Search results for "S1"
showing 10 items of 755 documents
Development of high-performance thin layer chromatography method for identification of phenolic compounds and quantification of rosmarinic acid conte…
2020
ABSTRACT Aim: Representatives of Nepetoideae Burnett subfamily are promising species of the Lamiaceae Martinov family because of accumulating such valuable groups of secondary metabolites as terpenoids and polyphenols. A high-performance thin layer chromatography (HPTLC) fingerprint method for the qualitative determination of phenolic compounds and for the quantification of rosmarinic acid (RA) content in methanol extracts of five species of this subfamily was developed for the first time. Materials and Methods: Dried aerial parts of Dracocephalum moldavica L., Ocimum americanum L., Lophanthus anisatus (Nutt.) Benth., Monarda fistulosa L., and Satureja hortensis L. collected in flowering pe…
Perceptions of university students about their education in physics in secondary education
2018
Este artículo presenta los resultados de un cuestionario diagnóstico sobre las percepciones hacia la física, por parte de 104 estudiantes, quienes inician su carrera profesional de Licenciatura en Ciencias Naturales y Educación Ambiental, en una universidad colombiana. Este estudio, se centró en las siguientes categorías: experiencias sobre el aprendizaje de la física, metodología del profesor en la clase de física, dificultades de los estudiantes para aprender física y sugerencias para mejorar su enseñanza. Los resultados reflejan la importancia de explorar y generar estrategias, que permitan optimizar las cuatro dimensiones; por ejemplo, en relación al aprendizaje de la física, los partic…
ESTIMATING SOIL PARTICLE-SIZE DISTRIBUTION FOR SICILIAN SOILS
2009
The soil particle-size distribution (PSD) is commonly used for soil classification and for estimating soil behavior. An accurate mathematical representation of the PSD is required to estimate soil hydraulic properties and to compare texture measurements from different classification systems. The objective of this study was to evaluate the ability of the Haverkamp and Parlange (HP) and Fredlund et al. (F) PSD models to fit 243 measured PSDs from a wide range of 38 005_Bagarello(547)_33 18-11-2009 11:55 Pagina 38 soil textures in Sicily and to test the effect of the number of measured particle diameters on the fitting of the theoretical PSD. For each soil textural class, the best fitting perf…
Microneedle-Based Delivery: An Overview of Current Applications and Trends
2020
Microneedle arrays (MNA) are considered as one of the most promising resources to achieve systemic effects by transdermal delivery of drugs. They are designed as a minimally invasive, painless system which can bypass the stratum corneum, overcoming the potential drawbacks of subcutaneous injections and other transdermal delivery systems such as chemical enhancers, nano and microparticles, or physical treatments. As a trendy field in pharmaceutical and biomedical research, its applications are constantly evolving, even though they are based on very well-established techniques. The number of molecules administered by MNA are also increasing, with insulin and vaccines administration being the …
Domini collettivi, forme di autogoverno per la gestione degli ecosistemi e lo sviluppo locale
2020
One of the most ancient forms of self-government of environmental systems is that relating to the management of civic uses and collective lands, in which a specific local community controls and manages sustainable resources (fields, pastures, woods, etc.) sustainably and efficiently. The paper aims to briefly retrace the salient stages of the history of collective domains, and to explore their value as “goods that are produced by long co-evolutionary processes between human settlement and environment” (Magnaghi 2015, 139) highlighting the appearance of complex socio-ecological systems (SES). Finally, using the theory developed by Elinor Ostrom to analyze the sustainability of SES (Ostrom 20…
A simple field method to measure the hydrodynamic properties of soil surface crust
2013
The hydraulic resistance of the surface crust was determined by a combination of two infiltrometric techniques: first, a surface measurement of steady-state infiltration rate is conducted by a mini-disk tension infiltrometer (MDI); then, the surface crust is removed, its thickness is measured, and a ponded infiltration test is performed at the same site. The Beerkan Estimation of Soil Transfer parameters (BEST) method is applied to estimate the hydraulic properties of the underlying soil provided the particlesize distribution and the bulk density are known. Under the assumption of a unit gradient of hydraulic head below the soil crust, the pressure head at the interface crust-soil is derive…
Combined Use of Structure Analysis, Studies of Molecular Association in Solution, and Molecular Modelling to Understand the Different Propensities of…
2021
The arrangement of hydroxyl groups in the benzene ring has a significant effect on the propensity of dihydroxybenzoic acids (diOHBAs) to form different solid phases when crystallized from solution. All six diOHBAs were categorized into distinctive groups according to the solid phases obtained when crystallized from selected solvents. A combined study using crystal structure and molecule electrostatic potential surface analysis, as well as an exploration of molecular association in solution using spectroscopic methods and molecular dynamics simulations were used to determine the possible mechanism of how the location of the phenolic hydroxyl groups affect the diversity of solid phases formed…
Advances in Nanoliposomes Production for Ferrous Sulfate Delivery
2020
In this study, a continuous bench scale apparatus based on microfluidic fluid dynamic principles was used in the production of ferrous sulfate-nanoliposomes for pharmaceutical/nutraceutical applications, optimizing their formulation with respect to the products already present on the market. After an evaluation of its fluid dynamic nature, the simil-microfluidic (SMF) apparatus was first used to study the effects of the adopted process parameters on vesicles dimensional features by using ultrasonic energy to enhance liposomes homogenization. Subsequently, iron-nanoliposomes were produced at different weight ratios of ferrous sulfate to the total formulation components (0.06, 0.035, 0.02, an…
Hloramfenikola selektīvā spiediena ietekme uz acetiltransferāzes gēna aktivēšanu pAdCat plazmīdā Escherichi coli kultūras stacionārā fāzē
2015
IS10 ir viens no aktīvākajiem transpozoniem, kas nodrošina adapatīvo mutaģenēzi baktērijām, aktivizējot neekspresējošus gēnus. Darba mērķis bija noskaidrot hloramfenikola selektīvā spiediena ietekmi uz IS10 elementa spēju efektīvāk aktivizēt bezpromotera acetiltransferāzes (cat) gēnu pAdCat plazmīdā Escherichia coli kultūras stacionārā augšanas fāzē. Baktēriju celmi tika transformēti ar pAdCat plazmīdu, kas kalpo par vektoru-lamatu IS10 elementu izolēšanai pēc pozitīvās selekcijas principa. Šūnām, atrodoties trīs dienas stacionārajā fāzē, novēroja IS10 transpozīciju un bezpromotera hloramfenikola acetiltransferāzes (cat) gēna aktivizēšanu. Gēna aktivizēšanu nodrošināja gan IS10R, gan IS10H.…
Stability of stochastic nonlinear systems with state-dependent switching
2013
In this paper, the problem of stability on stochastic systems with state-dependent switching is investigated. To analyze properties of the switched system by means of Itô’s formula and Dynkin’s formula, it is critical to show switching instants being stopping times. When the given active-region set can be replaced by its interior, the local solution of the switched system is constructed by defining a series of stopping times as switching instants, and the criteria on global existence and stability of solution are presented by Lyapunov approach. For the case where the active-region set can not be replaced by its interior, the switched systems do not necessarily have solutions, thereby quasi-…