Prediction of Solubility Parameters Based on the Explicit Expression of Statistical Thermodynamics

A robust and efficient procedure is presented for calculating the solubility parameter. An analytical equation for internal pressure is proposed. Through a simple relation reported by Verdier and Andersen (fluid phase equilibrium 231: 125–137, 2005), one can easily find the solubility parameter via our analytical equation for the internal pressure. Also, the radial distribution function (RDF) of a Lennard–Jones LJ (12, 6) fluid, proposed by Xu and Hu (fluid phase equilibrium 30: 221–228, 1986), has been employed to calculate the internal pressure of normal alkanes from methane to decane. Their solubility parameters were evaluated according to the calculated values of the internal pressure. A comparison between the experimental and the estimated values demonstrated a very good agreement between them.     

Determination of vanadium in serum by pre-irradiation and post-irradiation chemistry and neutron activation analysis

Vanadium in serum was investigated by pre-irradiation chemistry neutron activation analysis employing anion exchange chromatography and post-irradiation neutron activation employing solvent extraction techniques. From a comparison of these techniques it is concluded that vanadium is present in human serum in the sub-ppb range.     

Synthesis,crystal structures and spectra of Hg(II)-1,2-bis(diphenylphosphino)ethane monoxide complexes: Monomer and polymer formation

The reaction of mercury(II) halides with 1,2-bis(diphenylphosphino)ethane monoxide (dppeO) in 1:1 molar ratio yielded P,O-coordinated polymers having the empirical formula [HgX₂(dppeO)]_n [X = Cl (1), Br (2), I (3)]. In contrast, the reaction between the same reactants in a 1:2 molar ratio yielded the P, P-coordinated monomeric complexes, HgX₂(dppeO)₂[X = Cl (4), Br (5), I (6)]. The structures of 2, 3, 4 and 5 have been characterized crystallographically. The results indicate that the geometry around the mercury atom in each of these molecules is tetrahedral with considerable distortion. The ³¹P NMR spectra of the 1:1 complexes indicate the dissociation of the Hg–O bond in solution.     

A mild conversion of arylboronic acids and their pinacolyl boronate esters into phenols using hydroxylamine

Hydroxylamine was found to be a mild reagent for conversion of arylboronic acids and their pinacolyl boronate esters into phenols. This procedure works on most arylboronic acids at room temperature, yielding phenols in moderate to good yields, and efficiently on arylboronates also yielding phenols in good yields.     

An unexpected, novel, three-component reaction between isoquinoline, an isocyanide and strong CH-acids in water

An unexpected three-component condensation reaction between an isocyanide, isoquinoline and a strong CH-acid efficiently provides 1,2-dihydroisoquinoline derivatives in a one-pot reaction in water at 70 °C without using any catalyst.     

Environmentally benign and highly regioselective ring opening of epoxides accelerated by ultrasound irradiation

Regioselective ring opening of aliphatic and aromatic epoxides with nitrogen heterocycles such as indoles and imidazoles was accelerated using an ultrasonic technique as a green approach. An optimized procedure with the catalyst of choice, MCM-41, represents a real alternative to the conventional reaction protocols owing to the catalyst recyclability, simplicity, green conditions and time-saving aspects.     

Volatile constituents of flowers and leaves of Anthemis hyalina

The chemical composition of the essential oils of the flowers and leaves of Anthemis hyalina were analyzed by GC and GC-MS for the first time. The oils were found to contain seventy-two components. cis-Chrysanthenyl acetate (14.9% and 17.8%), camphor (11.6% and 1.7%), terpinen-4-ol (8.3% and 1.2%), germacrene-D (5.1% and 2.1%), β-caryophyllene (4.1% and 5.4%), myrcene (3.6% and 16.9%), bicyclogermacrene (3.5% and 0.9%), α-pinene (2.3% and 4.1%), cis-β-ocimene (2.1% and 4.3%) and isospathulenol (0.4% and 4.3%) were found to be the major constituents of the oils of flowers and leaves respectively. Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 428–429, September–October, 2006.     

Matrix Heterogeneity Effects on Gas Transport and Adsorption in Coalbed and Shale Gas Reservoirs

In coalbeds and shales, gas transport and storage are important for accurate prediction of production rates and for the consideration of subsurface greenhouse gas sequestration. They involve coupled fluid phenomena in porous medium including viscous flow, diffusive transport, and adsorption. Standard approach to describe gas–matrix interactions is deterministic and neglects the effects of local spatial heterogeneities in porosity and material content of the matrix. In this study, adopting weak-noise and mean-field approximations and using a statistical approach in spectral domain, matrix heterogeneity effects are investigated in the presence of non-equilibrium adsorption with random partition coefficient. It is found that the local heterogeneities can generate non-trivial transport and kinetic effects which retard gas release from the matrix and influence the ultimate gas recovery adversely. Macro-transport shows 1/[1 + N _Pe /(1 + N _Pe )] dependence on the Péclet number, and persists at the diffusive ultra-low permeability limit. Macro-kinetics is directly related to Thiele modulus by the following expression: N _Th /(1 + 2N _Pe ). It leads to trapping of gas in the adsorbed phase during its release from the matrix, and to an adsorption threshold during the gas uptake by the matrix. Both effects are proportional to the initially available adsorbed gas amount and becomes more pronounced with the increasing variance of the porosity field. Consequently, a new upscaled deterministic gas mass balance is proposed for practical purposes. Numerical results are presented showing free and adsorbed gas distributions and fractional gas sorption curves for unipore coal matrix exhibiting Gaussian porosity distribution. This study is a unique approach for our further understanding of the coalbeds and gas shales, and it is important for the development of sound numerical gas production and sequestration models.     

A New Approach for Optimization of Distributed Quantum Circuits

International Journal of Theoretical Physics - In the present work, a novel approach was proposed to optimize the teleportation cost in Distributed Quantum Circuits (DQCs) by applying a new...