Carbamate Formation and Amine Protonation Constants in 2-Amino-1-Butanol–CO<Subscript>2</Subscript>–H<Subscript>2</Subscript>O System and Their Temperature Dependences

The apparent protonation constant of an amino butanol (AB) and its carbamate formation constant in the CO₂–H₂O–AB system were determined at T = 298.15–328.15 K, and at various ionic strengths up to 0.2 mol·L^?1 by potentiometric titration. The Debye–Hückel equation was used to extrapolate the protonation constants to zero ionic strength. The variation of the thermodynamic equilibrium constant for carbamate formation with temperature was modeled according to the relationship of log₁₀ K₁ = 280.91/T ? 0.1105, while the temperature dependency of the amine protonation constant was correlated by log₁₀ K₂ = 1926.53/T + 2.9482. Van’t Hoff type plots of the pK values showed linear relationships indicating that the standard enthalpy changes of reaction are constant over this range of temperatures. Hence, our current findings are crucial for designing efficient unit operations involving separation of CO₂ from natural or flue gases.     

Rationalization of the behavior of M2(CH3CS2)4I (M = Ni,Pt) chains at room temperature from periodic density functional theory and ab initio cluster calculations

The electrical conductivities and plausible charge‐ordering states in the room temperature (r.t.) phase for MMX chains [Ni₂(dta)₄I]_∞ and [Pt₂(dta)₄I]_∞ (dta = CH₃CS) have been analyzed with periodic density functional theory (DFT) and correlated ab initio calculations combined with the effective Hamiltonian theory. Periodic DFT calculations show a more delocalized nature of the ground state in [Pt₂(dta)₄I]_∞ compared to [Ni₂(dta)₄I]_∞, which features a rather large energy gap between the occupied and empty bands, and charge polarized dimer units. A larger electrical conductivity for the Pt chain can be expected, especially because the Fermi level lies within a band with contributions from Pt and I orbitals. Electronic structure parameters extracted from ab initio cluster calculations show that the large difference between the observed conductivities at 300 K for Ni and Pt compounds, of 3 orders of magnitude, cannot be explained from the parameters extracted from an embedded M₂(dta)₄I₂ dimer fragment alone. When tetramer fragments are considered, we observe that the interdimer transfer integral (t) between neighboring M₂ units connected by an iodine atom at correlated level is comparable in both chains. On the other hand, the energy to transfer an electron from a dimer to the neighboring one (Coulomb repulsion U) is three times larger in the Ni compound with respect to the Pt chain, in line with the poor conductivity of the former. The electronic structure of the M₄(dta)₈I₃ fragment points to an alternate charge‐polarization state for Ni and an average valence state for Pt when the r.t. X‐ray structure is considered. © 2012 Wiley Periodicals, Inc.     

$${\overline{1}}$$ 1 ¯ -Evaluating linear functionals on function spaces

Positivity - Let C(X) denotes the Riesz algebra of all real valued continuous functions on a Tychonoff space X, and let L be a vector subspace of C(X). A linear functional $$H:L\rightarrow {\mathbb...     

Nickel Ion-Selective PVC Membrane Electrode Based on a New t-Octyl-Calix[6]arene Derivative

This study presents a PVC membrane based on 5,11,17,23,29,35-Hexakis-t-octyl-37,38,39,40,41,42-hexakis(N-phenylthiocarbamoylmethoxy)calix[6]arene which is used as an electroactive substance. The electrode reveals a Nernstian response for Ni²⁺ over a wide pH range with a slope of linear portion (5×10^–6–1×10^–2M, R=0.988) of 29.75±0.2mV·decade^–1 at 25°C. The electrodes sensitivity is enhanced upon the introduction of sodium tetraphenylborate into the membrane as a negatively charged lipophilic additive. The selectivity coefficients of various interfering ions were determined using the fixed interference method (FIM). The membrane reveals good selectivity for nickel ions over the other metal ions investigated. The lifetime of this electrode is about one month. This electrode has been applied to the determination of nickel ions in wastewater from the electroplating industry.     

Size and shape controlled of α-Fe2O3 nanoparticles prepared via sol–gel technique and their photocatalytic activity

Journal of Sol-Gel Science and Technology - Haematite (α-Fe2O3) nanoparticles (NPs) of different sizes and morphologies were prepared from two different iron precursors (iron acetate (A) and...     

A generalization of a theorem by Bigard–Keimel and Conrad–Diem

Let G be an archimedean ℓ-group and \mathfrakP(G){\mathfrak{P}(G)} denote the set of all polar preserving bounded group endomorphisms of G. Bigard and Keimel in [Bull. Soc. Math. France 97 (1969), 381–398] and, independently, Conrad and Diem in [Illinois J. Math. 15 (1971), 222–240] proved that \mathfrakP(G){\mathfrak{P}(G)} is an archimedean ℓ-group with respect to the pointwise addition and ordering. This classical result is extended in this paper to certain sets of disjointness preserving bounded homomorphisms on archimedean ℓ-groups.     

Maximal ideals of disjointness preserving operators

Let L and M be vector lattices with M Dedekind complete, and let Lr(L,M) be the vector lattice of all regular operators from L into M. We introduce the notion of maximal order ideals of disjointness preserving operators in Lr(L,M) (briefly, maximal δ-ideals of Lr(L,M)) as a generalization of the classical concept of orthomorphisms and we investigate some aspects of this ‘new’ structure. In this regard, various standard facts on orthomorphisms are extended to maximal δ-ideals. For instance, surprisingly enough, we prove that any maximal δ-ideal of Lr(L,M) is a vector lattice copy of M, when L, in addition, has an order unit. Moreover, we pay a special attention to maximal δ-ideals on continuous function spaces. As an application, we furnish a characterization of lattice bimorphisms on such spaces in terms of weigthed composition operators.     

Reduction of the adjoint representation of sl(2,1): generators of primitive ideals

We present a reduction of the adjoint representation of the Lie superalge-bra,sl(2,1) and a study of the quotient algebra B(^c,k)= u/u(C?c)+u(D?kc), where c,k are two complex numbers. Under some additional conditions, we prove that every irreducible infinite dimensional representation of B(^c,k) is faithful, and that B(^C,K) is a primitive algebra. We give explicitly a set of generators of primitive degenerate ideal of infinite codimension. Essentially we prove that any minimal primitive ideal of u(sl(2,1)) is generated, as a 2-sided ideal, by its intersection with the algebra of gg-iuvariants.