On the performance of the intermediate Hamiltonian Fock-space coupled-cluster method on linear triatomic molecules: The electronic spectra of NpO2+, NpO2(2+), and PuO2(2+)

In this paper we explore the use of the novel relativistic intermediate Hamiltonian Fock-space coupled-cluster method in the calculation of the electronic spectrum for small actinyl ions (NpO2+, NpO2(2+), and PuO2(2+)). It is established that the method, in combination with uncontracted double-zeta quality basis sets, yields excitation energies in good agreement with experimental values, and better than those obtained previously with other theoretical methods. We propose the reassignment of some of the peaks that were observed experimentally, and confirm other assignments.     

A QM/MM study on the aqueous solvation of the tetrahydroxouranylate [UO2(OH)4]2- complex ion

We report a QM augmented QM/MM study on the coordination of the tetrahydroxouranylate ion in aqueous solution. QM/MM geometry optimizations followed by full QM single-point calculations on the optimized structures show that a hexa-coordinated structure is more stable than the hepta-coordinated structure by 43 kJ/mol. Charge transfer of the tetrahydroxouranylate to the solvating water molecules is relatively modest, and can be modeled by including a solvation layer consisting of 12 explicit water molecules.     

Loss of positivity in a nonlinear scalar heat equation

Using the theory of fixed point index, we discuss the existence of nontrivial (multiple) solutions of a nonlinear scalar heat equation with nonlocal boundary conditions depending on a positive parameter. Solutions lose positivity as the parameter decreases. For a certain parameter range, not all solutions can be positive but there are positive solutions for certain types of nonlinearity. We also prove a uniqueness result.     

A Cauchy–Pompeiu Representation Formula Using Dirac Operator and its Applications in Some Piecewise Constant Structure Relations

In the present paper we use the piecewise constant structure relations of a Clifford algebra in order to obtain a Cauchy–Pompeiu representation for D ? λ and D + λ operators, with these formulas we construct a distributional solutions for the equations that involves these operators with arbitrary right hand side. We also present an example where we build an integral representation for combinations of these operators.     

A Multi‐purpose Flow System Based on Multi‐commutation

A multi‐purpose flow system designed with solenoid valves and micropumps is proposed. The independent control of each active device was exploited to implement dilutions, calibration with a single solution, standard additions, titrations and strategies to increase sample residence time without changing the manifold hardware. Sample dispersion coefficients between 1 and 7800 were achieved by changing the sample volume and exploiting zone sampling, with coefficient of variation estimated as 6.5% for the highest dilution. Calibration curves obtained from a single standard showed slopes in agreement with those obtained by conventional batch dilutions with variations of lower than 2% between days. The possibility of implementing the standard addition method or the stopped‐flow approach at different points of the manifold was demonstrated for creatinine determination in urine by the Jaffe reaction. Analytical curves for different sample residence times can be obtained for detecting matrix effects or for the analysis of colored samples. Titrations by the continuous variation method or binary search, as well as other possible applications, are discussed.     

Some Integral Representation for Meta-Monogenic Function in Clifford Algebras Depending on Parameters

In recent years, the integral representation problems have been studied in many context and generalities. For example, for the monogenic and meta functions in some Clifford type algebras, see [10, 11]. In this paper we construct a Cauchy-Pompeiu type formula for meta-monogenic operator of order ${n, (D-\lambda)^n, \lambda \in \mathbb{R}}$ , and its conjugate ${(\overline{D} - \lambda)^n}$ in a Clifford algebra depending on parameters ${\mathcal{A}_n(2, \alpha_j, \gamma_{ij})}$ . Using these explicit representation formula of Cauchy-Pompeiu type we will show some applications.     

Pro-oxidant activity of aluminum: stabilization of the aluminum superoxide radical ion

The pro-oxidant activity of aluminum, a nonredox metal, through superoxide formation is studied by theoretical methods, determining the ESR g-tensor values of O2(?–) with a variety of metals and the reaction energies for Al3+ superoxide affinity in solution. First, the intrinsic ability of aluminum to induce a splitting of the πg levels is compared to that of other significant biological metals, such as Na+, K+, Mg2+, and Ca2+. Additional properties such as bond lengths, ionization potentials, and electron affinities are also determined, and the coherency with the trends observed from ESR g-tensor values is analyzed. As it corresponds to the high charge and its small size, there is a strong interaction between Al3+ and the superoxide. We predict that this strong inherent interaction remains when aluminum is microsolvated. Finally, we analyze the possibility of Al3+ superoxide formation in solution, leading to the conclusion that substitution of the first coordination shell water molecules is plausible, but not of hydroxides. This points to the possibility of Al3+ superoxide formation in solution, which would be pH-dependent. Taking into account the earlier established linear relationship between metal–superoxide interactions and promoting effects in electron-transfer reactions, our work reinforces the idea that the presence of aluminum in biological systems could lead to an important pro-oxidant activity through a superoxide formation mechanism.