PRELIMINARY RESEARCH REGARDING THE THERAPEUTIC USES OF URTICA DIOICA L. NOTE I. THE POLYPHENOLS EVALUATION
The use of stinging nettle leaves for the treatment of diabetes mellitus without a scientific evaluation, persuaded us to study them, in order to obtain pharmacological active extracts. According to scientific data, polyphenols are known as HMG-CoA reductase inhibitors and have potent anti-glycation activity. These compounds are the main active principles in the Urticae folium. The aim of this study was to evaluate the polyphenols’content (polyphenolcarboxilic acids = PPCA, and flavonoids) of stinging nettle leaves, harvested from culture and wild flora, originated from Racari, Dambovita district, Romania. Spectrophotometric and chromatographic methods were used. A new HPLC method for the identification and quantification of caffeic and chlorogenic acids from Urticae folium was also developed. The highest contents of polyphenolcarboxilic acids (expressed as % of chlorogenic acid) and flavonoids (expressed as % of rutin) were found in the leaves of wild nettles harvested in the month of March (4.2295% chlorogenic acid and 0.6237% rutin). The polyphenols’ content is slightly lower than the ones mentioned in the scientific literature. The content of PPCA decreases from March till September, both in wild and cultivated samples. The variation of the flavonoids’content differs with the origin of raw material (culture or spontaneus flora). The new HPLC method for polyphenols’analysis is reproductible. Rezumat Utilizarea tradiţională a produsului Urticae folium in diabet, fără o justificare stiintifica a acţiunii precum si menţionarea flavonelor si acizilor fenolcarboxilici (compusii majoritari) ca inhibitori ai HMG-CoA reductazei si ai proceselor de glicozilare si lipoxidare avansată, ne‐au determinat să abordăm cercetarea acestora, in vederea valorificării terapeutice sub formă de extracte selective. In acest scop am derulat o cercetare spectrofotometrică si cromatografică (HPLC) pentru a pune in evidenţă polifenolii prezenţi in frunzele de urzică recoltate din flora spontană si de cultură, din localitatea Răcari, judeţul Dâmboviţa. De asemenea, ne-am propus să separăm acizii cafeic si clorogenic si să-i determinăm cantitativ printr-o nouă metodă HPLC/UV.
Chemical composition of celandine (Chelidonium majus L.) extract and its effects on Botrytis tulipae (Lib.) Lind fungus and the tulip.
In this study, the content of chelidonine and berberine alkaloids, and sterols and phenols in the Chelidonium majus plant extract were analyzed. Subsequently, the effects of the extract on the germination and growth of Botrytis tulipae fungus on nutritive medium were compared to the effects of fluconazole. The plant extract was used at the minimum inhibitory concentration on B. tulipae developed in tulip leaves and the in vivo effects were investigated. The influence of different concentrations of C. majus extract on the physiological processes of the tulip (gas exchange parameters, photosynthetic light use efficiency, and induced chlorophyll fluorescence) were also tested to assess the applicability of the extract for the protection of ornamental plants against fungal infection. Our results demonstrated that 2% celandine extract does not significantly change the gas exchange parameters (transpiration rate, carbon dioxide uptake, and stomatal conductivity) of leaves exposed for 2 h, and does not interfere with the photochemical processes in the leaves. However, in higher concentrations, it increases the transpiration rate and net carbon dioxide influx. At concentrations of 15% and 20%, the extract lowers the potential quantum yield efficiency of photosystem II and the vitality index of the photosynthetic apparatus. Therefore we recommend the use of lower concentrations (â‰¤6%) of celandine extract for the biological protection of tulips against gray mold.
Computer-Aided System of Virtual Testing of Gas Turbine Engines
The article describes the concept of a virtual lab that includes subsystem of gas turbine engine simulation, subsystem of experiment planning, subsystem of measurement errors simulation, subsystem of simulator identification and others. The basis for virtual lab development is the computer-aided system of thermogasdynamic research and analysis “ASTRA”. The features of gas turbine engine transient modes simulator are described. The principal difference between the simulators of transient and stationary modes of gas turbine engines is that the energy balance of the compressor and turbine becomes not applicable. The computer-aided system of virtual gas turbine engine testing was created using the developed transient modes simulator. This system solves the tasks of operational (throttling, speed, climatic, altitude) characteristics calculation, analysis of transient dynamics and selection of optimal control laws. Besides, the system of virtual gas turbine engine testing is a clear demonstration of gas turbine engine working process and the regularities of engine elements collaboration. The interface of the system of virtual gas turbine engine testing is described in the article and some screenshots of the interface elements are provided. The developed system of virtual gas turbine engine testing provides means for reducing the laboriousness of gas turbine engines testing. Besides, the implementation of this system in the learning process allows the diversification of lab works and therefore improve the quality of training.