Vapor–liquid equilibria of asymmetrical systems using UNIFAC-NRF group contribution activity coefficient model

The UNIFAC-NRF group contribution activity coefficient model is used for the calculation of vapor–liquid equilibria of binary systems of the heavy alkanes and light gases such as CH₄, C₂H₆, CO₂ and N₂. The linear combination mixing rule, LCVM, of the Huron–Vidal and Michelsen, Chen et al. modification of PSRK and Universal Group Contribution Equation of State of Ahlers and Gmehling are combined with the UNIFAC-NRF group activity coefficient model to correlation of the vapor–liquid equilibrium of both light and heavy hydrocarbons. The results show that the LCVM mixing rule combing with UNIFAC-NRF group contribution model correlate the asymmetric systems better than the LCVM-UNIFAC and the other EOS/G^E models. Also the group contribution model is used for the prediction of the phase envelope of the synthetic fluid with accurate results.     

Axisymmetric wave propagation of thermoelastic transversely isotropic half-space under buried loading using potential functions

By virtue of a new scalar potential function and Hankel integral transforms, the wave propagation analysis of a thermoelastic transversely isotropic half-space is presented under buried loading and heat flux. The governing equations of the problem are the differential equations of motion and the energy equation of the coupled thermoelasticity theory. Using a scalar potential function, these coupled equations have been uncoupled and a six-order partial differential equation governing the potential function is received. The displacements, temperature, and stress components are obtained in terms of this potential function in cylindrical coordinate system. Applying the Hankel integral transform to suppress the radial variable, the governing equation for potential function is reduced to a six-order ordinary differential equation with respect to z. Solving that equation, the potential function and therefore displacements, temperature, and stresses are derived in the Hankel transformed domain for two regions. Using inversion of Hankel transform, these functions can be obtained in the real domain. The integrals of inversion Hankel transform are calculated numerically via Mathematica software. Our numerical results for displacement and temperature are calculated for surface excitations and compared with the results reported in the literature and a very good agreement is achieved.     

Calculation of<Emphasis Type="Italic">Z</Emphasis><Subscript>eff</Subscript> from plasma resistivity in IR-T1 tokamak

The effective ion charge,Z _eff, represents the average charge of ionsZ _i of gasses inside the system, which indicates the level of the impurities in the plasma. Several techniques have been applied to estimateZ _eff, like mass spectroscopy, anomaly factor and Bremsstrahlung radiation.

We estimatedZ _eff in the IR-T1 tokamak through anomaly factor. The IR-T1 tokamak is a small air-core transformer tokamak with circular cross section and with out conducting shell and divertor. Its aspect ratio is

$$\frac{R}{a} = \frac{{45 cm}}{{12.5 cm}}.$$

For a tokamak discharge of 30 kA plasma current and 1.5 V of loop voltage and by anomaly factor we observed thatZ _eff value is about 1.5.     

Dispersion properties of a dusty plasma containing nonspherical rotating dust grains

The dispersion relation for a dusty plasma containing elongated and rotating charged dust grains is obtained by assuming that the dipole moments of the dust particulates are nonzero. The longitudinal waves with frequency close to the angular rotation frequency of the dust grains are found to be unstable. The results should be relevant to enhanced fluctuations in astrophysical environments.     

A first-principle DFT study of solvent effects on metiamide tautomers and imaginary interactions with H<Subscript>2</Subscript>-receptors

Metiamide is a class of medications called H₂-receptor antagonist or H₂ blockers. It decreases the amount of acid made in the stomach. It is commonly used in the treatment for peptic ulcer disease and gastroesophageal reflux disease. In this study, the metiamide tautomer stability, structural data, HOMO and LUMO (energies and shapes), ΔΕ _HOMO–LUMO gaps, UV–visible data and graphs, dipole moments, Mulliken charges, and thermodynamic and kinetic stabilities in aqueous media as a biological solvent and some of the different media (vacuum, H₂O, Et-OH and DMSO) were investigated for the tautomers of metiamide by the density functional theory DFT-B3LYP/6-31G* method. The results presented that the probability of the adaptability and compatibility of which tautomer (T1–T6) are better than the other tautomers for interactions with the pattern and structural map of the H₂-receptor. The diversities of the interaction points and mosaic patterns of the T3 and T4 tautomers in H₂O media with the imaginary H₂-receptor were investigated.     

Novel potentiometric membrane sensor based on 6-(4-nitrophenyl)-2-phenyl-4,4-dipropyl-3,5-diaza-bicyclo[3,1,0] hex-2-ene for detection of strontium (II) ions at trace levels

A new PVC membrane strontium ion-selective electrode has been constructed using 6-(4-nitrophenyl)-2-phenyl-4,4-dipropyl-3,5-diaza-bicyclo[3,1,0] hex-2-ene (NPDBH) as a neutral ionophore. The electrode was prepared with 7% NPDBH (as ionophore), 57% acetophenone (as plasticizer), 30% PVC and 6% oleic acid (as lipophilic additive). The electrode responds to Sr²⁺ ion with a sensitivity of 28.2 ± 0.5 mV/decade over the range 1.0 × 10⁻⁶-1.0 × 10⁻¹ mol L⁻¹ and in a pH range of 3.0-10.0. The limit of detection was 2.4 × 10⁻⁷ mol L⁻¹. It has a response time of <20 s and can be used for at least three months without any divergence in potentials. The proposed electrode shows good discrimination of Sr²⁺ ion from several cations. The effect of organic solvents on electrode response was examined. The results show that this electrode can be used in ethanol media up to 15% (v/v) concentration without interference. The isothermal temperature coefficient of this electrode amounted to 0.00019 V/°C. The electrode was found to work well under laboratory conditions. It was successfully applied to the determination of strontium ions in human urine and bone digests.     

Synthesis of new bis-benzylidene-hydrazides as a sensitive chromogenic sensor for naked-eye detection of CN¯ and AcO¯ ions

Some new bis-benzylidene-hydrazides were synthesized via a condensation reaction of the corresponding azo dyes with adipic acid dihydrazide. All compounds because of the three possible stereoisomers showed four sets of signals in NMR. The anion recognition studies exhibited that the nitro bis-benzylidene-hydrazide derivative acts as a highly sensitive and selective chromogenic sensor for naked-eye detection of CN¯ and AcO¯ ions, with a distinct color change from yellow to blue and yellow to purple, respectively. The limit of detection (LOD) was found for 1d toward CN¯ to be 1.1?μM. The result of the Job's plot indicated stoichiometry of binding between chemosensor and anions is found to be 1:2.