
This study evaluated the color stability, bioactive compounds, and antioxidant activity of roselle calyx powders dissolved at different pHs. The results showed that purple roselle calyx powders revealed better color than red roselle, and foam-mat dried powders were better than the conventionally dried powder. The best solution without pH adjustment was found in foam-mat dried purple calyces. pH values significantly affected color stability and quality, bioactive compounds, and antioxidant activity of roselle powder solutions. The lightness, redness, and yellowness of the solutions at different pH values ranged from 27.00 to 74.45, from 0.70 to 52.20, and from 3.9 to 47.50, respectively. The non-adjusted pH solution had a lightness of 33.80–49.05, redness of 19.15–42.45, and yellowness of 7.10–18.35. The color quality, indicated by color intensity at different pHs, ranged from 0.03 to 15.24; the non-adjusted pH solution had a color intensity of 1.37–33.48, revealing that pH decreased color quality. Retention of phenolics and flavonoids was 8.02%–99.69% and 0.00%–81.05%, respectively, indicating the instability of bioactive compounds. Roselle antioxidant activity was observed at different pHs, ranging from 0.00 to 1.11 mg Trolox equivalent (TE)/g for DPPH (2, 2-diphenyl-1-picrylhydrazyl) scavenging activity and 0.46–104.16 mg TE/g for the ABTS [2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] assay. Acidic pHs preserved better all dependent parameters. In practice, the pH value should be considered when using roselle calyx powders in food products. This study used a solution as a model for a watery food system. Suitable products to use roselle calyx powders are water-based products with an acidic pH, such as syrups, yogurts and yogurt-based products, fermented milk, and sour-taste beverages. Roselle calyx powders are suitable to use as coloring agents or as bioactive compounds to provide healthy functional properties. The use of foam-mat dried powders is suggested due to the better antioxidant activity and color preservation than conventionally dried powder.
Citation: Teti Estiasih, Jatmiko Eko Witoyo, Khofifah Putri Wulandari, Fadhillah Dwi Juniati, Widiastuti Setyaningsih, Hanifah Nuryani Lioe, Miguel Palma, Kgs Ahmadi, Hamidie Ronald Daniel Ray, Elya Mufidah. Stability comparison of conventional and foam-mat red and purple dried roselle calyces powder as a function of pH[J]. AIMS Agriculture and Food, 2025, 10(1): 177-198. doi: 10.3934/agrfood.2025010
[1] | Shima Nazari, Pouya Farokhnezhad Afshar, Leila Sadeghmoghadam, Alireza Namazi Shabestari, Akram Farhadi . Developing the perceived social support scale for older adults: A mixed-method study. AIMS Public Health, 2020, 7(1): 66-80. doi: 10.3934/publichealth.2020007 |
[2] | Linna Tam-Seto, Patricia Weir, Shilpa Dogra . Factors Influencing Sedentary Behaviour in Older Adults: An Ecological Approach. AIMS Public Health, 2016, 3(3): 555-572. doi: 10.3934/publichealth.2016.3.555 |
[3] | Nguyen Xuan Long, Nguyen Bao Ngoc, Tran Thi Phung, Dao Thi Dieu Linh, Ta Nhat Anh, Nguyen Viet Hung, Nguyen Thi Thang, Nguyen Thi Mai Lan, Vu Thu Trang, Nguyen Hiep Thuong, Nguyen Van Hieu, Hoang Van Minh . Coping strategies and social support among caregivers of patients with cancer: a cross-sectional study in Vietnam. AIMS Public Health, 2021, 8(1): 1-14. doi: 10.3934/publichealth.2021001 |
[4] | Anna Kavga, Ioannis Kalemikerakis, Theocharis Konstantinidis, Ioanna Tsatsou, Petros Galanis, Eugenia Karathanasi, Ourania Govina . Factors associated with social support for family members who care for stroke survivors. AIMS Public Health, 2022, 9(1): 142-154. doi: 10.3934/publichealth.2022011 |
[5] | Erin Nolen, Catherine Cubbin, Mackenzie Brewer . The effect of maternal food insecurity transitions on housing insecurity in a population-based sample of mothers of young children. AIMS Public Health, 2022, 9(1): 1-16. doi: 10.3934/publichealth.2022001 |
[6] | Nicola Magnavita, Francesco Marcatto, Igor Meraglia, Giacomo Viti . Relationships between individual attitudes and occupational stress. A cross-sectional study. AIMS Public Health, 2025, 12(2): 557-578. doi: 10.3934/publichealth.2025030 |
[7] | Alexandria Nyembwe, Yihong Zhao, Billy A. Caceres, Kelli Hall, Laura Prescott, Stephanie Potts-Thompson, Morgan T. Morrison, Cindy Crusto, Jacquelyn Y. Taylor . Moderating effect of coping strategies on the association between perceived discrimination and blood pressure outcomes among young Black mothers in the InterGEN study. AIMS Public Health, 2025, 12(1): 217-232. doi: 10.3934/publichealth.2025014 |
[8] | Carlee Bellapigna, Zornitsa Kalibatseva . Psychosocial risk factors associated with social anxiety, depressive and disordered eating symptoms during COVID-19. AIMS Public Health, 2023, 10(1): 18-34. doi: 10.3934/publichealth.2023003 |
[9] | Sandra Racionero-Plaza, Itxaso Tellado, Antonio Aguilera, Mar Prados . Gender violence among youth: an effective program of preventive socialization to address a public health problem. AIMS Public Health, 2021, 8(1): 66-80. doi: 10.3934/publichealth.2021005 |
[10] | Gabriela Štefková, Zuzana Dankulincová Veselská, Viola Vargová, Marek Pal'o . The Association of Education, Employment and Living with a Partner with the Treatment among Patients with Head and Neck Cancer. AIMS Public Health, 2015, 2(1): 1-9. doi: 10.3934/publichealth.2015.1.1 |
This study evaluated the color stability, bioactive compounds, and antioxidant activity of roselle calyx powders dissolved at different pHs. The results showed that purple roselle calyx powders revealed better color than red roselle, and foam-mat dried powders were better than the conventionally dried powder. The best solution without pH adjustment was found in foam-mat dried purple calyces. pH values significantly affected color stability and quality, bioactive compounds, and antioxidant activity of roselle powder solutions. The lightness, redness, and yellowness of the solutions at different pH values ranged from 27.00 to 74.45, from 0.70 to 52.20, and from 3.9 to 47.50, respectively. The non-adjusted pH solution had a lightness of 33.80–49.05, redness of 19.15–42.45, and yellowness of 7.10–18.35. The color quality, indicated by color intensity at different pHs, ranged from 0.03 to 15.24; the non-adjusted pH solution had a color intensity of 1.37–33.48, revealing that pH decreased color quality. Retention of phenolics and flavonoids was 8.02%–99.69% and 0.00%–81.05%, respectively, indicating the instability of bioactive compounds. Roselle antioxidant activity was observed at different pHs, ranging from 0.00 to 1.11 mg Trolox equivalent (TE)/g for DPPH (2, 2-diphenyl-1-picrylhydrazyl) scavenging activity and 0.46–104.16 mg TE/g for the ABTS [2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] assay. Acidic pHs preserved better all dependent parameters. In practice, the pH value should be considered when using roselle calyx powders in food products. This study used a solution as a model for a watery food system. Suitable products to use roselle calyx powders are water-based products with an acidic pH, such as syrups, yogurts and yogurt-based products, fermented milk, and sour-taste beverages. Roselle calyx powders are suitable to use as coloring agents or as bioactive compounds to provide healthy functional properties. The use of foam-mat dried powders is suggested due to the better antioxidant activity and color preservation than conventionally dried powder.
In December 2019, the world is facing the emergence of a new pandemic, which is called coronavirus disease 2019 (COVID-19). Then, COVID-19 spreads to world widely over the first two months in 2020. There were 492,510 confirmed cases of COVID-19 infection and 22,185 dead cases in world [1], [2]. Therefore, it poses a continuing threat to human health because of its high transmission efficiency and serious infection consequences as well, it transmits by direct contact. Many researchers have tried to study and understand the dynamical behavior of COVID-19 through the transmission dynamics and calculate the basic reproduction number of COVID-19. It has become a key quantity to determine the spread of epidemics and control it. For example, in [3], Li et al. conducted a study of the first 425 confirmed cases in Wuhan, China, showing that the reproduction number of COVID-19 was 2.2, and revealed that person to person transmission occurred between close contacts. Other research [4] shows that the reproduction number of COVID-19 becomes 2.90, which is being increasing. In [5], Riou et al. studied pattern of early human to human transmission of COVID-19 in Wuhan, China. In [6], Hellewell et al. investigated the feasibility of controlling 2019-nCoV outbreaks by isolation of cases and contacts. Chen et al.[7], suggested mathematical model for simulation the phase-based transmissibility of novel coronavirus. Bentout et al. [8] developed an susceptible exposed infectious recovered model to estimation and prediction for COVID-19 in Algeria. Belgaid et al.[9] suggested and analysis of a model for Coronavirus spread. Owolabi et al. [10] proposed and analyzed a nonlinear epidemiological model for SARS CoV-2 virus with quarantine class. Flaxman et al. [11] suggested and estimating the effects of non-pharmaceutical interventions on COVID-19 in Europe. Kennedy et al. [12] suggested a mathematical model involving the effects of intervention strategies on COVID-19 transmission dynamics. Feng et al. [13] studied a COVID-19 model with the effects of media and quarantine in UK. In this present study, we will show effects of the quarantine strategy and media reports on the spread of COVID-19.
We propose a mathematical model for COVID-19 transmission dynamics with the quarantine strategy and media effects. We start the model formulation by denoting the total size of the population by N which is classified further into five classes, the susceptible S(t), the exposed E(t), the infected I(t), the hospital quarantined Q(t) and the recovery R(t) at any time t, So,
And the corresponding dynamical model has formulated through the nonlinear differential equations as follows,
with initial conditions
In model (1), the birth rate A is taken into susceptible class and natural death rate of population is given by the parameter d. The susceptible will be infected through sufficient direct contacts with infected people in the absence of media alerts by
It is easy see that the 4th and 5th equations are a linear differential equation with respect to variables I(t) and R(t), which are not appear in the other equations of model (1). Hence model (1) can be reduced to the following model:
In this paper, we will discuss the dynamics of model (3) with initial conditions
This paper is organized as follows. In section 2, we will build the basic properties of model such as (positivity, boundedness of solutions and basic reproduction number). Existence of equilibrium points is presented in section 3. In section, the phenomenon of backward bifurcation is considered. The local and global stability of equilibrium points are studied in sections 4. In section 5, numerical simulation results are given. We conclude this paper with a brief conclusion.
On the positivity of solutions for model (3), we have the following result.
Theorem 2.1 Every solution of (3) with initial values (4) is positive as t > 0.
Proof. Let
which can be written as
thus,
so that
Similarly, it can be shown that E(t) > 0 and I(t) > 0 for all time t > 0. Hence all solutions of the model (3) remain positive for all non-negative initial conditions, as required.
Theorem 2.2 All solutions of model (1) which initiate in
Proof. Define the function
Now, it is easy to verify that the solution of the above linear differential inequalities can be written as
where
and
It is easy to see that model (3) always has a disease-free equilibrium
Consequently, from Theorem 2 of [14], we have the following result.
Theorem 2.3 The disease-free equilibrium
The basic reproduction number for COVID-19 infection
In this section, we consider the number of equilibrium solutions the model (3). To do so, let
here
Since we assume
where
From (15), we can find that
Cases | D1 | D2 | D3 | D4 | D5 | R0 | Number of sign changes | Number of possible positive real roots |
1 | − | + | + | + | + | ℛ0 > 1 | 1 | 1 |
− | + | + | + | − | ℛ0 < 1 | 2 | 0,2 | |
2 | − | + | + | − | + | ℛ0 > 1 | 3 | 1,3 |
− | + | + | − | − | ℛ0 < 1 | 2 | 0,2 | |
3 | − | + | − | + | + | ℛ0 > 1 | 3 | 1,3 |
− | + | − | + | − | ℛ0 < 1 | 4 | 0,2,4 | |
4 | − | + | − | − | + | ℛ0 > 1 | 3 | 1,3 |
− | + | − | − | − | ℛ0 < 1 | 2 | 0,2 | |
5 | − | − | + | + | + | ℛ0 > 1 | 1 | 1 |
− | − | + | + | − | ℛ0 < 1 | 2 | 0,2 | |
6 | − | − | + | − | + | ℛ0 > 1 | 3 | 1,3 |
− | − | + | − | − | ℛ0 < 1 | 2 | 0,2 | |
7 | − | − | − | + | + | ℛ0 > 1 | 1 | 1 |
− | − | − | + | − | ℛ0 < 1 | 2 | 0,2 | |
8 | − | − | − | − | + | ℛ0 > 1 | 1 | 1 |
− | − | − | − | − | ℛ0 < 1 | 0 | 0 |
Theorem 3.1 The model (3)
(i) has a unique endemic equilibrium if
(ii) could have more than one endemic equilibrium if
(iii) could have 2 or more endemic equilibria if
From the 4th and 5th equations of model (1) we can determent the values of Q* and R* through
The existence of multiple endemic equilibria when
Theorem 3.2 The model (3) exhibits backward bifurcation whenever
Proof. To prove existence of backward bifurcation in the model (3) the Center Manifold approach as outlined by Castillo-Chavez and Song in [17] is used.
Firstly, for clarity and understanding of the Center Manifold Theory the model (3) variables are transformed as follows
Now let
With
It is easy to obtain the right eigenvectors of this Jacobian matrix as
First the non-vanishing partial derivatives of the transformed model (17) evaluated at COVID-19 free equilibrium are obtained as
so that
The sign of the bifurcation parameter b is associated with the following non-vanishing partial derivatives of F(X), also evaluated at the disease free equilibrium
The bifurcation coefficient b is obtained as
Obviously, b is always positive. From Theorem 3.2 the system (17) will exhibit backward bifurcation phenomena if the bifurcation coefficient a is positive. The positivity of a in (22) gives the condition for backward bifurcation, which leads to
In this section, the stability analysis of the all equilibrium points of model (3) studied as shown in the following theorems by used some criterion.
Theorem 4.1 The COVID-19 equilibrium point P* of the model (3) is locally asymptotically if the following conditions are hold
Proof. The Jacobian matrix of model (3) at
here
clearly, the characteristics equation of J(P*) is given by
where
furthermore, we have that
Now, according to Routh-huewitz criterion P* will be locally asymptotically stable provided that
The purpose of this section is to investigate the global stability by using Lyapunov function for COVID-19 free equilibrium point and COVID-19 equilibrium point respectively. We obtain the result in the following theorems
Theorem 4.2 The disease-free equilibrium
Proof. Consider the following function
clearly,
now, by doing some algebraic manipulation and using the condition (33), we get
Obviously,
Theorem 4.3 P* in case i of Th. (3.1) is globally asymptotically stable if
Proof. At the COVID-19 equilibrium point
By above equations (4.4) and assumptions
we obtian
now, define the Lyapunov function
clearly, by derivative of
Since the arithmetical mean is greater than, or equal to the geometrical mean, then
For the parameters values of model (1.1), we can chosen the parameters values from real data available sense Feb. 24 2020 to Apr. 5 2020. The total population of the Iraq for the year 2020 is approximately 40 × 106
Parameter | Definition | Value | Source |
A | Birth rate | 1541.8 | [19] |
β1 | Transmission contact rate between S and I | 0.5 | Estimated |
c | Fraction constant | [0–1] | Estimated |
β2 | Awareness rate | 0.1 | Estimated |
m | Half saturation of media constant | 70 | Estimated |
d | Natural death rate | 3.854510−5 | [19],[20] |
k | Fraction denoting the level of exogenous re-infection | 0.05 | Estimated |
ϵ | Quarantined rate | 1/7 | [13] |
γ1 | Recovery rate from infected wihout quarantin strategy | 0.033 | Estimated |
γ2 | Recovery rate from quarantin class | 1/18 | [13] |
µ | Death due to disease rate | 0.38 | [19] |
We plot the solution trajectories of model (1) with initial point (15,20,500,1000,150) which converges to COVID-19 equilibrium point P*=(1,27,2773,5428,19371), shown that in Figure 2.
No. | Date | Government measures | β1 |
1 | Feb. 24 2020 | (1) detection of the first case of COVID-19 in Iraq | 0.3 |
(2) quarantined as preliminary control | |||
2 | Feb. 25 2020 | (1) medical examination for all individuals who are in contact with the affected case | 0.1 |
(2) cancellation of some mass gatherings | |||
(3) increase the awareness programs about prevention measures | |||
3 | Feb. 25-Mar. 24 2020 | (1) cancellation of all religious and social events throughout Iraq | 0.09 |
(2) preventing movement between all provinces | |||
(3) the suspension of attendance at universities and schools | |||
(4) providing a number of hospitals to be places for prevention confirmed cases | |||
4 | Mar. 24-Apr. 5 2020 | (1) close all borders with neighboring countries | 0.08 |
(2) to declare a state of emergency and impose a curfew | |||
(3) medical support from the government | |||
(4) methodological improvement on the diagnosis and treatment strategy | |||
(5) spontaneous household quarantine by citizens | |||
(6) more newly-hospitals put into use | |||
(7) massive online teaching in postponed semester | |||
(8) addition of new diagnosis method clinically diagnosis in Baghdad and some provinces |
In the face of the COVID-19 outbreak, many stringent measures were taken by Iraqi government will show in
The following
Clearly, from above figure for effect of contact rate
No. | Date | Government measures | ϵ |
1 | Feb. 24 2020 | (1) quarantined as preliminary control in Iraq | 0.2 |
2 | Feb. 25 2020 | (1) medical examination for all individuals who are in contact with the affected case | 0.4 |
(2) cancellation of some mass gatherings | |||
(3) increase the awareness programs about prevention measures | |||
3 | Feb. 25-Mar. 24 2020 | (1) direct the media to explain the symptoms of the epidemic | 2.5 |
(2) Preventing movement between all provinces | |||
(3) Providing a number of hospitals to be places for prevention confirmed cases | |||
4 | Mar. 24-Apr. 5 2020 | (1) to declare a state of emergency and impose a curfew to reduce the contact between people | 4.5 |
(2) medical support from the government | |||
(3) methodological improvement on the diagnosis and treatment strategy | |||
(4) spontaneous household quarantine by citizens | |||
(5) addition of new diagnosis method clinically diagnosis in Baghdad and some provinces |
The following
Clearly, from above investigate to impact of the quarantined strategy Table 4, when the quarantine strategy increasing we get the number of infected is decrease and other classes are increase. Here, we ask whether the quarantine strategy is the best solution? The answer is possible, but for specific numbers. Whereas, if the quarantine is more than the capacity of the health institutions. We get the dynamical behavior of model (1.1) lose the stability as shown in Figure 5.
In this research, a mathematical model of COVID-19 transmission has been proposed by compartment the total population into five epidemiological status, namely, susceptible S(t), exposed E(t), infected I(t), quarantine Q(t) and recovered R(t). The model incorporates the impact of social awareness programs conducted by public health officials with quarantine strategy in hospital. It has been noticed that these awareness programs and quarantine strategy result in human behavioral changes in order to avoid risk of disease transmission. The model mainly accounts for the reduction in disease class due to awareness. While we can say the disease goes away due to applied the quarantine it well. The proposed model has two biological equilibrium points are COVID-19 free and COVID-19. The COVID-19 free has been local stability when
[1] | El Bayani GF, Marpaung NLE, Simorangkir DAS, et al. (2018) Anti-inflammatory effects of Hibiscus sabdariffa Linn. on the IL-1β/IL-1ra ratio in plasma and hippocampus of overtrained rats and correlation with spatial memory. Kobe J Med Sci 64: E73–E83. |
[2] |
Izquierdo-Vega JA, Arteaga-Badillo DA, Sánchez-Gutiérrez M, et al.(2020) Organic acids from Roselle (Hibiscus sabdariffa L.)-A brief review of its pharmacological effects. Biomedicines 8: 1–16. https://doi.org/10.3390/biomedicines8050100 doi: 10.3390/biomedicines8050100
![]() |
[3] |
Sapian S, Ibrahim Mze AA, Jubaidi FF, et al. (2023) Therapeutic Potential of Hibiscus sabdariffa Linn. in attenuating cardiovascular risk factors. Pharmaceuticals 16: 1–25. https://doi.org/10.3390/ph16060807 doi: 10.3390/ph16060807
![]() |
[4] | Islam A, Jamini TS, Islam M, et al. (2016) Roselle: A functional food with high nutritional and medicinal values. Fundam Appl Agric 1: 44–49. |
[5] |
Tan SL, Sulaiman R (2020) Color and rehydration characteristics of natural red colorant of foam-mat dried Hibiscus sabdariffa L. powder. Int J Fruit Sci 20: 89–105. https://doi.org/10.1080/15538362.2019.1605557 doi: 10.1080/15538362.2019.1605557
![]() |
[6] |
Hamrouni-Sellami I, Rahali FZ, Rebey IB, et al. (2013) Total phenolics, flavonoids, and antioxidant activity of sage (Salvia officinalis L.) plants as affected by different drying methods. Food Bioprocess Technol 6: 806–817. https://doi.org/10.1007/s11947-012-0877-7 doi: 10.1007/s11947-012-0877-7
![]() |
[7] |
Roshanak S, Rahimmalek M, Goli SAH (2016) Evaluation of seven different drying treatments in respect to total flavonoid, phenolic, vitamin C content, chlorophyll, antioxidant activity and color of green tea (Camellia sinensis or C. assamica) leaves. J Food Sci Technol 53: 721–729. https://doi.org/10.1007/s13197-015-2030-x doi: 10.1007/s13197-015-2030-x
![]() |
[8] |
Tajudin NHA, Tasirin SM, Ang WL, et al. (2019) Comparison of drying kinetics and product quality from convective heat pump and solar drying of Roselle calyx. Food Bioprod Process 118: 40–49. https://doi.org/10.1016/j.fbp.2019.08.012 doi: 10.1016/j.fbp.2019.08.012
![]() |
[9] |
Djaeni M, Kumoro AC, Sasongko SB, et al. (2018) Drying rate and product quality evaluation of roselle (Hibiscus sabdariffa L.) calyces extract dried with foaming agent under different temperatures. Int J Food Sci 2018: 9243549. https://doi.org/10.1155/2018/9243549 doi: 10.1155/2018/9243549
![]() |
[10] |
Liu Y, Liu Y, Tao C, et al. (2018) Effect of temperature and pH on stability of anthocyanin obtained from blueberry. J Food Meas Charact 12: 1744–1753. https://doi.org/10.1007/s11694-018-9789-1 doi: 10.1007/s11694-018-9789-1
![]() |
[11] |
Sasongko SB, Djaeni M, Utari FD (2019) Kinetic of anthocyanin degradation in roselle extract dried with foaming agent at different temperatures. Bull Chem React Eng Catal 14: 320–325. https://doi.org/10.9767/bcrec.14.2.2875.320-325 doi: 10.9767/bcrec.14.2.2875.320-325
![]() |
[12] |
Wu HY, Yang KM, Chiang PY (2018) Roselle anthocyanins: antioxidant properties and stability to heat and pH. Molecules 23: 1357. https://doi.org/10.3390/molecules23061357 doi: 10.3390/molecules23061357
![]() |
[13] |
Estiasih T, Witoyo JE, Runtung GKM, et al. (2024) The characteristics of foam-mat dried red and purple roselle calyces powder prepared with commercial emulsifiers as the foaming agents. CYTA-J Food 22: 2356847. https://doi.org/10.1080/19476337.2024.2356847 doi: 10.1080/19476337.2024.2356847
![]() |
[14] |
Enaru B, Drețcanu G, Pop TD, et al. (2021) Anthocyanins: Factors affecting their stability and degradation. Antioxidants 10: 1967. https://doi.org/10.3390/antiox10121967 doi: 10.3390/antiox10121967
![]() |
[15] |
Friedman M, Jürgens HS (2000) Effect of pH on the stability of plant phenolic compounds. J Agric Food Chem 48: 2101–2110. https://doi.org/10.1021/jf990489j doi: 10.1021/jf990489j
![]() |
[16] |
Mattioli R, Francioso A, Mosca L, et al. (2020) Anthocyanins: A comprehensive review of their chemical properties and health effects on cardiovascular and neurodegenerative diseases. Molecules 25: 3809. https://doi.org/10.3390/molecules25173809. doi: 10.3390/molecules25173809
![]() |
[17] |
Maisto M, Marzocchi A, Ciampaglia R, et al. (2024) Effects of food-derived antioxidant compounds on in vitro heavy metal intestinal bioaccessibility. Antioxidants 13: 610. https://doi.org/10.3390/antiox13050610 doi: 10.3390/antiox13050610
![]() |
[18] |
Shruthi VH, Ramachandra CT, Nidoni U, et al. (2017). Physico-chemical, nutritional and functional properties of roselle (Hibiscus sabdariffa L.). Int J Curr Microbiol Appl Sci 6: 1–7. https://doi.org/10.20546/ijcmas.2017.612.347 doi: 10.20546/ijcmas.2017.612.347
![]() |
[19] |
Rocha IDC, Bonnlaender B, Sievers H, et al. (2014). Hibiscus sabdariffa L.—A phytochemical and pharmacological review. Food Chem 165: 424–443. https://doi.org/10.1016/j.foodchem.2014.05.002. doi: 10.1016/j.foodchem.2014.05.002
![]() |
[20] |
Marpaung AM, Paramaputri A (2023) UV-visible light spectra of Clitoria ternatea L. flower extract during aqueous extraction and storage. Int Food Res J. 30: 764–773. https://doi.org/10.47836/ifrj.30.3.18 doi: 10.47836/ifrj.30.3.18
![]() |
[21] |
Samadi S, Fard FR (2020) Phytochemical properties, antioxidant activity and mineral content (Fe, Zn and Cu) in Iranian produced black tea, green tea and roselle calyces. Biocatal Agric Biotechnol 23: 101472. https://doi.org/10.1016/j.bcab.2019.101472 doi: 10.1016/j.bcab.2019.101472
![]() |
[22] |
Huang J, Hu Z, Chin Y, et al. (2023) Improved thermal stability of roselle anthocyanin by co-pigmented with oxalic acid: preparation, characterization and enhancement mechanism. Food Chem 410: 135407. https://doi.org/10.1016/j.foodchem.2023.135407 doi: 10.1016/j.foodchem.2023.135407
![]() |
[23] |
Ifie I, Marshall LJ, Ho P, et al. (2016) Hibiscus sabdariffa (Roselle) extracts and wine: phytochemical profile, physicochemical properties, and carbohydrase inhibition. J Agric Food Chem 64: 4921–4931. https://doi.org/10.1021/acs.jafc.6b01246. doi: 10.1021/acs.jafc.6b01246
![]() |
[24] |
Baliyan S, Mukherjee R, Priyadarshini A, et al. (2022) Determination of antioxidants by DPPH radical scavenging activity and quantitative phytochemical analysis of Ficus religiosa. Molecules 27: 1326. https://doi.org/10.3390/molecules27041326 doi: 10.3390/molecules27041326
![]() |
[25] |
Thaipong K, Boonprakob U, Crosby K, et al. (2006) Comparison of ABTS, DPPH, FRAP, and ORAC Assays for estimating antioxidant activity from guava fruit extracts. J Food Anal 19: 669–675. https://doi.org/10.1016/j.jfca.2006.01.003 doi: 10.1016/j.jfca.2006.01.003
![]() |
[26] | Shruthi VH, Ramachandra CT (2019) Roselle (Hibiscus sabdariffa L.) calyces: A potential source of natural colour and its health benefits. In: Deka SC, Seth D, Hulle VRS (Eds.), Food bioactive: Functionalities and applications in human health, New York: Apple Academic Press, 169–190. https://doi.org/10.1201/9780429242793 |
[27] |
Song W, Yuan Q, Xie Y, et al. (2024) Formulation and characterization of nanocapsules loaded with roselle anthocyanins extract and enhancement of anthocyanins bioaccessibility. Food Chem 459: 140446. https://doi.org/10.1016/j.foodchem.2024.140446 doi: 10.1016/j.foodchem.2024.140446
![]() |
[28] |
Yang D, Xu HX, Guo YX, et al. (2023) Chemical profile of roselle extract and its inhibitory activities on three digestive enzymes in vitro and in vivo. Int J Biol Macromol 253: 126902. https://doi.org/10.1016/j.ijbiomac.2023.126902 doi: 10.1016/j.ijbiomac.2023.126902
![]() |
[29] |
Khoo HE, Azlan A, Tang ST, et al. (2017) Anthocyanidins and anthocyanins: Colored pigments as food, pharmaceutical ingredients, and the potential health benefits. Food Nutr Res 61: 1361779. https://doi.org/10.1080/16546628.2017.1361779 doi: 10.1080/16546628.2017.1361779
![]() |
[30] | Aishah B, Nursabrina M, Noriham A, et al. (2013), Anthocyanins from Hibiscus sabdariffa, Melastoma malabathricum and Ipomoea batatas and its color properties. Int Food Res J 20: 827–834. |
[31] | Marpaung A, Tjahjadi K (2019) The analysis of monomeric anthocyanin by pH differential method is not appropriate for certain anthocyanins. In: Proceedings of the 16th ASEAN Food Conference (16th AFC 2019)—Outlook and Opportunities of Food Technology and Culinary for Tourism Industry, 26–30. https://doi.org/10.5220/0009985400002964 |
[32] |
Dorris MR, Voss DM, Bollom MA, et al. (2018) Browning index of anthocyanin‐rich fruit juice depends on pH and anthocyanin loss more than the gain of soluble polymeric pigments. J Food Sci 83: 911–921. https://doi.org/10.1111/1750-3841.14106 doi: 10.1111/1750-3841.14106
![]() |
[33] |
Gao Q, Li Y, Li Y, et al. (2022) Antioxidant and prooxidant activities of phenolic acids commonly existed in vegetables and their relationship with structures. Food Sci Technol 42: e07622. https://doi.org/10.1590/fst.07622 doi: 10.1590/fst.07622
![]() |
[34] |
Nowak M, Tryniszewski W, Sarniak A, et al. (2022) Concentration dependence of anti-and pro-oxidant activity of polyphenols as evaluated with a light-emitting Fe2+-Egta-H2O2 System. Molecules 27: 3453. https://doi.org/10.3390/molecules27113453 doi: 10.3390/molecules27113453
![]() |
[35] |
Rajashekar CB (2023) Dual role of plant phenolic compounds as antioxidants and prooxidants. Am J Plant Sci 14: 15–28. https://doi.org/10.4236/ajps.2023.141002 doi: 10.4236/ajps.2023.141002
![]() |
[36] |
Wu HY, Yang KM, Chiang PY (2018) Roselle anthocyanins: antioxidant properties and stability to heat and pH. Molecules 23: 1357. https://doi.org/10.3390/molecules23061357 doi: 10.3390/molecules23061357
![]() |
[37] |
Horbowicz M, Kosson R, Grzesiuk A, et al. (2008). Anthocyanins of fruits and vegetables - their occurrence, analysis and role in human nutrition. Veg Crops Res Bull 68: 5–22. https://doi.org/10.2478/v10032-008-0001-8 doi: 10.2478/v10032-008-0001-8
![]() |
[38] |
Punyachareonnon, Deerattrakul V, Luepong K (2021) The Influence of pH, temperature and time on dyeing of silk fabric by black bean anthocyanin-rich extract as colorant. Prog Color Color Coatings 14: 179–186. https://doi.org/10.30509/pccc.2021.81715 doi: 10.30509/pccc.2021.81715
![]() |
[39] |
Millinia BL, Mashithah D, Nawatila R, et al. (2024) Microencapsulation of roselle (Hibiscus sabdariffa L.) anthocyanins: Effects of maltodextrin and trehalose matrix on selected physicochemical properties and antioxidant activities of spray-dried powder. Future Foods 9: 100300. https://doi.org/10.1016/j.fufo.2024.100300 doi: 10.1016/j.fufo.2024.100300
![]() |
[40] |
Idham Z, Putra NR, Aziz AHA, et al. (2022) Improvement of extraction and stability of anthocyanins, the natural red pigment from roselle calyces using supercritical carbon dioxide extraction. J CO2 Util 56: 101839. https://doi.org/10.1016/j.jcou.2021.101839 doi: 10.1016/j.jcou.2021.101839
![]() |
[41] |
Jiang T, Mao Y, Sui L, et al. (2019) Degradation of anthocyanins and polymeric color formation during heat treatment of purple sweet potato extract at different pH. Food Chem 274: 460–470. https://doi.org/10.1016/j.foodchem.2018.07.141 doi: 10.1016/j.foodchem.2018.07.141
![]() |
[42] |
Pasquet PL, Julien-David D, Zhao M, et al. (2024) Stability and preservation of phenolic compounds and related antioxidant activity from agro-food matrix: effect of pH and atmosphere. Food Biosci 57: 103586. https://doi.org/10.1016/j.fbio.2024.103586 doi: 10.1016/j.fbio.2024.103586
![]() |
[43] |
Wang Y, Xing L, Zhang J, et al. (2023) Determination of endogenous phenolic compounds in honey by HPLC-MS/MS. LWT 183: 114951. https://doi.org/10.1016/j.lwt.2023.114951 doi: 10.1016/j.lwt.2023.114951
![]() |
[44] | Krungkri W, Areekul V (2019) Effect of heating condition and pH on stability of total phenolic content and antioxidant activities of samui (Micromelum minutum) extract. In: Proceedings of the 16th ASEAN Food Conference (16th AFC 2019)—Outlook and Opportunities of Food Technology and Culinary for Tourism Industry. Bali, Indonesia, 15–32. https://doi.org/10.5220/0009980801260132 |
[45] |
Chen YT, Kao WT, Lin KW (2008) Effects of pH on the total phenolic compound, antioxidative ability and the stability of dioscorin of various yam cultivars. Food Chem 107: 250–257. https://doi.org/10.1016/j.foodchem.2007.08.017 doi: 10.1016/j.foodchem.2007.08.017
![]() |
[46] |
Rosales-Murillo SS, Sánchez-Bodón J, Hernández Olmos SL, et al. (2024) Anthocyanin-loaded polymers as promising nature-based, responsive, and bioactive materials. Polymers 16: 163. https://doi.org/10.3390/polym16010163 doi: 10.3390/polym16010163
![]() |
[47] |
Cabrita L, Fossen T, Andersen ØM (2000) Colour and stability of the six common anthocyanidin 3-glucosides in aqueous solutions. Food Chem 68: 101–107. https://doi.org/10.1016/S0308-8146(99)00170-3 doi: 10.1016/S0308-8146(99)00170-3
![]() |
[48] |
Rakić V, Ulrih NP (2021) Influence of pH on color variation and stability of cyanidin and cyanidin 3-O-β-glucopyranoside in aqueous solution. CyTA-J Food 19: 174–182. https://doi.org/10.1080/19476337.2021.1874539 doi: 10.1080/19476337.2021.1874539
![]() |
[49] |
Sui X, Dong X, Zhou W (2014) Combined effect of pH and high temperature on the stability and antioxidant activity of two anthocyanins in aqueous solution. Food Chem 163: 163–170. https://doi.org/10.1016/j.foodchem.2014.04.075 doi: 10.1016/j.foodchem.2014.04.075
![]() |
[50] |
Rigolon TCB, Silva RRA, de Oliveira TV, et al. (2024) Exploring anthocyanins-polysaccharide synergies in microcapsule wall materials via spray drying: interaction characterization and evaluation of particle stability. Meas Food 13: 100126. https://doi.org/10.1016/j.meafoo.2023.100126 doi: 10.1016/j.meafoo.2023.100126
![]() |
[51] |
Tena N, Martín J, Asuero AG (2020) State of the art of anthocyanins: antioxidant activity, sources, bioavailability, and therapeutic effect in human health. Antioxidants 9: 451. https://doi.org/10.3390/antiox9050451 doi: 10.3390/antiox9050451
![]() |
[52] |
Floegel A, Kim DO, Chung SJ, et al. (2011) Comparison of ABTS/DPPH assays to measure antioxidant activity in popular antioxidant-rich US foods. J Food Compos Anal 24: 1043–1048. https://doi.org/10.1016/j.jfca.2011.01.008 doi: 10.1016/j.jfca.2011.01.008
![]() |
[53] |
Bayliak MM, Burdyliuk NI, Lushchak VI (2016) Effects of pH on antioxidant and prooxidant properties of common medicinal herbs. Open Life Sci 11: 298–307. https://doi.org/10.1515/biol-2016-0040 doi: 10.1515/biol-2016-0040
![]() |
[54] |
Sun HN, Mu TH, Xi LS (2017) Effect of pH, heat, and light treatments on the antioxidant activity of sweet potato leaf polyphenols. Int J Food Prop 20: 318–332. https://doi.org/10.1080/10942912.2016.1160410 doi: 10.1080/10942912.2016.1160410
![]() |
[55] |
Kungsuwan K, Singh K, Phetkao S, et al. (2014) Effect of pH and anthocycnin concentration on colour and antioxidant activity of Clitorea ternatea extract. Food Appl Biosci J 2: 31–46. https://doi.org/10.14456/fabj.2014.3 doi: 10.14456/fabj.2014.3
![]() |
[56] |
Yu L, Wu Y, Liu D, et al. (2022) The kinetic behavior of antioxidant activity and the stability of aqueous and organic polyphenol extracts from navel orange peel. Food Sci Technol 42 :e90621. https://doi.org/10.1590/fst.90621 doi: 10.1590/fst.90621
![]() |
[57] |
Kamiloglu S, Capanoglu E, Grootaert C, et al. (2015) Anthocyanin absorption and metabolism by human intestinal Caco2-cells—A review. Int J Mol Sci 16: 21555–21574. https://doi.org/10.3390/ijms160921555 doi: 10.3390/ijms160921555
![]() |
[58] |
Kudličková Z, Michalková R, Salayová A, et al. (2023) Design, synthesis, and evaluation of novel indole hybrid chalcones and their antiproliferative and antioxidant activity. Molecules 28: 6583. https://doi.org/10.3390/molecules2818658 doi: 10.3390/molecules2818658
![]() |
1. | So Im Ryu, BeLong Cho, Sun Ju Chang, Hana Ko, Yu Mi Yi, Eun-Young Noh, Hye Ryung Cho, Yeon-Hwan Park, Factors Related to Self-Confidence to Live Alone in Community-Dwelling Older Adults: A Cross-Sectional Study, 2021, 21, 1471-2318, 10.1186/s12877-021-02214-w | |
2. | SuJung Jung, Sunghee H. Tak, Factors of Functional Disability in the Social Participation of Older Adults Living Alone With Fall Experience, 2022, 41, 0733-4648, 2197, 10.1177/07334648221104791 | |
3. | Débora Aparecida Silva de Jesus, Nayara Gomes Nunes Oliveira, Neilzo Nunes Oliveira, Alisson Fernandes Bolina, Gianna Fiori Marchiori, Darlene Mara dos Santos Tavares, Apoio social entre mulheres e homens idosos compreendido por meio da modelagem de equações estruturais, 2022, 75, 1984-0446, 10.1590/0034-7167-2022-0188pt | |
4. | Juan Fang, Jianping Ren, Lixian Ren, Xiantao Qiu, Shuang Yuan, Wenting Wang, Jinjing Wang, Perceived Social Support and Associated Factors Among Community-Dwelling Older Adults With Frailty and Pre-frailty in Hangzhou, China, 2022, 13, 1664-0640, 10.3389/fpsyt.2022.944293 | |
5. | Li Song, Yan Ge, Xuyang Zhang, The Relationship Between WeChat Use by Chinese Urban Older Adults Living Alone and Their Subjective Well-Being: The Mediation Role of Intergenerational Support and Social Activity, 2021, Volume 14, 1179-1578, 1543, 10.2147/PRBM.S330827 | |
6. | Chanhyun Park, Daniel Kim, Becky A. Briesacher, Association of Social Isolation of Long-term Care Facilities in the United States With 30-Day Mortality, 2021, 4, 2574-3805, e2113361, 10.1001/jamanetworkopen.2021.13361 | |
7. | Fengyan Tang, Ke Li, Heejung Jang, Longitudinal relationship between living alone and health among Chinese older adults: the mediating role of activity engagement, 2022, 1752-5098, 1, 10.1080/17525098.2022.2121738 | |
8. | Débora Aparecida Silva de Jesus, Nayara Gomes Nunes Oliveira, Neilzo Nunes Oliveira, Alisson Fernandes Bolina, Gianna Fiori Marchiori, Darlene Mara dos Santos Tavares, Social support among older adults understood through structural equation modeling, 2022, 75, 1984-0446, 10.1590/0034-7167-2022-0188 | |
9. | MoonKi Choi, Juyeon Bae, ‘I eat to not die’: Diet and exercise experiences of older adults living alone, 2023, 18, 1748-3735, 10.1111/opn.12523 | |
10. | Regina Roofeh, Sean A. P. Clouston, Dylan M. Smith, Competing Risk Analysis of Time to Communal Residence for Elder Orphans, 2022, 41, 0733-4648, 2105, 10.1177/07334648221098994 | |
11. | Qiuhong Li, Chao Wu, Social Interaction, Lifestyle, and Depressive Status: Mediators in the Longitudinal Relationship between Cognitive Function and Instrumental Activities of Daily Living Disability among Older Adults, 2022, 19, 1660-4601, 4235, 10.3390/ijerph19074235 | |
12. | Rachel Missell-Gray, Kimberly Van Orden, Adam Simning, Hospitalization’s association with depression in adults over 50 years old: does living arrangement matter? Findings from the Health and Retirement Study, 2023, 1360-7863, 1, 10.1080/13607863.2022.2163978 | |
13. | Sevinc Tastan, Hatice Bebis, Psychometric properties of a Turkish version of the social activities scale for community‐dwelling older people requiring support, 2024, 19, 1748-3735, 10.1111/opn.12593 | |
14. | Loai Issa Tawalbeh, The relationship between perceived social support and self-care behaviors among patients with heart failure in Jordan, 2024, 43, 1046-1310, 19775, 10.1007/s12144-024-05793-0 | |
15. | Alline Beleigoli, Hila Ariela Dafny, Maria Alejandra Pinero de Plaza, Claire Hutchinson, Tania Marin, Joyce S. Ramos, Orathai Suebkinorn, Lemlem G. Gebremichael, Norma B. Bulamu, Wendy Keech, Marie Ludlow, Jeroen Hendriks, Vincent Versace, Robyn A. Clark, Clinical effectiveness of cardiac rehabilitation and barriers to completion in patients of low socioeconomic status in rural areas: A mixed-methods study, 2024, 38, 0269-2155, 837, 10.1177/02692155241236998 | |
16. | Lai Kun Tong, Yue Yi Li, Yong Bing Liu, Mu Rui Zheng, Guang Lei Fu, Mio Leng Au, The mediating role of sleep quality in the relationship between family health and depression or anxiety under varying living status, 2025, 369, 01650327, 345, 10.1016/j.jad.2024.10.004 | |
17. | Yueming Ding, Huiying Zhang, Zhiqing Hu, Yanjun Sun, Yiping Wang, Baolong Ding, Guofeng Yue, Yuan He, Perceived Social Support and Health-Related Quality of Life Among Hypertensive Patients: A Latent Profile Analysis and the Role of Delay Discounting and Living Alone, 2024, Volume 17, 1179-1594, 2125, 10.2147/RMHP.S476633 | |
18. | Irene Instenes, Kyrre Breivik, Britt Borregaard, Alf Inge Larsen, Heather Allore, Bjørn Bendz, Christi Deaton, Svein Rotevatn, Tone Merete Norekvål, Phenotyping Self-Reported Health Profiles in Octogenarians and Nonagenarians After Percutaneous Coronary Intervention: A Latent Profile Analysis, 2023, 32, 14439506, 1321, 10.1016/j.hlc.2023.09.004 | |
19. | Wonkyung Jung, Mia Vogel, Karl Cristie F Figuracion, Eeeseung Byun, Hilaire Thompson, The Perceived Meaning of Traumatic Brain Injury for Older Adults: A Longitudinal-Multiple Case Study, 2024, 49, 0278-4807, 14, 10.1097/RNJ.0000000000000445 | |
20. | Paula Steinhoff, Amelie Reiner, Physical activity and functional social support in community-dwelling older adults: a scoping review, 2024, 24, 1471-2458, 10.1186/s12889-024-18863-6 | |
21. | Szu-Yu Chen, Kuei-Min Chen, Chiang-Ching Chang, Ching-Yi Lai, Frank Belcastro, Chuan-Feng Kuo, Social Skill Abilities and Demographic Correlates of Older Volunteers, 2024, 43, 0733-4648, 1419, 10.1177/07334648241245487 | |
22. | Du-Ri Kim, Ting-Fu Lai, Minji Sung, Minwoo Jang, Yeo-Kyung Shin, Young jin Ra, Yung Liao, Jong-Hwan Park, Myung-Jun Shin, Effect of information and communication technology-based smart care services for physical and cognitive functions in older adults living alone: A quasi-experimental study, 2024, 28, 12797707, 100318, 10.1016/j.jnha.2024.100318 | |
23. | Daniel Jung, Jeong Ha (Steph) Choi, Kerstin Gerst Emerson, Discharge disposition for home health care patients with Alzheimer's disease and related dementia: The role of living arrangements and rural living, 2024, 0890-765X, 10.1111/jrh.12872 | |
24. | Jiyoung Shin, Hun Kang, Seongmi Choi, JiYeon Choi, Exploring social activity patterns among community-dwelling older adults in South Korea: a latent class analysis, 2024, 24, 1471-2318, 10.1186/s12877-024-05287-5 | |
25. | Abigail T. Stephan, Hye Won Chai, Ava McVey, Briana N. Sprague, Annamaria V. Wolf, Christine B. Phillips, Lesley A. Ross, Differential Longitudinal Associations Between Depressive Symptoms and Cognitive Status by Living Situation in Older Adults, 2024, 0733-4648, 10.1177/07334648241285602 | |
26. | Meiqian Chen, Xiang Cao, Afeng Wang, Yi Zhu, Guanzhen Lu, Li Zhang, Lijuan Shen, A global perspective on risk factors for social isolation in community-dwelling older adults: A systematic review and meta-analysis, 2024, 116, 01674943, 105211, 10.1016/j.archger.2023.105211 | |
27. | Julia Ortmann, Jette Möller, Yvonne Forsell, Yajun Liang, The Dual Trajectories of Depressive Symptoms and Social Support—A Population‐Based Cohort Study Among Swedish Adults Across 23 Years, 2024, 2575-5609, n/a, 10.1176/appi.prcp.20240063 | |
28. | Youngmin Cho, Donruedee Kamkhoad, Natalie G. Regier, Lixin Song, Ruth A. Anderson, Bei Wu, Baiming Zou, Anna S. Beeber, Coping with cognitive decline in older adults with mild cognitive impairment or mild dementia: a scoping review, 2025, 1360-7863, 1, 10.1080/13607863.2025.2453819 | |
29. | Ali Gökhan Gölçek, The Dynamics of Poverty Among Türkiye’s Aging: An Investigative Study of Determinants, 2025, 1874-7884, 10.1007/s12062-025-09482-z | |
30. | Kimia Ghasemi, Mahsa Fallahi, Mohamad Molaei Qelichi, Hiva Farmahini Farahani, Kasra Dolatkhahi, Factors contributing to urban isolation: A mixed-methods analysis of three new towns in Tehran, 2025, 161, 02642751, 105863, 10.1016/j.cities.2025.105863 | |
31. | Jichao Zheng, Zeqiang Ni, Living arrangements, health outcomes, and the buffering role of social capital among older adults in China, 2025, 13, 2296-2565, 10.3389/fpubh.2025.1469914 | |
32. | Siwei Sun, Xuechun Wang, Na Guo, Peipei Li, Ruoxi Ding, Dawei Zhu, Association between catastrophic health expenditure and mental health among elderly in China: the potential role of income and social activity, 2025, 25, 1471-2318, 10.1186/s12877-025-05887-9 |
Cases | D1 | D2 | D3 | D4 | D5 | R0 | Number of sign changes | Number of possible positive real roots |
1 | − | + | + | + | + | ℛ0 > 1 | 1 | 1 |
− | + | + | + | − | ℛ0 < 1 | 2 | 0,2 | |
2 | − | + | + | − | + | ℛ0 > 1 | 3 | 1,3 |
− | + | + | − | − | ℛ0 < 1 | 2 | 0,2 | |
3 | − | + | − | + | + | ℛ0 > 1 | 3 | 1,3 |
− | + | − | + | − | ℛ0 < 1 | 4 | 0,2,4 | |
4 | − | + | − | − | + | ℛ0 > 1 | 3 | 1,3 |
− | + | − | − | − | ℛ0 < 1 | 2 | 0,2 | |
5 | − | − | + | + | + | ℛ0 > 1 | 1 | 1 |
− | − | + | + | − | ℛ0 < 1 | 2 | 0,2 | |
6 | − | − | + | − | + | ℛ0 > 1 | 3 | 1,3 |
− | − | + | − | − | ℛ0 < 1 | 2 | 0,2 | |
7 | − | − | − | + | + | ℛ0 > 1 | 1 | 1 |
− | − | − | + | − | ℛ0 < 1 | 2 | 0,2 | |
8 | − | − | − | − | + | ℛ0 > 1 | 1 | 1 |
− | − | − | − | − | ℛ0 < 1 | 0 | 0 |
Parameter | Definition | Value | Source |
A | Birth rate | 1541.8 | [19] |
β1 | Transmission contact rate between S and I | 0.5 | Estimated |
c | Fraction constant | [0–1] | Estimated |
β2 | Awareness rate | 0.1 | Estimated |
m | Half saturation of media constant | 70 | Estimated |
d | Natural death rate | 3.854510−5 | [19],[20] |
k | Fraction denoting the level of exogenous re-infection | 0.05 | Estimated |
ϵ | Quarantined rate | 1/7 | [13] |
γ1 | Recovery rate from infected wihout quarantin strategy | 0.033 | Estimated |
γ2 | Recovery rate from quarantin class | 1/18 | [13] |
µ | Death due to disease rate | 0.38 | [19] |
No. | Date | Government measures | β1 |
1 | Feb. 24 2020 | (1) detection of the first case of COVID-19 in Iraq | 0.3 |
(2) quarantined as preliminary control | |||
2 | Feb. 25 2020 | (1) medical examination for all individuals who are in contact with the affected case | 0.1 |
(2) cancellation of some mass gatherings | |||
(3) increase the awareness programs about prevention measures | |||
3 | Feb. 25-Mar. 24 2020 | (1) cancellation of all religious and social events throughout Iraq | 0.09 |
(2) preventing movement between all provinces | |||
(3) the suspension of attendance at universities and schools | |||
(4) providing a number of hospitals to be places for prevention confirmed cases | |||
4 | Mar. 24-Apr. 5 2020 | (1) close all borders with neighboring countries | 0.08 |
(2) to declare a state of emergency and impose a curfew | |||
(3) medical support from the government | |||
(4) methodological improvement on the diagnosis and treatment strategy | |||
(5) spontaneous household quarantine by citizens | |||
(6) more newly-hospitals put into use | |||
(7) massive online teaching in postponed semester | |||
(8) addition of new diagnosis method clinically diagnosis in Baghdad and some provinces |
No. | Date | Government measures | ϵ |
1 | Feb. 24 2020 | (1) quarantined as preliminary control in Iraq | 0.2 |
2 | Feb. 25 2020 | (1) medical examination for all individuals who are in contact with the affected case | 0.4 |
(2) cancellation of some mass gatherings | |||
(3) increase the awareness programs about prevention measures | |||
3 | Feb. 25-Mar. 24 2020 | (1) direct the media to explain the symptoms of the epidemic | 2.5 |
(2) Preventing movement between all provinces | |||
(3) Providing a number of hospitals to be places for prevention confirmed cases | |||
4 | Mar. 24-Apr. 5 2020 | (1) to declare a state of emergency and impose a curfew to reduce the contact between people | 4.5 |
(2) medical support from the government | |||
(3) methodological improvement on the diagnosis and treatment strategy | |||
(4) spontaneous household quarantine by citizens | |||
(5) addition of new diagnosis method clinically diagnosis in Baghdad and some provinces |
Cases | D1 | D2 | D3 | D4 | D5 | R0 | Number of sign changes | Number of possible positive real roots |
1 | − | + | + | + | + | ℛ0 > 1 | 1 | 1 |
− | + | + | + | − | ℛ0 < 1 | 2 | 0,2 | |
2 | − | + | + | − | + | ℛ0 > 1 | 3 | 1,3 |
− | + | + | − | − | ℛ0 < 1 | 2 | 0,2 | |
3 | − | + | − | + | + | ℛ0 > 1 | 3 | 1,3 |
− | + | − | + | − | ℛ0 < 1 | 4 | 0,2,4 | |
4 | − | + | − | − | + | ℛ0 > 1 | 3 | 1,3 |
− | + | − | − | − | ℛ0 < 1 | 2 | 0,2 | |
5 | − | − | + | + | + | ℛ0 > 1 | 1 | 1 |
− | − | + | + | − | ℛ0 < 1 | 2 | 0,2 | |
6 | − | − | + | − | + | ℛ0 > 1 | 3 | 1,3 |
− | − | + | − | − | ℛ0 < 1 | 2 | 0,2 | |
7 | − | − | − | + | + | ℛ0 > 1 | 1 | 1 |
− | − | − | + | − | ℛ0 < 1 | 2 | 0,2 | |
8 | − | − | − | − | + | ℛ0 > 1 | 1 | 1 |
− | − | − | − | − | ℛ0 < 1 | 0 | 0 |
Parameter | Definition | Value | Source |
A | Birth rate | 1541.8 | [19] |
β1 | Transmission contact rate between S and I | 0.5 | Estimated |
c | Fraction constant | [0–1] | Estimated |
β2 | Awareness rate | 0.1 | Estimated |
m | Half saturation of media constant | 70 | Estimated |
d | Natural death rate | 3.854510−5 | [19],[20] |
k | Fraction denoting the level of exogenous re-infection | 0.05 | Estimated |
ϵ | Quarantined rate | 1/7 | [13] |
γ1 | Recovery rate from infected wihout quarantin strategy | 0.033 | Estimated |
γ2 | Recovery rate from quarantin class | 1/18 | [13] |
µ | Death due to disease rate | 0.38 | [19] |
No. | Date | Government measures | β1 |
1 | Feb. 24 2020 | (1) detection of the first case of COVID-19 in Iraq | 0.3 |
(2) quarantined as preliminary control | |||
2 | Feb. 25 2020 | (1) medical examination for all individuals who are in contact with the affected case | 0.1 |
(2) cancellation of some mass gatherings | |||
(3) increase the awareness programs about prevention measures | |||
3 | Feb. 25-Mar. 24 2020 | (1) cancellation of all religious and social events throughout Iraq | 0.09 |
(2) preventing movement between all provinces | |||
(3) the suspension of attendance at universities and schools | |||
(4) providing a number of hospitals to be places for prevention confirmed cases | |||
4 | Mar. 24-Apr. 5 2020 | (1) close all borders with neighboring countries | 0.08 |
(2) to declare a state of emergency and impose a curfew | |||
(3) medical support from the government | |||
(4) methodological improvement on the diagnosis and treatment strategy | |||
(5) spontaneous household quarantine by citizens | |||
(6) more newly-hospitals put into use | |||
(7) massive online teaching in postponed semester | |||
(8) addition of new diagnosis method clinically diagnosis in Baghdad and some provinces |
No. | Date | Government measures | ϵ |
1 | Feb. 24 2020 | (1) quarantined as preliminary control in Iraq | 0.2 |
2 | Feb. 25 2020 | (1) medical examination for all individuals who are in contact with the affected case | 0.4 |
(2) cancellation of some mass gatherings | |||
(3) increase the awareness programs about prevention measures | |||
3 | Feb. 25-Mar. 24 2020 | (1) direct the media to explain the symptoms of the epidemic | 2.5 |
(2) Preventing movement between all provinces | |||
(3) Providing a number of hospitals to be places for prevention confirmed cases | |||
4 | Mar. 24-Apr. 5 2020 | (1) to declare a state of emergency and impose a curfew to reduce the contact between people | 4.5 |
(2) medical support from the government | |||
(3) methodological improvement on the diagnosis and treatment strategy | |||
(4) spontaneous household quarantine by citizens | |||
(5) addition of new diagnosis method clinically diagnosis in Baghdad and some provinces |