FTCS Research Articles

Anti-disturbance control for HVs system subject to nonlinear actuator characteristics with extended state observer

This paper proposes a radial basis function neural network and the actuator fault extended state observer based fast non-terminal sliding mode fault-tolerant control scheme for hypersonic vehicles (HVs) system. The proposed scheme can cope with actuator faults, actuator saturation, parameter uncertainties, and external disturbances for HVs systems, without relying on redundancy as some passive FTC methods do. Moreover, an anti-windup compensator is designed to mitigate the input saturation effects. Furthermore, the finite-time stability of the attitude angle of the HVs system is proved by Lyapunov's theorem. Numerical simulations validate the effectiveness of the proposed scheme.

Fourth-Order Numerical Solutions for a Fuzzy Time-Fractional Convection–Diffusion Equation under Caputo Generalized Hukuhara Derivative

The fuzzy fractional differential equation explains more complex real-world phenomena than the fractional differential equation does. Therefore, numerous techniques have been timely derived to solve various fractional time-dependent models. In this paper, we develop two compact finite difference schemes and employ the resulting schemes to obtain a certain solution for the fuzzy time-fractional convection–diffusion equation. Then, by making use of the Caputo fractional derivative, we provide new fuzzy analysis relying on the concept of fuzzy numbers. Further, we approximate the time-fractional derivative by using a fuzzy Caputo generalized Hukuhara derivative under the double-parametric form of fuzzy numbers. Furthermore, we introduce new computational techniques, based on fuzzy double-parametric form, to shift the given problem from one fuzzy domain to another crisp domain. Moreover, we discuss some stability and error analysis for the proposed techniques by using the Fourier method. Over and above, we derive several numerical experiments to illustrate reliability and feasibility of our proposed approach. It was found that the fuzzy fourth-order compact implicit scheme produces slightly better results than the fourth-order compact FTCS scheme. Furthermore, the proposed methods were found to be feasible, appropriate, and accurate, as demonstrated by a comparison of analytical and numerical solutions at various fuzzy values.

Bioactive compound content and antioxidant activities of analog rice enriched with the germinated of white corn (zea mays) and the germinated of mung bean (vigna radiata)

The research aimed to know bio-active compounds’ content and antioxidant activity of rice analog based on germinated white corn (Zea mays), germinated mung bean (Vigna radiata) and white sweet potatoes. There were several stages: first, the formulation of analog rice—the second analyzes of total phenol and flavonoids content. The third is the analysis of antioxidant activity done by DPPH, FTC, and TBA methods. Results showed that formulation I TPC levels are 385.00 ± 0.04 (mgGAE/100g), TFC 267.60 ± 0.42 (mgQCE/100g). Formulation II TPC levels are 379.20 ± 0.85 (mgGAE/100g), TFC 235.40 ± 0.92 (mgQCE/100g). Formulation III TPC levels are 346.50 ± 0.85 (mgGAE/100g), TFC 227.00 ± 0.42 (mgQCE/100g). Antioxidant activity formulation I with DPPH method: 67.71 ± 0.20%; The percentage inhibitory with the FTC 69.10 ± 1.01%, TBA 65.28 ± 0.28%. Antioxidant activity formulation II with DPPH method: 66.57 ± 0.20%; The percentage inhibitory with the FTC 60.63 ± 0.81%, TBA method 64.42 ± 0.58%. Antioxidant activity formulation III with DPPH method: 63.57 ± 0.20%; The percentage inhibitory with the FTC 45.41 ± 0.30%, TBA 63.21 ± 0.58%. There is a significant and positive correlation between bioactive compounds with three methods of antioxidant activity used.

Antioxidant and anti-gastroenteritis activities of <i>Funtumia elastica</i> (Apocynaceae) and <i>Caesalpinia bonduc</i> (Caeasalpiniaceae)

Oxidative stress and infectious diseases are health problems on a global scale. The aim of this study was to evaluate the antioxidant and anti-gastroenteritis activities of hydroethanolic extracts of leaves of Funtumia elastica and Caesalpinia bonduc. After obtaining the hydroethanolic extracts, the phytochemical tests were carried out. The antioxidant activity was evaluated by different assays using 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and lipid peroxidation inhibition (FTC and TBARS methods). The agar well diffusion method was used to determine the antibacterial activity to the plant extract. The triphytochemical study has revealed that these plants extracts contain a diversity of secondary metabolites. F. elastica gave a good anti-radical activity (IC50 = 36 μg/ml). F. elastica recorded the highest rate of inhibition of lipid peroxidation with 63% (FTC method) and 65% (TBARS method). C. bonduc extract (200 mg/ml) inhibited the in vitro growth of all the bacterial strains studied in this study with inhibition diameters that evolved between 9 mm and 13 mm. These plant extracts could be used if they are improved for the treatment of gastroenteritis related to Shigella and Escherichia coli and in the care of pathologies related to oxidative stress.
 © 2020 International Formulae Group. All rights reserved.
 Keywords: Antioxidant, anti-gastroenteritis, Funtumia elastica, Caesalpinia bonduc, hydroethanolic extracts

Effects of light intensity on growth, quality and antioxidant activities of Sedum sarmentosum

The present study was conducted to explore the effect of light intensity on growth, bioactivity compounds accumulation and anti-oxidative activity of Sedum sarmentosum. The growth, yield, contents of total flavonoids, total phenolic, quercetin, kaempferol and isorhamnetin, and antioxidant activities were assessed in S. sarmentosum under five light intensities, namely 100% full sunlight (G1), 77% full sunlight (G2), 60% full sunlight (G3), 38% full sunlight (G4), and 16% full sunlight (G5). The results showed that light intensity significantly affected the growth and the chemical compounds accumulation. With the decrease of light intensity, the maximum branch length and the average internode distance increased. G2 treatment greatly promoted the numbers of leaf layers and branches, and G3 treatment remarkably improved the yield. The highest total flavonoids and phenolic contents were obtained in G3 treatment. Meanwhile, the highest quercetin and isorhamnetin contents were obtained in G1 treatment. The difference of kaempferol content was not significant. In addition, based on DPPH, FTC and FRAP methods, the antioxidant activities of the aqueous extracts under G1 treatment were superior to the others. The results indicated that more than 60% full sunlight was the optimum light intensity condition to achieve high yield and quality of S. sarmentosum.

The two-level finite difference schemes for the heat equation with nonlocal initial condition

In this paper, the two-level finite difference schemes for the one-dimensional heat equation with a nonlocal initial condition are analyzed. As the main result, we obtain conditions for the numerical stability of the schemes. In addition, we revise the stability conditions obtained in [21] for the Crank–Nicolson scheme. We present several numerical examples that confirm the theoretical results within linear, as well as nonlinear problems. In some particular cases, it is shown that for small regions of the time step size values, the explicit FTCS scheme is stable while certain implicit methods, such as Crank–Nicolson scheme, are not.

Achieving a Sustainable Environment using Numerical Method for the Solution of Advection Equation in Fluid Dynamics

The paper compares some explicit numerical methods for solving the advection equation that could be used to describe transportation of a pollutant in one direction. The one-dimensional advection equation is solved by using five different standard finite difference schemes (the Upwind, FTCS, Lax- Friedrichs, Lax wendroff and Leith’s methods) via C codes. An example is used for comparison; the numerical results are compared with analytical solution. It is found that, for the example studied, all the explicit finite difference methods give satisfactory solutions to the advection problem.

Forward Time Centered Space Scheme for the Solution of Transport Equation

Transport phenomenon is central for understanding many procedures in numerous sciences, transport phenomena can be described by the partial differential equation. Forward Time Centered Space scheme give ample numerical solutions of the transport equation. In this paper, we apply Forward Time Centered Space scheme to solve a non-trivial transport problem using different step sizes of time (t) and space (x). We use MATLAB software to get the numerical results. The numerical simulation presents that the FTCS scheme is more stable and closer to the exact solution when we decrease step sizes of t, x and more and more.

Free radical scavenging activity and lipid peroxidation inhibition of Hypericum helianthemoides (spach) Boiss

Antioxidants are compounds that obstruct the oxidation of macromolecules in the body. In general, there are two categories of antioxidants, natural and synthetic. Recently, interest has been increased considerably for obtaining new natural antioxidants. In this study, the scavenging of free radicals such as DPPH, NO and OH by Hypericum helianthemoides extract was evaluated. Also, the antioxidant properties of this extract were evaluated by FRAP, FTC methods and determination phenolic compounds. The plant was collected from north of Fars Province and plant extraction was obtained using ethanol. In DPPH radical scavenging, different concentrations of the Hypericum extract were added to DPPH radical. In hydroxyl radical scavenging, Fenton reaction mixture, TCA and TBA were mixed with Hypericum extract. In nitric radical scavenging, nitropruside was mixed with Hypericum extract and then sulphanilic acid, naphthylene diamine were added. In determination of phenolic compounds, Folin-ciocalteu and sodium carbonate were added to Hypericum extract. In DPPH radical scavenging, the IC50 of Hypericum extract (309.35±6.5µg/ml) was higher than the antioxidant standards, BHT (IC50=81.9±2.6 µg/ml) and quercetin (IC50=60.04±6.48 µg/ml). The highest scavenging of hydroxyl radicals was observed in Hypericum extract (70.3±0.8%, 125 µg/ml). In gallic acid it was (73.8±3.3%). In 200 µg/ml of Hypericum extract scavenged NO radical (85.2±2.7%). In FRAP method, the IC50 of this extract was 109.7±10.5 µg/ml. In FTC method, the inhibition of lipid peroxidation by Hypericum extract, BHT and ascorbic acid were 59.2±2.2, 66.9±0.15, 64.06±0.02 respectively. Total phenol of the plant extract was 3±0.4 mg/g.//

Antioxidant Activity and Phytochemical Screening of Crude Endophytes Extracts of <i>Tabebuia argentea</i> Bur. & K. Sch.

The aim of this study is to investigate in vitro antioxidant activities and the phytochemical screening endophytes. Seven different endophytic fungi were isolated from different parts of the plant and their extracts subjected to know antioxidant properties and phytochemical screening. Phytochemical analysis revealed the presence of tannins, flavonoids, steroids, alkaloids, phenols and proteins from different solvents extracts of different endophytes. The antioxidant activity was evaluated by six separated methods: scavenging of free radical DPPH, FRAP, TBA, superoxide radical, FTC and iron methods. All seven different endophytes yielded almost all phytochemicals in methanol extracts which were tested. The endophytes A. niger, Penicillium sp. and Trichoderma sp. have shown potential in vitro antioxidant activities. Further work is needful to isolate the exact compound which is responsible for antioxidant activity and biophysical characterization will be done in the future.

Synthesis of damnacanthal, a naturally occurring 9,10-anthraquinone and its analogues, and its biological evaluation against five cancer cell lines

Damnacanthal and nordamnacanthal, two naturally occurring 9,10-anthraquinones, and their analogues were synthesized. Cytotoxic activity against five cancer cell lines was evaluated using MTT assay. 2-Bromomethyl-1,3-dimethoxyanthraquinone was found to display the highest activity against all cell lines with IC50 range of 2–8 μM. Structure–activity relationship (SAR) assessment was considered to rationalise the cytotoxic effect. Bromomethyl group at position C-2 of the anthraquinone was found to be important in exerting cytotoxic activity of this class of compounds. The presence of the flanking methoxyl or hydroxyl groups at C-1 and C-3 also contributes to this activity. Finally, the antioxidant effect of these compounds was evaluated. MTT assay was used to measure the cytotoxicity against different cancer cell lines. Antioxidant activity was measured by FTC and TBA methods. Only two anthraquinones, damnacanthal and nordamnacanthal, were found to be antioxidative.

A novel self consistent calculation approach for the capacitance‐voltage characteristics of semiconductor quantum wire transistors based on a split‐gate configuration

PurposeThe purpose of this paper is to develop an efficient numerical algorithm for the self‐consistent solution of Schrodinger and Poisson equations in one‐dimensional systems. The goal is to compute the charge‐control and capacitance‐voltage characteristics of quantum wire transistors.Design/methodology/approachThe paper presents a numerical formulation employing a non‐uniform finite difference discretization scheme, in which the wavefunctions and electronic energy levels are obtained by solving the Schrödinger equation through the split‐operator method while a relaxation method in the FTCS scheme (“Forward Time Centered Space”) is used to solve the two‐dimensional Poisson equation.FindingsThe numerical model is validated by taking previously published results as a benchmark and then applying them to yield the charge‐control characteristics and the capacitance‐voltage relationship for a split‐gate quantum wire device.Originality/valueThe paper helps to fulfill the need for C‐V models of quantum wire device. To do so, the authors implemented a straightforward calculation method for the two‐dimensional electronic carrier density n(x,y). The formulation reduces the computational procedure to a much simpler problem, similar to the one‐dimensional quantization case, significantly diminishing running time.

Comparative antioxidant activity of an extract of Lithraea molleoides and an isolated 5‐alkyl resorcinol derivative. Effects on the proliferation of normal and tumoral lymphocytes

Lithraea molleoides (Vell.) Engl. (Anacardiaceae), is known in South America for its medicinal properties: antiarthritic, haemostatic, diuretic, tonic and useful for the treatment of respiratory diseases. Previously the isolation of a new cytotoxic 5-alkyl resorcinol derivative, 1,3-dihydroxy-5-(tridec-4',7'-dienyl) benzene, from a dichloromethane extract (DM) was reported. The aim of this work was to determine and to compare the antioxidant activity of DM and the isolated compound, 1,3-dihydroxy-5-(tridec-4',7'-dienyl) benzene. Moreover, the activity of both on the proliferation of tumoral and normal lymphocytes was determined. The compound was isolated and quantified by HPLC. The compound represented 0.036% of DM. The extract and the compound exerted antioxidant activity by DPPH and FTC methods. On tumoral cells, both exerted antiproliferative action but the compound was more active (EC(50) : 17.4 ± 1 µg/mL). On normal lymphocytes, both exerted a stimulatory effect on cell proliferation inversely related to concentration, the extract was more active than the compound (maximum effect: 300 ± 20% of stimulation). Most of the effects observed with the extract were independent of the isolated compound. DM could be an important source of antioxidant and immunomodulatory compounds to be studied on cancer diseases.

Text clustering using frequent itemsets

Frequent itemset originates from association rule mining. Recently, it has been applied in text mining such as document categorization, clustering, etc. In this paper, we conduct a study on text clustering using frequent itemsets. The main contribution of this paper is three manifolds. First, we present a review on existing methods of document clustering using frequent patterns. Second, a new method called Maximum Capturing is proposed for document clustering. Maximum Capturing includes two procedures: constructing document clusters and assigning cluster topics. We develop three versions of Maximum Capturing based on three similarity measures. We propose a normalization process based on frequency sensitive competitive learning for Maximum Capturing to merge cluster candidates into predefined number of clusters. Third, experiments are carried out to evaluate the proposed method in comparison with CFWS, CMS, FTC and FIHC methods. Experiment results show that in clustering, Maximum Capturing has better performances than other methods mentioned above. Particularly, Maximum Capturing with representation using individual words and similarity measure using asymmetrical binary similarity achieves the best performance. Moreover, topics produced by Maximum Capturing distinguished clusters from each other and can be used as labels of document clusters.

Determination of antioxidant activity of various extracts of Parmelia saxatilis

The work was conducted with the purpose to evaluate antioxidant activity of Parmelia saxatilis (PS) by different analytical methods. Water and methanol were used as solvents and antioxidative effects were measured by a ferric thiocyanate method (FTC) and thiobarbituric acid test (TBA). The antioxidant activity increased with the increasing amount of extracts (from 50 to 250 µg) added to linoleic acid emulsion. The methanol extract of PS exhibited high antioxidative activity that was not significantly (P < 0.05) different from α-tocopherol, while aqueous extracts of PS showed low antioxidative activity. Similar trends of antioxidant activity were observed using either the FTC or TBA methods. Antioxidant activity, reducing power, free radical scavenging (DPPH·), superoxide anion radical scavenging, metal chelating and hydrogen peroxide scavenging activities of PS extracts showed dose dependence and increased with concentration of PS extract. The results obtained in the present study indicate that the PS might be a potential source of natural antioxidant.

Anti-oxidant and anti-inflammatory activities of leaves of Barringtonia racemosa

The medicinal plant of Barringtonia racemosa (lecythidaceae family) has been used widely in traditional medicine for anti-inflammation and anticancer in Malaysia. The present investigation was carried out to study of the anti-oxidant and anti-inflammatory effects of fully expanded leaf extracts of B. racemosa. Antioxidant activity was measured by using FTC, TBA and DPPH free radical scavenging methods and Griess assay was also used for the measurement of nitric oxide inhibition in lipopolysaccharide (LPS) and interferon- ×¢ (IFN- ×¢)-treated RAW 264.7 cells. Different crude extracts of fully expanded leaf extracts of B. racemosa have exhibited a very good level of nitric oxide (NO) inhibitory and antioxidant activities. In the Griess assay, non polar extracts such as chloroform and hexane extracts were found to be strong inhibitors of NO at different concentrations (25, 50, 100 and 200 µg/ml) in comparison with polar extract (ethanol extract). Chloroform extract didn’t show cytotoxicity against RAW 264.7 cells at different concentrations contrary to hexane and ethanol extracts. The chloroform and hexane extracts exhibited very strong antioxidant properties when compared to Vitamin E (a-tocopherol) in the FTC and TBA methods, the chloroform and hexane extracts exhibited the radical scavenging activity with an IC50 value of 54.29 and 63 µg/ml respectively. Results demonstrated that chloroform extract of B. racemosa leaf may have the potential to be used as anti-inflammation and anti-oxidant agents and it was revealed that the active compound in B. racemosa is lycopene. Key words: Barringtonia racemosa, anti-oxidant, anti-inflammatory.

Evaluation of antioxidant and nitric oxide inhibitory activities of selected Malaysian medicinal plants

Methanol extracts of seven Malaysian medicinal plants were screened for antioxidant and nitric oxide inhibitory activities. Antioxidant activity was measured by using FTC, TBA and DPPH free radical scavenging methods and Griess assay was used for the measurement of nitric oxide inhibition in lipopolysaccharide (LPS) and interferon-γ (IFN-γ)-treated RAW 264.7 cells. All the extracts showed strong antioxidant activity comparable to or higher than that of α-tocopherol, BHT and quercetin in FTC and TBA methods. The extracts from Leea indica and Spermacoce articularis showed strong DPPH free radical scavenging activity comparable with quercetin, BHT and Vit C. Spermacoce exilis showed only moderate activity but other species were weak as compared to the standards. In the Griess assay Lasianthus oblongus, Chasalia chartacea, Hedyotis verticillata, Spermacoce articularis and Leea indica showed strong inhibitory activity on nitric oxide production in LPS and IFN-γ-induced RAW 264.7 cells. Extracts from Psychotria rostrata and Spermacoce exilis also inhibited NO production but this was due to their cytotoxic effects upon cells during culture.

Antioxidative activity of extracts from Mengkudu ( Morinda citrifolia L.) root, fruit and leaf

This study was conducted to evaluate the antioxidative activity of extracts from different parts of Mengkudu ( Morinda citrifolia L.), including leaf, fruit and root. Methanol and ethyl acetate were used as solvents and antioxidative effects measured by a ferric thiocyanate method (FTC) and thiobarbituric acid test (TBA). The methanol extract of Mengkudu root exhibited high antioxidative activity that was not significantly ( P<0.05) different from α-tocopherol or butylated hydroxyl toluene (BHT), while the methanol extracts of fruit and leaf showed negligible activities. On the other hand, the ethyl acetate extract of all parts of Mengkudu exhibited significant antioxidative activity, which is comparable to that of both α-tocopherol and BHT. Similar trends of antioxidant activity were observed using either the FTC or TBA methods. Roots showed the highest activity of the parts tested. The results suggest that several compounds contribute to antioxidative activity of different parts of Mengkudu. Activity in the roots may be due to both polar and non-polar compounds but, in the leaf and fruit, only to non-polar compounds.