Search results for " solution"
showing 10 items of 3084 documents
Apparent molar volumes of 1-pentanol in water fromT=298 K toT=413 K atp=0.1 MPa andp=19 MPa
1996
Abstract Densities of 1-pentanol aqueous solutions were measured by using a vibrating tube densimeter especially designed and equipped to perform accurate measurements from ambient conditions up toT=423 K andp=80 MPa. The densimeter was tested by measuring densities of NaCl (aq). A comparison with the most reliable literature data showed very good agreement with differences lower than (0.03 and 0.1) kg·m−3for molalities below and above 0.5 mol·kg−1, respectively. From the density measurements, the apparent molar volumes of 1-pentanol in water,Vφwere determined as a function of molalitymat temperatures fromT=298 K toT=413 K atp=0.1 MPa andp=19 MPa. At a given temperature and pressure, and pa…
Effect of ion exchange capacity and water uptake on hydroxide transport in PSU-TMA membranes: A DFT and molecular dynamics study
2020
Abstract Anion Exchange Membranes (AEMs) are nowadays used in a very wide range of different applications, from electrodialytic systems for water treatment, to Fuel Cells for energy generation. In many of these cases, the AEM is in contact with water molecules, either in aqueous or gas phase, which can strongly interact with the AEM polymer, thus affecting membrane properties. The role of water in fully swollen AEM and its effect on the diffusion of hydroxide is the focus of this work. Density Functional Theory (DFT) based calculations were merged with Molecular Dynamics (MD) simulations coming to a more accurate description of the ionic exchange capacity effect on the hydroxide ion diffusi…
Quantitative Analysis of the Interactions of Metal Complexes and Amphiphilic Systems: Calorimetric, Spectroscopic and Theoretical Aspects.
2022
Metals and metal-based compounds have many implications in biological systems. They are involved in cellular functions, employed in the formation of metal-based drugs and present as pollutants in aqueous systems, with toxic effects for living organisms. Amphiphilic molecules also play important roles in the above bio-related fields as models of membranes, nanocarriers for drug delivery and bioremediating agents. Despite the interest in complex systems involving both metal species and surfactant aggregates, there is still insufficient knowledge regarding the quantitative aspects at the basis of their binding interactions, which are crucial for extensive comprehension of their behavior in sol…
A Molecular Dynamics Study of the Structure of an Aqueous KC1 Solution
1986
A molecular dynamics simulation of a 2.2 molal aqueous KCl solution has been performed using the ST2 water model. The simulation extended over 5ps at an average temperature of 288 K. The basic box has a side length of 18.74 A and contained 200 water molecules, 8 cations and 8 anions. The structure of the solution is discussed by radial distribution functions, the orientation of the water molecules, and their geometrical arrangement in the first hydration shells. The first shells of K+ and Cl- extend up to 3.52 and 3.84 A, respectively, with the corresponding hydration numbers 7.8 and 7.6. The results are compared with recent neutron and X-ray diffraction data and with findings of previous M…
Spin Crossover in a Supramolecular Fe4II [2×2] Grid Triggered by Temperature, Pressure, and Light
2000
A multiplex electronic switch on the molecular level has been realized by using a tetranuclear FeII complex of the [2×2] grid type. The four metal ions can be switched stepwise between their high-spin and low-spin states by temperature, pressure, and light, thus representing a triple level, triple switch system as illustrated in the picture.
Design, synthesis and biological evaluation of novel stilbene-based antitumor agents
2008
A series of novel stilbene derivatives has been synthesized and studied with the main goal to investigate SAR of the amino compound 1a, as well as to improve its water solubility, a potentially negative aspect of the molecule that could be a serious obstacle for a pre-clinical development. We have obtained derivatives with good cytotoxic activity, in particular, the derivatives 5c and 6b could represent two novel leads for further investigation. Compound 8b, a morpholino-carbamate derivative, prodrug of 1a, has a very good solubility in water, and is active in suppressing growth of tumor cells at a concentration of 5000 nM, which is a concentration 100 times higher than the parent stilbene …
Cyclopentadienylmolybdenum(VI) and molybdenum(V) oxo chemistry: New synthetic and structural features
2002
International audience; Convenient syntheses for Cp, Cp*, and related cyclopentadienyl derivatives (4Cp = C5HiPr4; Cp′′′ = C5H2tBu3-1,2,4) of formula [(Ring)2Mo2O5] are described. Compound [Cp2Mo2O5] was produced in good yields by the rapid oxidation of red [CpMoO2]4 with PhIO in CH2Cl2. [Cp*2Mo2O5] was obtained by CH3COOH acidification of aqueous solutions of [Cp*MoO3]−Na+, the latter being generated in a single step from [Cp*MoCl4] and more than 5 equiv. of aqueous NaOH in air. Minor quantities of [Cp*MoO2]2 were also isolated from this reaction, although the formation of this by-product may be reduced by using a two-step basic hydrolysis procedure. Extension of the latter strategy also a…
Viscosity solutions of the Monge-Ampère equation with the right hand side in Lp
2007
We compare various notions of solutions of Monge-Ampère equations with discontinuous functions on the right hand side. Precisely, we show that the weak solutions defined by Trudinger can be obtained by the vanishing viscosity approximation method. Moreover, we investigate existence and uniqueness of Lp-viscosity solutions.
Phase separation of polymer blends in solution: A case study
2016
Abstract The phase behavior and phase separation features of the quaternary system poly- l -lactide (PLLA)/poly-rac-lactide (PLA)/dioxane/water were investigated. Experiments were performed with fixed total polymer concentration of 6 wt%, by varying the PLLA/PLA weight ratio. Blend weight compositions examined were 100/0, 80/20, 50/50, 20/80 and 0/100, at fixed dioxane/water weight ratio (87/13). Cloud point measurements reported that the demixing temperatures of blends are close to PLLA in the same mixed solvent, in line with the calculated spinodals. As regards to foam preparation, above the PLA cloud point, morphology is similar to pure PLLA foams; conversely, below PLA cloud point, the …
Preparation of polymeric foams with a pore size gradient via Thermally Induced Phase Separation (TIPS)
2015
Abstract Foams with a pore size gradient are promising materials for tissue engineering applications where a complex architecture involving morphological variations in space must be mimicked, e.g. in bone tissue repair. In this paper, a technique to obtain a porous scaffold with a pore size gradient is presented. The preparation procedure is based on Thermally Induced Phase Separation (TIPS), by imposing a different thermal history on the two sides of a polymeric solution. In this way, a gradient in thermal history is produced, which will generate a pore size monotonously varying along scaffold thickness. By controlling some parameters easy to manipulate, such as demixing temperature and/or…