Study on chemical constituents of the lichen Parmotrema sancti-angelii (Lynge) Hale. (Parmeliaceae)

Lichens are fungal and algal/cyanobacterial symbioses resulting in the production of specific metabolites. Parmotrema sancti-angelii (Lynge) Hale is a lichen which has not been chemically and biologically studied well. From the lichen collected in Vietnam, colour reactions for identification of lichen substances (+K  red, +P yellow, -C, +KC red ) suggested the presence of quinones, depsides and xanthones containing two free hydroxyl groups in meta-position, depsides and depsidones containing an aldehyde group. Chemical constituent study led to the isolation of three compounds, including methyl β-orcinolcarboxylate (1), salazinic acid (2) and atranorin (3). Their structures were confirmed unambiguously by X-ray diffraction, spectroscopic data and compared with those in references. This is the first report of salazinic acid distribution in such lichen. Keywords. Parmeliaceae, Parmotrema sancti-angelii, X-ray, NMR, salazinic acid

Control Voltage Effect on Operational Characteristics of Vehicle Magnetorheological Damper

Considering the increasingly large-scale application of magnetic fluids in various industries, we can confidently state that in the near future magnetorheological dampers will be widely used in adaptive automotive suspensions due to their operational flexibility and simplicity of controlling damping forces by changing the magnetic fluid properties according to parameters of surrounding electromagnetic field. The antivibration efficiency during operation is achieved by regulating the hydraulic resistance of the “magnetic” shock absorber by applying voltage to the windings of its coil. In addition to the physical properties of the oil used in the “magnetic” shock absorber, the viscosity of the working magnetorheological fluid is greatly influenced by the shape of the control signal. The paper focuses on the theoretical aspects of constructing a mathematical model of ac magnetorheological damper and presents the results of a computer experiment to assess effectiveness of its use as part of the adaptive suspension a passenger vehicle. In this case, the actual parameters of the “magnetic” shock absorber, used in modeling the dynamic process, were determined experimentally on a test bench, and the adequacy of the developed mathematical model was confirmed by the results of a semi-natural experiment. Using a verified model, the magnetorheological damper characteristics were obtained and compared for various forms of control signal, including rectangular voltage pulses of various frequencies and duty cycles, sinusoidal pulses and constant voltage signals. The analysis of the antivibration efficiency was carried out on the basis of the developed “quarter” model of a semi-active car suspension with a verified submodel of a magnetorheological damper integrated into its structure. Moreover, the simulation scenarios were based on the selected strategy for controlling the voltage supplied to the windings of the “magnetic” shock absorber. As the results of theoretical and experimental studies have shown in terms of energy consumption, expansion of the working area of the damping characteristic and achieving smooth control of the damping force, the most effective is the use of a sinusoidal pulse voltage signal in the control circuit, which ensures a reduction in both the amplitude and damping time of oscillations. However, when de-signing and manufacturing a controller, creating a pulse modulator for generating sinusoidal pulses coinciding in phase and frequency with the vibrations of the car body is very difficult due to the random nature of external disturbances from the road surface. When a constant voltage is applied to the magnetorheological damper winding, the damping properties of the suspension are also improved compared to the basic design based on a traditional hydraulic shock absorber. Moreover, there is a proportional relationship between the voltage supplying the damper, the amplitude and damping time of the vibrations of the car body is observed. An increase in the control signal voltage from 1 to 2 V leads, in comparison with passive control of a magnetic shock absorber, to a decrease in the maximum amplitude of vibrations of the car body by 6.25 and 11.25 %, respectively, and a decrease in the vibration damping time by 0.72 and 1.41 s

Research of Regenerative Braking Strategy for Electric Vehicles

In the context of global energy instability caused by the transformation of global demand for energy and energy resources, one of the most important areas in the automotive industry is the development of electric vehicles. Serial production of high-tech electric vehicles with a long range contributes to the stabilization of the energy market and the sustainable development of the whole fuel-energy sector. To evaluate the possibility of optimizing the electric vehicles energy consumption, various regenerative braking strategies are discussed in the article based on the Nissan Leaf electric vehicle, which simulation model includes submodules of the traction electric motor, hybrid braking system, traction rechargeable battery and tires. In order to test the adequacy of the simulation model to reproduce the relationship between the operating parameters of electric vehicles various systems and evaluate their ability to regenerate energy during braking the simulation results were compared with the actual experimental data published by the Lab Avt research laboratory (USA). The relative error of the mathematical modeling results of the braking energy regeneration processes is 4.5 %, which indicates the adequacy of the electric vehicle simulation model and the possibility of its using as a base for research and comparison of the energy efficiency of various regenerative braking strategies. As the results of experiments have shown, the usage of the proposed control strategy of the regenerative braking maximum force allows increasing 2.14 times the energy recharging traffic to the battery as compared with the basic control strategy of fixed coefficient braking forces distribution with an increase in braking distance by 10 m. An alternative control strategy of regenerative braking optimal efficiency as compared to the basic control strategy provides a reduction in braking distance by 13.2 % at increasing by 84.4 % the amount of energy generated by the electric motor for recharging the batteries. The carried out investigations confirm the available significant potential for improving the efficiency of the electric vehicles usage by developing the control strategy and algorithms of the braking energy regeneration

Исследование стратегии рекуперативного торможения электромобилей

In the context of global energy instability caused by the transformation of global demand for energy and energy resources, one of the most important areas in the automotive industry is the development of electric vehicles. Serial production of high-tech electric vehicles with a long range contributes to the stabilization of the energy market and the sustainable development of the whole fuel-energy sector. To evaluate the possibility of optimizing the electric vehicles energy consumption, various regenerative braking strategies are discussed in the article based on the Nissan Leaf electric vehicle, which simulation model includes submodules of the traction electric motor, hybrid braking system, traction rechargeable battery and tires. In order to test the adequacy of the simulation model to reproduce the relationship between the operating parameters of electric vehicles various systems and evaluate their ability to regenerate energy during braking the simulation results were compared with the actual experimental data published by the Lab Avt research laboratory (USA). The relative error of the mathematical modeling results of the braking energy regeneration processes is 4.5 %, which indicates the adequacy of the electric vehicle simulation model and the possibility of its using as a base for research and comparison of the energy efficiency of various regenerative braking strategies. As the results of experiments have shown, the usage of the proposed control strategy of the regenerative braking maximum force allows increasing 2.14 times the energy recharging traffic to the battery as compared with the basic control strategy of fixed coefficient braking forces distribution with an increase in braking distance by 10 m. An alternative control strategy of regenerative braking optimal efficiency as compared to the basic control strategy provides a reduction in braking distance by 13.2 % at increasing by 84.4 % the amount of energy generated by the electric motor for recharging the batteries. The carried out investigations confirm the available significant potential for improving the efficiency of the electric vehicles usage by developing the control strategy and algorithms of the braking energy regeneration.В условиях энергетической нестабильности, вызванной трансформацией глобального спроса на энергию и энергоресурсы, одним из важнейших направлений в автомобилестроении является разработка транспортных средств на электрической тяге. Серийное производство высокотехнологичных электромобилей с большим запасом хода способствует стабилизации рынка энергоресурсов и устойчивому развитию всего топливно-энергетического сектора. Для оценки возможности оптимизации энергопотребления электромобилей в статье рассматриваются различные стратегии рекуперативного торможения на базе имитационной модели электромобиля Nissan Leaf, включающей субмодули тягового электродвигателя, гибридной тормозной системы, тяговой аккумуляторной батареи и шин. Результаты моделирования сопоставлялись с экспериментальными данными научно-исследовательской лаборатории Lab Avt (США), опубликованными для проверки адекватности имитационных моделей, воспроизводящих взаимосвязь между рабочими параметрами различных систем электромобиля и оценивающих их способность регенерировать энергию при торможении. Относительная погрешность результатов математического моделирования процессов рекуперации энергии составляет 4,5 %, что свидетельствует об адекватности имитационной модели электромобиля и возможности ее использования в качестве базовой для исследований и сопоставления энергоэффективности различных стратегий рекуперативного торможения. Как показали результаты экспериментов, использование предлагаемой стратегии управления максимальной силой рекуперативного торможения позволяет увеличить трафик энергии подзарядки в 2,14 раза по сравнению с базовой стратегией управления на основе фиксированного коэффициента распределения тормозных усилий по осям транспортного средства при увеличении тормозного пути на 10 м. Альтернативная стратегия управления оптимальной эффективностью рекуперативного торможения обеспечивает по сравнению с базовой стратегией уменьшение тормозного пути на 13,2 % при одновременном увеличении на 84,4 % количества вырабатываемой электродвигателем энергии для подзарядки тяговых аккумуляторных батарей. Проведенные исследования подтверждают имеющийся потенциал по повышению эффективности использования электромобилей за счет совершенствования стратегии и алгоритмов управления рекуперацией энергии торможения

Phytochemical studies of plants used in traditional medicines of Vietnam and Laos. Biological evaluation in therapeutic domain.

L’objectif de ce travail est de contribuer à l'amélioration des connaissances phytochimiques et biologiques des plantes medicinales, afin d’en valoriser et d’en promouvoir l'usage en médicine traditionnelle au Vietnam. Dans ce travail de thèse, nous avons mené une étude phytochimique sur trois espèces végétales: Cleome chelidonii (Cleomaceae), Dolichandrone spathacea (Bignoniaceae) et Flacourtia rukam (Salicaceae). 90 composés ont été isolés et leurs structures ont été déterminées à l’aide des techniques spectroscopiques de RMN 1D et 2D, par la spectrométrie de masse ESI-MS, des données spectrales en UV, IR, la mesure du pouvoir rotatoire et des courbes de CD, et par comparaison avec les données de la littérature. Parmi ces composés, 29 correspondent à des molécules nouvellement décrites. Les composés isolés peuvent être classés en plusieurs groupes : flavonoïdes, iridoides, saponosides, mégastigmanes, glycosides phénoliques, alcaloïdes, …L’évaluation de l’activité anti-radicalaire (test DPPH) a été effectuée sur les flavonoides de C. chelidonii, et les activités antimicrobiennes des extraits et composés de D. spathacea et F. rukam ont été mesurées. Parmi les composés testés, le glycoside de quercétol nouveau CF-3 est le seul à posséder une activité anti-radicalaire importante (CI50 = 17,74 µM) et le glucoside phénolique nouveau FRP-4 possède l’activité antibactérienne la plus importante contre trois bactéries à Gram positif (CMI = 31,2 µg/ml) et deux bactéries à Gram négatif (CMI = 125 µg/ml).The objective of this work is to contribute to the improvement of phytochemical and biological knowledge of medicinal plants, in order to enhance and promote their uses in traditional medicine in Vietnam. In this thesis, we carried out a phytochemical study on three plants: Cleome chelidonii (Cleomaceae) Dolichandrone spathacea (Bignoniaceae) and Flacourtia rukam (Salicaceae). 90 compounds were isolated and their structures were determinated using the spectroscopic techniques of 1D & 2D NMR and by the ESI-MS mass spectrometry, spectral data UV, IR, measurement of optical rotation and CD, and by comparison with the literature data. Among them, 29 are new molecules. The isolated compounds may be classified into many groups: flavonoids, iridoids, saponins, megastigmanes, phenolic glycosides, alkaloids...The antiradical activity of the flavonoids of C. Chelidonii was evaluated by the DPPH test, and the antimicrobial activity were examinated on all extracts and compounds of D. spathacea and F. rukam. Among the tested compounds, the new flavonoid CF-3 has a significant anti-radical activity (IC50 = 17.74 µM) and the new phenolic glucoside FRP-4 has the most significant antibacterial activity against three Gram-positive bacteria (MIC = 31.2 µg / ml) and two gram-negative bacteria (MIC = 125 µg /ml)

Developmental Toxicity of Clerodendrum cyrtophyllum Turcz Ethanol Extract in Zebrafish Embryo

ETHNOPHARMACOLOGICAL RELEVANCE: Clerodendrum cyrtophyllum Turcz has been used in traditional medicine for the treatment of various diseases. In spite of its therapeutic applications, research on its toxicity and teratogenicity is still limited. AIM OF THE STUDY: The study aimed to investigate the developmental toxicity of the ethanol extract of C. cyrtophyllum (EE) in zebrafish embryo model. MATERIAL AND METHODS: Major compounds from crude ethanol extract of Clerodendron cyrtophyllum Turcz leaves were determined using HPLC-DAD-Orbitrap-MS analysis. The developmental toxicity of EE were investigated using zebrafish embryo model. Zebrafish embryos at 6 h post-fertilization (hpf) were treated with EE at different concentrations. Egg coagulation, mortality, hatching, yolk sac oedema, pericardial oedema and teratogenicity were recorded each day for during a 5-day exposure. At time point 120 hpf, body length, pericardial area, heartbeat and yolk sac area were assessed. In order to elucidate molecular mechanisms for the developmental toxicity of EE, we further evaluated the effects of the EE on the expression of genes involved on signaling pathways affecting fish embryo's development such as heart development (gata5, myl7, myh6, has2, hand2, nkx 2.5), oxidative stress (cat, sod1, gpx4, gstp2), wnt pathway (beta-catenin, wnt3a, wnt5, wnt8a, wnt11), or cell apoptosis (p53, bax, bcl2, casp3, casp8, casp9, apaf-1, gadd45bb) using qRT-PCR analysis. RESULTS: Our results demonstrated that three major components including acteoside, cirsilineol and cirsilineol-4'-O-beta-D-glucopyranoside were identified from EE. EE exposure during 6- 96 h post-fertilization (hpf) at doses ranging from 80 - 200 mug/ml increased embryo mortality and reduced hatching rate. EE exposure at 20 and 40 mug/ml until 72 - 120 hpf induced a series of malformations, including yolk sac oedema, pericardial oedema, spine deformation, shorter body length. Based on two prediction models using a teratogenic index (TI), a 25% lethality concentration (LD25) and the no observed-adverse-effect level (NOAEL), EE is considered as teratogenic for zebrafish embryos with TI (LC50/EC50) and LD25/NOAEC values at 96 hpf reaching 3.87 and 15.73 respectively. The mRNA expression levels of p53, casp8, bax/bcl2, gstp2, nkx2.5, wnt3a, wnt11, gadd45bb and gata5 were significantly upregulated by EE exposure at 20 and 40 mug/ml while the expression of wnt5, hand2 and bcl2 were downregulated. CONCLUSIONS: These results provide evidence for toxicity effects of EE to embryo stages and provide an insight into the potential toxicity mechanisms on embryonic development

Developmental Toxicity of Clerodendrum cyrtophyllum Turcz Ethanol Extract in Zebrafish Embryo

ETHNOPHARMACOLOGICAL RELEVANCE: Clerodendrum cyrtophyllum Turcz has been used in traditional medicine for the treatment of various diseases. In spite of its therapeutic applications, research on its toxicity and teratogenicity is still limited. AIM OF THE STUDY: The study aimed to investigate the developmental toxicity of the ethanol extract of C. cyrtophyllum (EE) in zebrafish embryo model. MATERIAL AND METHODS: Major compounds from crude ethanol extract of Clerodendron cyrtophyllum Turcz leaves were determined using HPLC-DAD-Orbitrap-MS analysis. The developmental toxicity of EE were investigated using zebrafish embryo model. Zebrafish embryos at 6 h post-fertilization (hpf) were treated with EE at different concentrations. Egg coagulation, mortality, hatching, yolk sac oedema, pericardial oedema and teratogenicity were recorded each day for during a 5-day exposure. At time point 120 hpf, body length, pericardial area, heartbeat and yolk sac area were assessed. In order to elucidate molecular mechanisms for the developmental toxicity of EE, we further evaluated the effects of the EE on the expression of genes involved on signaling pathways affecting fish embryo's development such as heart development (gata5, myl7, myh6, has2, hand2, nkx 2.5), oxidative stress (cat, sod1, gpx4, gstp2), wnt pathway (β-catenin, wnt3a, wnt5, wnt8a, wnt11), or cell apoptosis (p53, bax, bcl2, casp3, casp8, casp9, apaf-1, gadd45bb) using qRT-PCR analysis. RESULTS: Our results demonstrated that three major components including acteoside, cirsilineol and cirsilineol-4'-O-β-D-glucopyranoside were identified from EE. EE exposure during 6- 96 h post-fertilization (hpf) at doses ranging from 80 - 200 μg/ml increased embryo mortality and reduced hatching rate. EE exposure at 20 and 40 μg/ml until 72 - 120 hpf induced a series of malformations, including yolk sac oedema, pericardial oedema, spine deformation, shorter body length. Based on two prediction models using a teratogenic index (TI), a 25% lethality concentration (LD25) and the no observed-adverse-effect level (NOAEL), EE is considered as teratogenic for zebrafish embryos with TI (LC50/EC50) and LD25/NOAEC values at 96 hpf reaching 3.87 and 15.73 respectively. The mRNA expression levels of p53, casp8, bax/bcl2, gstp2, nkx2.5, wnt3a, wnt11, gadd45bb and gata5 were significantly upregulated by EE exposure at 20 and 40 μg/ml while the expression of wnt5, hand2 and bcl2 were downregulated. CONCLUSIONS: These results provide evidence for toxicity effects of EE to embryo stages and provide an insight into the potential toxicity mechanisms on embryonic development

Three New Iridoid Glueoside Salts from Hedyotis tenelliflora Growing in Vietnam

status: publishe