Thermodynamic and transport properties for binary and ternary mixtures of 2-methyltetrahydrofuran?+?chlorobenzene?+?cyclopentanone at T?=?298.15?K

Abstract  

Experimental densities ρ, viscosities η, and refractive indices n _D of the ternary mixtures consisting of 2-methyltetrahydrofuran + chlorobenzene + cyclopentanone and constituted binary mixtures were measured at T = 298.15 K for the liquid region and at ambient pressure for the whole composition range. Excess molar volumes V_\textm^\textEV_{\text{m}}^{\text{E}}, deviations in the viscosity Δη, and deviations in the refractive index Δn _D from the mole fraction average for the mixtures were derived from the experimental data. The excess partial molar volumes V_\textm,i^\textEV_{{\text{m}},i}^{\text{E}} were also calculated. The binary and ternary data of V_\textm^\textEV_{\text{m}}^{\text{E}}, Δη, and Δn _D were correlated as a function of the mole fraction by using the Redlich–Kister and the Cibulka equations, respectively. McAllister’s three-body interaction model is used for correlating the kinematic viscosity of binary mixtures with the mole fraction.     

A Simple and Eco-Compatible One-Pot Synthesis of New Symmetrical Dithiocarbamate Podands and Their Dynamic NMR Studies

Abstract

A simple and eco-compatible synthesis of podands as 4_a-i is performed using amines (3_a-c ), CS₂, and dichlordiamides (DCDs) (2_{a, c} ) in the absence of a catalyst in water. Three reacting DCDs (2_a-c ) were obtained in the reaction of aromatic diamines (1_{a, c} ) with chloroacetyl chloride. Dynamic NMR spectroscopic data of three series of podands (4_a-c , 4_d-f , and 4_g-i ) are discussed and their free energies of activations are calculated (ΔG ^≠ _c s) at coalescence temperatures. The ΔG ^≠ _c of these podands were attributed to conformational isomerization in the range of 14.7–17 kcal/mol due to rotation and resonance effects about the thioamide C?N bond.

[Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional figures.]     

Comparative essential oil composition of aerial parts of Tanacetum dumosum Boiss. from Southern Zagros,Iran.

The essential oils of leaves and flowers of Tanacetum dumosum Boiss., an endemic medicinal shrub, were extracted by using hydrodistillation method and analysed using GC and GC–MS. A total of 43 and 44 compounds were identified in the essential oils from the leaves and flowers of T. dumosum, respectively. The major chemical constituents of leaves oil were borneol (27.9%), bornyl acetate (18.4%), 1,8-cineol (17.5%), α-terpineol (5.3%), cis-chrysanthenyl acetate (3.3%), camphene (2.7%) and terpinene-4-ol (1.9%), while the main components of the flower oil were isobornyl-2-methyl butanoate (41.1%), trans-linalyl oxide acetate (11.9%), 1,8-cineole (7.7%), thymol (4.2%), linalool (3.9%), camphor (2.9%), isobornyl propanoate (2.9%), α-terpineol (2.1%) and caryophyllene oxide (2.0%). Major qualitative and quantitative variations for some main chemical compounds among different aerial parts of T. dumosum were identified. High contents of borneol, bornyl acetate, 1,8-cineol and linalool in the leaves and flowers of T. dumosum show its potential for use in the food and perfumery industry.     

Finite-element simulation of ultrasound brain surgery: effects of frequency, focal pressure, and scanning path in bone-heating reduction

In this paper, the finite-element method (FEM) simulation of ultrasound brain surgery is presented. The overheating problem of the post-target bone, which is one of the limiting factors for a successful ultrasound brain surgery, is considered. In order to decrease bone heating, precise choices of frequency, focal pressure, and scanning path are needed. The effect of variations in the mentioned scanning parameters is studied by means of the FEM. The resulting pressure and temperature distributions of a transdural ultrasound brain surgery are simulated by employing the FEM for solving the Helmholtz and bioheat equations in the context of a two-dimensional MRI-based brain model. Our results show that for a suitable value of the frequency, an increase in focal pressure leads to a decrease in the required duration of the treatment and is associated with less heating of the surrounding normal tissue. In addition, it is shown that at a threshold focal pressure, the target temperature reaches toxic levels whereas the temperature rise in the bone is minimal. Wave reflections from sinus cavities, which result in constructive interference with the incoming waves, are one of the reasons for overheating of the bone and can be avoided by choosing a suitable scanning path.      

Determination of desipramine in biological samples using liquid–liquid–liquid microextraction combined with in‐syringe derivatization,gas chromatography,and nitrogen/phosphorus detection

A method was established for the determination of desipramine in biological samples using liquid–liquid–liquid microextraction followed by in‐syringe derivatization and gas chromatography–nitrogen phosphorus detection. The extraction method was based on the use of two immiscible organic solvents. n‐Dodecane was impregnated in the pores of the hollow fiber and methanol was placed inside the lumen of the fiber as the acceptor phase. Acetic anhydride was used as the reagent for the derivatization of the analyte inside the syringe barrel. Parameters that affect the extraction efficiency (composition of donor and acceptor phase, ionic strength, sample temperature, and extraction time) as well as derivatization efficiency (amount of acetic anhydride and reaction time and temperature) were investigated. The limit of detection was 0.02 μg/L with intra and interday RSDs of 2.6 and 7.7%, respectively. The linearity of the method was in the range of 0.2–20 μg/L (r² = 0.9986). The method was successfully applied to determine desipramine in human plasma and urine.     

Anomalous codeposition of cobalt and ruthenium from chloride–sulfate baths

Codeposition of Ru and Co was studied at room temperature and at 50 °C with various Ru³⁺ and Co²⁺ concentrations in the electrolyte. The codeposition of Co and Ru proved to be anomalous since no pure Ru could be obtained in the presence of Co²⁺ in the electrolyte, but a significant Co incorporation into the deposit was detected at potentials where the deposition of pure Co was not possible. The composition of the deposits varied monotonously with the change of the concentration ratio of Co²⁺ and Ru³⁺. The deposition of Ru was much hindered, and the current efficiency was a few percent only when the molar fraction of Co in the deposit was low. Continuous deposits could be obtained only when the molar fraction of Co in the deposit was at least 40 at.%. The deposit morphology was related to the molar fraction of Co in the deposit. The X-ray diffractograms are in conformity with a hexagonal close-packed alloy and indicate the formation of nanocrystalline deposits. Two-pulse plating did not lead to a multilayer but to a Co-rich alloy. Magnetoresistance of the samples decreased with increasing Ru content.     

Microwave-assisted efficient synthesis of azlactone derivatives using TsCl/DMF under solvent-free conditions

A simple and efficient procedure for the synthesis of azlactones employing condensation reaction of aromatic aldehydes with hippuric acid has been developed by using the tosyl chloride (TsCl) and dimethylformamide (DMF) system as condensing agent in the absence of solvents under microwave irradiation. The present protocol is operationally simple and offers several advantages such as high yields, short reaction time, and simple workup.     

Synthesis and characterization of a novel solvent-free dextran-HEMA-PNIPAM thermosensitive nanogel

In recent years, the polymeric nanogels, as a group of nanostructured materials, have attracted the attention of researchers of various fields such as polymers, materials science, pharmacy, and drug delivery. Gels are mostly known for their water-swellable features and are candidates for a variety of applications. In this work, a facile solvent free synthesis procedure for production of dextran-hydroxyethyl methacrylate (Dex-HEMA) and poly N-isopropyl acryl amide (PNIPAM) copolymeric nanogels is narrated. The polymerization process was conducted by the UV irradiation and the gel size was controlled by the liposomal structures. The H-NMR and FTIR analysis were all proved a successful polymerization procedure. By implication of the dynamic light scattering (DLS), the mean diameter of particles was determined to be in the range of ca. 350 nm. The molecular weight determination by the GPC results in the Mw ranging from 16100 to 20900 gr mol^?1 with a polydispersity index of ca. 1.5. The turbidity assay indicated the thermosensitive nature of the gels and a LCST of ca. 32.5 was characterized. In this work, the equilibrium swelling measurements and the water content studies at two temperatures of 25 and 37°C were also performed.     

Numerical Study of Spin-Dependent Transport Through a Magnetic Quantum Wire with Lattice Vacancy

The impact of lattice vacancy on the spin dependent transport properties of a magnetic-quantum wire (MQW) has been investigated. A simple tight binding Hamiltonian to describe the model is used, where the quantum wire is attached to two semi-infinite one-dimensional non-magnetic electrodes. Based on the Landauer–Buttiker formalism all the calculations are performed numerically which describe two-terminal conductance. The results suggest that in presence of vacancy the transmission reduces and vacancy creates quasilocalized states around zero energy (E _f = 0). In order to investigate spin-filtering effect of (MQW), the degree of polarization in the presence and absences of vacancy has been studied. Also it is found that the effect of vacancy decreases when the size of MQW increases. The results show that a magnetic quantum wire can be used as a spin filter. The application of the predicted results may be useful in designing molecular spin-polarized transistors in the future.     

Modified jerk system with self-exciting and hidden flows and the effect of time delays on existence of multi-stability

In this paper, we report a new chaotic jerk system which shows self-excited and hidden oscillations depending on its parameters. Dynamic analysis shows that the proposed system exhibits multi-stability and coexisting attractors. To study the effect of time delays on the multi-stability feature of the system, we introduce multiple time delays in the third state variable. Investigation of dynamical properties of the time-delayed system shows the disappearance of multi-stability. Such a feature has not been reported earlier in the literatures.