characterized in that, The stirring rate of emulsion 2 in step (5) is 800-1500 rpm.

12. The preparation method according to claim 2, characterized in that, The mass fraction of CaCl2 in aqueous phase 3 in step (6) is 4-5%.

13. The preparation method according to claim 2, characterized in that, The heating temperature in step (7) is 40-60℃.

14. The preparation method according to claim 2, characterized in that, The mass fraction of sodium alginate in sodium alginate hydrogel in step (7) is 2.5-3%.

15. The preparation method according to claim 2, characterized in that, The total curing time of the spherical sodium alginate preform containing essential oil nanoparticles in step (8) in aqueous phase 3, taking a spherical preform with a diameter of 5cm as an example, is not less than 12 hours.

Images