Arjuna

Terminalia arjuna, typically called arjuna, belongs to the household of Combretaceae. Its bark decoction is being utilized in the Indian subcontinent for anginal pain, hypertension, heart disease, and dyslipidemia, based upon the observations of ancient physicians for centuries.It is an ayurvedic remedy that has actually been pointed out because vedic period in numerous ancient Indian medical texts consisting of Charaka Samhita, Sushruta Samhita, and Astang Hridayam. [1]

History

According to the Mahabharata – among the most respected books of Indian mythology – Arjuna was one of five brothers and a central character in this ancient Indian epic. Son of the god Indra and renowned for his skill in archery, he was understood for his steadfastness and single mindedness in pursuing his goals. His commitment to Lord Krishna earned him the divine understanding of the Bhagavad-Gita and the character of Arjuna symbolizes purity, integrity, loyalty and valour. It is stated that the hero of this legendary was named after the Terminalia Arjuna tree because of its protective impacts. The Arjuna herb was understood for its function in protecting vitality and was nicknamed “Guardian of the Heart”, displaying similar qualities to the hero of the Indian legend. In Sanskrit the word Arjuna indicates “shining”, mentioning the silvery glittering quality of the outer bark of the tree. Once a year this bark peels away to expose the inner red healing bark, making it accessible for harvest without harm to the tree. [2]

Description

Arjuna grows to about 20– 25 metres tall; typically has actually a strengthened trunk, and forms a large canopy at the crown, from which branches drop downwards. It has oblong, cone-shaped leaves which are green on the top and brown below; smooth, grey bark; it has pale yellow flowers which appear between March and June; its glabrous, 2.5 to 5 cm fibrous woody fruit, divided into five wings, appears between September and November. The tree does not suffer from any significant illness or pests, however it is prone to Phyllactinia terminale and rot due to polystictus affinis.

Distribution and environment

The arjuna is seen throughout the Indian Subcontinent, and normally discovered growing on river banks or near dry river beds in Uttar Pradesh, Bihar, Maharashtra, Madhya Pradesh, West Bengal, Odisha and south and main India, along with Sri Lanka and Bangladesh. It has actually also been planted in Malaysia, Indonesia and Kenya. [3]

Category

• Kingdom: Plantae
• Department: Magnoliophyta
• Class: Magnoliopsida
• Order: Myrtales
• Household: Combretaceae
• Genus: Terminalia
• Species: T. arjuna
• Zoological name: Terminalia arjuna

Other names: Arjuna, Koha, Kahu, Arjan, White Marudah, White Murdh, Arjuna Myrobalan, Orjun, Yerra maddi, Sadada, Sadaru and a lot more. [4]

Attributes of the Arjuna Tree

Arjuna, also referred to as arjun, is a stunning, deciduous tree that can reach heights up to 100 feet and has been valued for its wood and therapeutic homes for generations. It grows throughout the damp, marshy, sub-Himalayan areas of India and Sri Lanka, producing clusters of small white or yellow flowers amidst its cone-shaped leaves. The most popular part of the tree is its red inner bark, which is appreciated as a tonic for the heart and is considered similar to hawthorn in European herbalism. The thick, white-to-pinkish-gray outer bark molts naturally once a year and is gathered when the trees are mature. Offering the tree time to recover and regrow its bark is a crucial part to sustainable harvesting. Centuries back, the arjuna tree was offered a name befitting its conventional role of safeguarding the heart, similar to its mythological name brought fortitude, strength, and security to his family in battle.The term “arjuna” means “intense,” “white,” or “shining” in Sanskrit, just like the light-reflective bark of the arjuna tree.

Phytochemistry

The major constituents of T. arjuna in stem bark, root bark, fruits, leaves and seeds are well defined. The preliminary phytochemical analysis of existing substances in T. arjuna was carried out according to different standard procedures. As bark was considered to be the most important constituent from the medical point of view, initially reported that the bark had 34% ash content consisting completely of pure calcium carbonate. Liquid extract of T. arjuna is reported to have 23% calcium salts and 16% tannins. Organic extracts of T. arjuna bark were also prepared using the sequential methods with a number of organic solvents such as hexane, benzene, chloroform, acetone, dichloromethane, ethyl acetate, butanol, ethanol, methanol and ether, and so on, to extract various phytochemical constituents. The chemical structures of available substances were verified by numerous innovative methods like HPLC, UPLC, LC-ESI-MS/MS analysis.26, 27, 55, 56 Polyphenols, flavonoids, tannins, triterpenoids, saponins, sterols and minerals are the significant constituents of T. arjuna. Such amino acids like tryptophan, tyrosine, histidine and cysteine are likewise the main ingredients in T. arjuna. [5]

Nutrient

5 bark powder samples of Arjuna (Terminalia arjuna) having different origins consisting of 2 business brand names were analyzed for 8 minor (Al, Na, K, Mg, Ca, P, Cl, Fe) and 19 trace (As, Bachelor’s Degree, Br, Co, Cr, Cs, Cu, Eu, Hg, La, Mn, Rb, Sb, Sc, Sm, Sr, Th, V, Zn) components by INAA. Likewise concentrations of Ni, Cd and Pb were determined by AAS and of Sn by ICP-MS. Arjuna bark powder is enriched in Ca, Mg, K Cl and Fe with considerable quantities of Mn and A number of hazardous components such as As, Hg and Pb were likewise discovered. [6]

Microscopy

Transverse section of fresh bark reveals cork composed of consistently organized a number of layers of small, tangentially elongated cells. Below cork is an area of cortex, made up of thin-walled, more or less brick-shaped parenchymatous cells containing cluster crystals of calcium oxalate. A few groups of sclerenchymatous pericyclic fibers are spread in the cortex. Secondary phloem includes phloem parenchyma made up of thin-walled, polygonal cells with wavy walls including cluster crystals of calcium oxalate and pigmented cells. Phloem fibers, made up of sclerenchymatous cells, occur in groups and are spread in the form of spots in parenchyma. Narrow and nearly straight medullary rays are also present. [7]

Prospective benefits

There’s restricted research on arjunarishta, and the majority of it was conducted in animals. For that reason, no definitive conclusions can be made about its effectiveness in human beings.

High in anti-oxidants

Anti-oxidants are compounds that reduce the effects of extremely unstable molecules called complimentary radicals. Free extreme damage is connected to chronic conditions like cardiovascular disease, type 2 diabetes, and cancer. Lots of ingredients in arjunarishta, such as T. arjuna, V. vinifera, and W. fruticosa, consist of substances that work as anti-oxidants, including flavonoids, triterpenoids, glycosides, and phenolic acids.In test-tube and animal studies, T. arjuna, V. vinifera, and W. fruticosa anti-oxidants have actually been revealed to reduce the development and spread of cancers in the stomach, liver.However, it’s unclear whether taking arjunarishta would produce similar results, as these research studies were conducted using concentrated extracts. It’s also unclear whether these benefits would apply to humans.

Might aid blood sugar control

Animal research suggests that arjunarishta and its active ingredients might lower blood glucose levels.In a mouse study, researchers found that both arjunarishta and T. arjuna extract decreased fasting blood sugar levels significantly more than a control.Similarly, a research study in rats with diabetes discovered that treatment with a T. arjuna extract for 15 days considerably lowered and stabilized fasting blood glucose levels.Additional studies in mice with diabetes have also discovered the mixture’s components to substantially decrease fasting blood glucose levels.However, arjunarishta consists of jaggery– an unrefined sugar item. As such, while the majority of the components might help blood sugar level control in animal research studies, arjunarishta as a whole may disagree for individuals with diabetes.Human research studies on arjunarishta’s impacts on blood sugar level management are needed before suggesting it for this purpose.

Other prospective benefits

Arjunarishta and its active ingredients have been associated with other possible advantages, consisting of:.

May minimize cancer threat. Animal and test-tube research studies recommend that particular ingredients in arjunarishta may have anticancer properties. Still, human studies are needed in this area.May have anti-asthmatic homes. Animal research suggests that a few of the blend’s active ingredients might have anti-asthmatic homes and help reduce lung inflammation. Once again, human research studies are needed.May help aerobic exercise efficiency. A study in 30 healthy young adults found that T. arjuna, a key active ingredient in arjunarishta, enhanced aerobic workout endurance. [8]

Benefits of Arjun Fruit

Eliminates halitosis

Foul breath is among the most common way of life issues that accompany many individuals. You would not want to go to your work location having foul breath. Consuming arjun fruit can in fact enhance your mouth smell and can have advantages connected to oral health. This fruit has substances that have healing residential or commercial properties that can even aid your gum issues and bleeding from the teeth. You can in fact have arjun fruit as soon as every morning to begin your day with a fresh mouth.

Makes Bones Stronger

If you are struggling with any kind of bone issues, specifically that damages our bones, then it can be really effective for you to eat arjun fruit. In the old age, individuals might feel this bone issues growing in time. Bones of older grownups tend to end up being weaker which is when you can actually take complete advantages of arjun fruit. You can eat it raw of make a juice out of it. It may even assist you with bone conditions like osteoporosis and arthritis. It may not be able to treat it however can reduce its symptoms.

Lowers Teeth and Gum Issues

Oral health plays an extremely crucial role in identifying the way of life, self-confidence and some other elements. Eating arjun fruit can really help you decrease your gum issues and improve teeth health. Here are some typical oral problems that could be solved by consuming arjun fruit in your diet plan-.

• Bleeding from the teeth
• Reduces cavities
• Toothache
• Discomfort in gums
• Bleeding gums

You can have this fruit in the form of juice, or raw. You can likewise consume arjun fruit powder and put it in the form of a paste on the area where you are facing gum or teeth problems. Nevertheless, it is better to consult a doctor initially and take arjun fruit more as a solution than a treatment.

4. Enhances Heart Rate Rhythms

It has been observed that eating arjun fruit regularly in your diet plan can minimize the threat of heart rhythm disorder. This fruit can help to maintain typical heart rate rhythm that might reduce the threat of cardiac arrest. You can likewise have arjun bark powder and mix it in a glass of water with some honey to cleanse your blood. Arjun fruit thus could be beneficial to improve heart health too. [9]

Extract preparation

The sun dried bark of T. arjuna was given the laboratory and powdered and drawn out in water (1:8, after travelling through 80 mesh size) by boiling (4 h). The extracts were consequently filtered through muslin cloth and the filtrate was spray dried. For preparation of water service of T. arjuna extracts, dried powder (500 mg), was liquified in pure water and after that centrifuged (500g, 15 minutes). The supernatants were moved to micro-centrifuge tubes and stored (at − 20 ° C). The quantity of overall soluble solids in supernatant was measured using gravimetric analysis which functioned as the basis to create T. arjuna concentrations. [10]

Method of Preparation Of Arjunarishta

The main ingredient arjuna is washed and sun-dried. It is then powdered and sieved to remove pollutants and solid particles.Separately, the aromatic herbs i.e. madhuka, dhataki and draksha are cleaned, dried, powdered, sieved and kept aside. The powdered arjuna bark is then immersed in a particular quantity of water and permitted to soak over night. In the morning, the preparation is then boiled and decreased to 1/4 amount and gone through a muslin cloth to remove impurities. Include jaggery to the clear decoction, stir it effectively and filter to remove solid particles. Now, pour the decoction in a wide-mouthed vessel, add the powdered aromatic herbs to the filtrate and seal the opening of the container.Keep it aside in the fermentation space and enable it to ferment. Keep a check on the fermentation process. When the fermentation is done, filter the fermented liquid through a muslin cloth to remove solid particles and pollutants. The concoction is then poured in air-tight containers, stored in a cool, dry place and kept for maturation. [11]

What can I use it for?

Arjuna bark affects an increase in levels of superoxide dismutase, catalase and glutathione levels. This action provides protection against oxidative tension, with a particular affinity for heart tissue. Arjuna likewise shows a positive inotropic action upon heart muscle, stabilizing any irregular contractions and promoting a healthy blood pressure. Arjuna mediates the inhibition of cholesterol biosynthesis within the liver, improving cholesterol metabolic process and also encouraging basic hepatic cellular regeneration. Arjuna has demonstrated anti-bacterial, anti-viral and anti-mutagenic activity against particular strains such as salmonella, E.coli and HIV. In addition, it has actually likewise shown the ability to recover damaged and wounded skin cells, and prevent the development of tumours.

Into the heart of arjuna

Arjuna is first and primary a cardio tonic. Arjuna is specifically suggested for all heart based conditions, strengthening, nourishing and fixing heart and capillary tissue. It will influence a reduction in any swelling and congestion that might be impairing heart function but likewise support any psychological tension and anxiety impacting the organ.The regenerative impact that this herb has on the liver, also makes it incredibly rejuvenative to the liver as an organ, enhancing total efficiency and metabolism, with the added capability of improving cholesterol metabolic process. Arjuna healing procedure with a particular focus upon damaged skin and bones and damage triggered by chronic viral and bacterial infection. Arjuna is particularly indicated in angina, congestive heart failure, cardiac arrhythmia, and high blood pressure. All have actually showed signs of enhancing in human clinical trials. It has also been shown to lower human overall cholesterol and triglyceride levels. It minimizes swelling and congestion that can harm the heart. It can be used to deal with emotional disruption and ‘broken heart’. It reinforces the muscles of the heart as well as toning the capillaries and enhancing versatility which helps to prevent high blood pressure. It helps to balance the movement of vyana vayu in the heart and regulate blood circulation. Arjuna’s affinity for the chest directs it to the lungs and to relieve efficient coughs with generous mucous in bronchitis and asthma. It can also deal with haemoptysis affected by increased heat and inflammation. Arjuna improves liver function and inflammation, making it extremely showed in cirrrosis. Arjuna is useful as an alterative for clearing the skin of swelling typical in acne, acne rosacea, pruritus and urticarial.The wound recovery capability of arjuna is demonstrated in post-trauma healing of scars, post-operative recovery and fixing fractures. It can likewise be utilized internally and externally for healing diabetic ulcers.The astringency of arjuna prevents premature ejaculation and uterine bleeding. [12]

How to Take Arjuna

If arjuna’s heart-nourishing powers and wide variety of other benefits are calling your name, there are several ways to include this herb into your routine. To figure out the way that is finest method for you, just tune into any particular intents and trust where your heart is called. And naturally, if you are dealing with a more complicated health condition, we recommend working with an Ayurvedic specialist for particular and personalized assistance. By itself. Arjuna can be utilized on its own for those who prefer working with a single herb. The most conventional approach for taking arjuna is the powder; try drinking it in warm water as a tea. Or try the liquid extract for a quickly, practical option.In a supplement. Arjuna is included in much of Banyan’s supplements, consisting of Heart Formula, Stress Ease, Women’s Natural Transition, Healthy Bones, and Sugary Food Ease. Topically. Arjuna is a perfect ingredient for our soothing and soothing organic oils and balms. It can be found in Mahanarayan Oil, Daily Massage Oil, and Breast Care Balm.

Is Arjuna Safe?

Arjuna is generally thought about safe in most circumstances, making it a prepared ally for many. That said, it’s constantly essential to approach the use of herbs with care. [13]

Dosage

What is the advised dosage of arjuna?

Based on clinical research study done on the arjuna plant up until now, the following does have actually been suggested.

For chest discomfort: 500mg of the powdered bark of the arjuna plant is recommended to be taken three times daily, together with the conventional treatment for angina for about 3 months.

For cardiac arrest: 500 mg of powdered arjuna bark can be taken three times per day along with the standard treatment for cardiac arrest for about 2 weeks. [14]

Directions

1. Arjuna bark being the main ingredient is to start with washed and left for drying in the sun.
2. It is then processed to get the final product in a powdered type. Do remember to sieve the powder as soon as to eliminate the impurities or any strong particles.
3. The other herbs (madhuka, dhataki and draksha) which are utilized will likewise be cleaned thoroughly and sun dried.
4. These herbs are also processed to form powder. Keep all the herbs individually and sieve them as soon as to clear the possibilities of solid impure particles.
5. The powdered arjuna bark is then left in water for the soaking treatment for at least 24 hr.
6. The soaked item is then boiled until the amount is decreased to less than half. To get rid of the additional possibilities of impurities, pass it through muslin fabric.
7. Now add jaggery or gud to the preparation and stir it properly.
8. Add all the herbs and seal the container tightly.
9. Enable the decoction to ferment appropriately.
10. When the fermentation is done, filter it again utilizing muslin cloth to further purify.
11. It is ready to use and can be kept in airtight containers. [15]

Arjuna bark for skin

The bark of Arjuna is used to cure different skin associated problems. It has antioxidant, anti-inflammatory and antimicrobial residential or commercial properties that assist in eliminating skin issues.

In Ayurveda, the Arjuna tree has actually been referred to as a gold mine of medical homes. Arjuna tree, fruits, leaves and roots are used in Ayurveda for the treatment of numerous illness. Let us tell you that the bark of Arjuna is used to remove numerous types of skin associated problems. It has antioxidant, anti-inflammatory and antimicrobial residential or commercial properties that help in removing skin problems. In today’s short article, we will tell you which skin problems are gotten rid of by the powder of Arjun bark–.

Dry skin

Arjun bark is an efficient medicine for those with dry skin. Its extract helps in maintaining moisture in the skin. Together with this, it increases the production of sebum in the skin. Applying a face pack made of Arjun bark on the face eliminates the issue of dry skin and makes the face radiance.

Fine Lines and Wrinkles

Applying arjuna bark on the face helps in avoiding the indications of aging. It has rich anti-oxidant residential or commercial properties that protect the skin from damage brought on by free radicals. Using the bark of Arjuna on the skin tightens up the skin and removes the problem of fine lines and wrinkles.

Itching

Arjuna bark has anti-inflammatory properties, which gets rid of the issue of swelling and inflammation on the skin. Apart from this, making use of arjuna bark is also helpful in the issue of pimples and itching on the face. It cools the skin and gets rid of the problem of itching.

Pimples

Arjun bark face pack is likewise an efficient home remedy in the issue of acne. It has antimicrobial properties that eliminate the problem of acne and pimples on the skin. This.

Stains

Arjun bark face pack is very efficient for people who have the problem of acnes on the face. Using it on the face removes the problem of acne. Along with this, the bark of Arjuna is likewise beneficial to get rid of the dark areas and tanning of the face.

How to make Arjuna bark face pack

1. To make a face pack of Arjuna bark, take the powder of the bark of this tree.
2. Now add a spoonful of raw milk or honey to it.
3. Now apply this paste on the afflicted location of your skin.
4. After this wash off with clean water after 15-20 minutes [16]

Interactions with Organ Systems

Stomach

The methanolic extract of Arjuna appears to protect stomach tissue from lipopolysaccharide (LPS) from Heliobactor Pylori, which is understood to induce ulcers. [57] This protective result has been noted versus alcohol (7 day preload), Dexamethasone (10 day preload), and diclofenac sodium (single dose) where 100-200mg/ kg of an 80% ethanolic extract gave outright defense versus ulcer formation from Dexamethasone and alcohol, while 400mg/kg of an acute dosage gave outright security against Diclofenac Sodium. [58] The favorable control in this study, Rantidine (35mg/kg Diclofenac, 50mg/kg alcohol, 4mg/kg Dexamethasone) likewise conferred outright protection, [58] and these protective results against Diclofenac have actually been duplicated with a methanolic extract and believed to be related to the anti-oxidative capacity.

Ears

One study noted that Arjuna extracts, specifically acetonic extraction, was able to cause death of Staphylococcus aureus germs and reached Escherchia Coli, Acinetobacter sp, Proteus mirabilis, and Candida albicans; [60] the authors assumed that the outcomes suggest that Arjuna might work versus ear infections (although undoubtedly initial).

Liver

In isolated hepatocytes (HepG2), 5-100mcg/ mL of the water extract of Arjuna is able to concentration dependently minimize the biomarkers of oxidation caused by TERT (pro-oxidative agent), with totally free radicals (ROS) and lipid peroxidation (TBARS) being lowered as much as 69% and 62% respectively. [61] The reduction of antioxidant enzymes by TERT was also significantly attenuated up to 60% (SOD), 82% (Catalase), and Glutathione enzymes (62-65% for peroxidase and reductase; totally avoiding any decrease in Glutathione S-transferase). [61] These antioxidant results are believed to underlie results accomplished with 50mg/kg water extract of Arjuna for 7 days prior to CCL4 caused hepatotoxicity, where Arjuna considerably prevented the rise in GPT (dosage dependent decreases up to 50mg/kg, no included advantage at 100mg/kg), stabilized ALP, and increased hepatic levels of antioxidant levels either to control levels (Catalase and Glutathione S-Transferase) or above control (SOD), a potency similar to Vitamin C at the exact same oral doses.

Kidneys

250-500mg/ kg of a hydroalcoholic extract of Arjuna bark (not an oral study, however the comparable injected into perfused kidneys) appears to lower oxidation and concomitantly increase antioxidant enzymes (Catalase and Glutathione. A preservation of anti-oxidant enzymes in reaction to CCL4 is observed to be of similar effectiveness to Vitamin C and has noted protective results in the kidneys of Alloxan-induced diabetic rats at oral doses of 250-500mg/ kg of the water extract.

Molecules that are discovered in Arjuna that have been kept in mind to exert protective impacts on kidney cells include Casuarinin, a tannin structure, with more potency than the water soluble type of Vitamin E referred to as Trolox.

Urinary System

In vitro, Arjuna seems able to reduce development rates of calcium-based kidney stones (calcium oxalate and calcium phosphate checked) with the butanol extract being most effective.

Testicles

One study using arsenic-induced testicular damage in rats kept in mind that 4 days pretreatment with separated Arjunolic acid can prevent oxidative testicular damange and histological changes in reaction to arsenic. This study noted that, in vitro, the antioxidant potential of Arjunolic Acid peaked at a focused of 0.4 mg/mL and this appeared to correlated with an oral consumption of 20mg/kg (as 50mg/kg did not confer extra protective advantages) which the overall protective advantage was near outright, and sligtly less reliable than 100mg/kg Vitamin C. [17]

Precautions:

During Pregnancy and Breastfeeding: There is no evidence that Terminalia Arjuna is perhaps hazardous during pregnancy & & breastfeeding. Please stay on the safe side and prevent using it during pregnancy.

Bleeding Conditions: It might slow blood clot and risk bleeding and bruising in individuals with bleeding conditions.

Surgical treatment: Terminalia might interfere with blood glucose control and increase the threat of bleeding during surgical treatment. So stop utilizing it before 2 weeks before an arranged surgery.

Storage:

Two years if sealed and save away from direct sunshine. [18]

Conclusion

The everlasting interest in medicinal plants has actually caused the discovery of new chemical constituents and pharmacological actions of arjuna. Its efficacy as an anti-ischemic agent, a potent antioxidant, and an antiatherogenic representative has been amply demonstrated in various speculative and medical studies. Nevertheless, significant lacunae of these research studies include the absence of phytochemical standardization of the extract, bioavailability studies, and properly designed research studies to examine its long-lasting toxicity results. Its specific function in primary/secondary coronary avoidance requires to be investigated. In addition to this, studies to try to find the impact of arjuna on CYP450 enzymes and its interactions with other drugs like statin, aspirin, angiotensin-converting enzyme (ACE) inhibitors, and β-blocker need to be developed. Increasing the awareness regarding its medical use can provide a direction to the doctors to react to the difficulties in dealing with heart diseases. [19]

References

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4220499/
2. https://www.indigo-herbs.co.uk/natural-health-guide/benefits/arjuna
3. https://en.wikipedia.org/wiki/Terminalia_arjuna
4. http://www.ecoindia.com/flora/trees/arjun-tree.html
5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5198828/
6. https://www.researchgate.net/publication/320634680_INAA_of_essential_micronutrients_in_Terminalia_arjuna_bark_powder_a_versatile_heart_tonic
7. https://www.pharmacy180.com/article/arjuna-317/
8. https://www.healthline.com/nutrition/arjunarishta
9. https://www.sciencedirect.com/science/article/pii/S1110863013000888
10. https://www.onlymyhealth.com/arjun-fruit-benefits-1652761281
11. https://www.netmeds.com/health-library/post/arjunarishta-benefits-uses-ingredients-method-dosage-and-side-effects
12. https://www.herbalreality.com/herb/arjuna/
13. https://www.banyanbotanicals.com/info/plants/ayurvedic-herbs/arjuna-benefits/
14. https://aiwo.com/blogs/blog/terminalia-arjuna-benefits-sources-and-side-effects
15. https://wellversed.in/blogs/articles/what-is-arjunarishta-all-you-need-to-know
16. https://hindustannewshub.com/beauty-tips/these-5-skin-problems-are-removed-by-the-bark-of-arjuna-know-how-to-make-its-face-pack/
17. https://examine.com/supplements/terminalia-arjuna/research
18. https://chiltanpure.com/product/arjuna-powder/
19. https://www.sciencedirect.com/science/article/pii/S222541101630236X