Search results for "solution"
showing 10 items of 5638 documents
Enthalpies of solution and dilution of butanol and pentanol in dodecyltrimethylammonium bromide micellar solutions
1987
The enthalpies of solution and of dilution of 1-butanol and 1-pentanol were measured in micellar solutions of dodecyltrimethylammonium bromide by systematically changing the concentration of alcohols and surfactant. The enthalpies of solution at infinite dilution of alcohols at each surfactant concentration were evaluated from a linear plot. This quantity increases with surfactant concentration (up to 0.8m) with a curvature which depends on the alcohol alkyl chain length. The difficulties arising for a quantitative treatment of both the enthalpies of dilution and of solution at finite alcohol concentrations are discussed. The dependence on the surfactant concentration of the standard enthal…
A third order partial differential equation for isotropic boundary based triangular Bézier surface generation
2011
Abstract We approach surface design by solving a linear third order Partial Differential Equation (PDE). We present an explicit polynomial solution method for triangular Bezier PDE surface generation characterized by a boundary configuration. The third order PDE comes from a symmetric operator defined here to overcome the anisotropy drawback of any operator over triangular Bezier surfaces.
Explicit Bézier control net of a PDE surface
2017
The PDE under study here is a general fourth-order linear elliptic Partial Differential Equation. Having prescribed the boundary control points, we provide the explicit expression of the whole control net of the associated PDE Bézier surface. In other words, we obtain the explicit expressions of the interior control points as linear combinations of free boundary control points. The set of scalar coefficients of these combinations works like a mould for PDE surfaces. Thus, once this mould has been computed for a given degree, real-time manipulation of the resulting surfaces becomes possible by modifying the prescribed information. The work was partially supported by Spanish Ministry of Econo…
MILES extended: Stellar population synthesis models from the optical to the infrared
2016
We present the first single-burst stellar population models which covers the optical and the infrared wavelength range between 3500 and 50000 Angstrom and which are exclusively based on empirical stellar spectra. To obtain these joint models, we combined the extended MILES models in the optical with our new infrared models that are based on the IRTF (Infrared Telescope Facility) library. The latter are available only for a limited range in terms of both age and metallicity. Our combined single-burst stellar population models were calculated for ages larger than 1 Gyr, for metallicities between [Fe/H] = -0.40 and 0.26, for initial mass functions of various types and slopes, and on the basis …
Chemical Identification at the Solid–Liquid Interface
2017
Solid-liquid interfaces are decisive for a wide range of natural and technological processes, including fields as diverse as geochemistry and environmental science as well as catalysis and corrosion protection. Dynamic atomic force microscopy nowadays provides unparalleled structural insights into solid-liquid interfaces, including the solvation structure above the surface. In contrast, chemical identification of individual interfacial atoms still remains a considerable challenge. So far, an identification of chemically alike atoms in a surface alloy has only been demonstrated under well-controlled ultrahigh vacuum conditions. In liquids, the recent advent of three-dimensional force mapping…
Drivers of peat accumulation rate in a raised bog: impact of drainage, climate, and local vegetation composition
2017
We used variation partitioning to assess the relative importance of drainage, climate and local vegetation composition for the development of a raised bog. As a case study we selected Teici (Teici) Bog in Latvia (north-east Europe). Explanatory variables together explained 74 % of the variation in peat accumulation and only the residue of 26 % remained unexplained. Our study showed that the local vegetation composition and dominant Sphagnum species significantly influence peat accumulation rates. The results of linear models revealed that, under natural conditions, minor drainage and even strong drainage of the peat is associated with a positive growth balance of the system. However, draina…
Effect of temperature on the passive state of Alloy 31 in a LiBr solution: Passivation and Mott-Schottky analysis
2015
The passive behaviour of Alloy 31, a highly-alloyed austenitic stainless steel (UNS N08031), has been investigated in a LiBr heavy brine (700 g/l) at different temperatures using potentiostatic polarisation and Mott-Schottky analysis. Cation vacancies have been found to be the dominant defect in the passive films formed on Alloy 31. An increase in temperature enhanced the generation of cation vacancies at the film/solution interface and raised the steady-state passive current density. The density of defects within the passive film also increased significantly with temperature, making the film more conductive and less protective against localised attacks.
Tetrazola hemiamināls kā hirāla palīggrupa
2017
Tetrazola hemiamināls kā hirāla palīggrupa. Sējējs M., zinātniskais vadītājs Prof., Dr. chem. Sūna E., konsultēja MSc. chem., Kinēns A. Maģistra darbs uzrakstīts latviešu valodā, tā apjoms 58 lapaspuses. Darbs satur 56 attēlus, 5 tabulas. Maģistra darbs veltīts terazolu hemiaminālu hirālās palīggrupas iegūšanai un pielietojumam diastereoselektīvajā sintēzē. Izstrādātās hirālās palīggrupas efektivitāte demonstrēta, ar augstu diastereoselektivitāti veicot karbonskābju α-pozīcijas fluorēšanas un nitrozo-aldola reakcijas. Darba rezultātā izstrādāts tetrazola hemiamināla hirālās palīggrupas stereoindukcijas modelis. Demonstrēta hirālās palīggrupas šķelšana maigos reakcijas apstākļos. Tetrazola h…
Effect of stiffness on the phase behavior of cubic lattice chains
2005
Gran canonica Monte Carlo (GCMC) simulazioni assistite da tecniche di riponderazione istogramma sono stati utilizzati per studiare l'effetto della flessibilità catena sul comportamento di soluzione fase di cubi catene reticolari corti con 4-32 segmenti. Ciò è stato fatto variando un parametro di rigidità gradualmente fino alla media calcolata end-to-end distanza avvicinato la lunghezza totale. Per entrambe le catene flessibili e rigide si è riscontrato che la temperatura critica, ottenuta tramite mista analisi dei campi di dimensioni finite, aumentata lunghezza della catena e la densità critica trasferisce a valori più bassi, in accordo con le osservazioni sperimentali. Il estrapolato lungh…
A multifuctional nanoplatform for drug targeted delivery based on radiation-engineered nanogels
2020
Abstract Under a rational design, combining biologically active molecules, ligands to specific cell receptors and fluorescent, radioactive or paramagnetic labels into a single nano-object can bridge the unique properties of the individual components and improve conventional sensing, imaging and therapeutic efficacies. The validation of these functional nano-objects requires careful testing both in terms of physico-chemical properties and biological behaviour in vitro and in vivo, prior to translation into the clinic. Ionising radiation of aqueous polymer solutions is a viable strategy to produce multifunctional nanogels from aqueous solutions of hydrophilic polymers. By proper selection of …