A Molecular Tetrahedral Cobalt–Seleno-Based Complex as an Efficient Electrocatalyst for Water Splitting

The cobalt–seleno-based coordination complex, [Co{(SePⁱPr₂)₂N}₂], is reported with respect to its catalytic activity in oxygen evolution and hydrogen evolution reactions (OER and HER, respectively) in alkaline solutions. An overpotential of 320 and 630 mV was required to achieve 10 mA cm⁻² for OER and HER, respectively. The overpotential for OER of this CoSe₄-containing complex is one of the lowest that has been observed until now for molecular cobalt(II) systems, under the reported conditions. In addition, this cobalt–seleno-based complex exhibits a high mass activity (14.15 A g⁻¹) and a much higher turn-over frequency (TOF) value (0.032 s⁻¹) at an overpotential of 300 mV. These observations confirm analogous ones already reported in the literature pertaining to the potential of molecular cobalt–seleno systems as efficient OER electrocatalysts.     

The Bellman function of the dyadic maximal operator related to Kolmogorov’s inequality

We precisely evaluate the Bellman function of two variables of the dyadic maximal operator related to Kolmogorov’s inequality, thus giving an alternative proof of the results in [3]. Additionally, we characterize the sequences of functions that are extremal for this Bellman function. More precisely, we prove that they behave approximately like eigenfunctions of the dyadic maximal operator, for a specific eigenvalue.     

Some Weak Forms of the Axiom of Choice Restricted to the Real Line

It is shown that AC(ℝ), the axiom of choice for families of non‐empty subsets of the real line ℝ, does not imply the statement PW(ℝ), the powerset of ℝ can be well ordered. It is also shown that (1) the statement “the set of all denumerable subsets of ℝ has size 2 ${}^{\text{ℵ}{}_{\text{0}}}$ ” is strictly weaker than AC(ℝ) and (2) each of the statements (i) “if every member of an infinite set of cardinality 2 ${}^{\text{ℵ}{}_{\text{0}}}$ has power 2 ${}^{\text{ℵ}{}_{\text{0}}}$ , then the union has power 2 ${}^{\text{ℵ}{}_{\text{0}}}$ ” and (ii) “ℵ(2 ${}^{\text{ℵ}{}_{\text{0}}}$ ) ≠ ℵ_ω” (ℵ(2 ${}^{\text{ℵ}{}_{\text{0}}}$ ) is Hartogs' aleph, the least ℵ not ≤ 2 ${}^{\text{ℵ}{}_{\text{0}}}$ ), is strictly weaker than the full axiom of choice AC.     

Synthesis and mesomorphic behavior of a new series of side-chain liquid crystalline polymethacrylates bearing 2,6-naphthylene-based mesogen

A new homologous series of liquid crystalline (LC) polymethacrylates, the poly[ω-(2-phenoxycarbonyl-naphthalene-6-yloxy)alkyl methacrylate]s, in which the length of the alkyl spacer is varied between 3 and 12 methylene units, have been synthesized by free-radical polymerization. The prepared polymers were studied by IR and ¹H-NMR spectroscopy, viscosity measurements, differential scanning calorimetry (DSC), and polarized microscopy. Polymers with 3 or 4 methylene units spacer were glassy in nature, whereas those with 5–12 methylene units spacer exhibited smectic behavior. The glass transition temperatures decrease on increasing spacer length. The isotropization temperatures and the corresponding transition entropies showed an odd–even effect, with the odd members exhibiting the higher values. This effect attenuates on increasing spacer length. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2391–2399, 1999     

Assessing a set of additive utility functions for multicriteria decision-making,the UTA method

The purpose of the method presented in this paper is to assess additive utility functions which aggregate multiple criteria in a composite criterion, using the information given by a subjective ranking on a set of stimuli or actions (weak-order comparison judgments) and the multicriteria evaluations of these actions. It is an ordinal regression method using linear programming to estimate the parameters of the utility function.Stability and sensitivity analysis leads to the assessment of a set of utility functions by means of post-optimality analysis techniques in linear programming.Finally, a simple illustrative example is presented and some extensions of the method are proposed.     

Potentiometric titration of sulphate, sulphite and dithionate mixtures, with use of a lead ion-selective electrode

Simple methods are described for the analysis of sulphate, sulphite and dithionate mixtures by potentiometric titration with lead perchlorate (and use of a lead ion-selective electrode). The error and precision are both about 2–5% for the sulphate concentration range 3 × 10⁻³ −6 × 10⁻⁴M. The sulphur content in fuels derived from refuse was determined by potentiometric titration after bomb-combustion and the results compared favourably with those from the standard BaSO₄ gravimetric method.     

Assembly of a photoreactive coordination polymer containing rectangular grids

We describe the synthesis, crystal structure and solid state reactivity of cadmium fumarate dihydrate, which is made up of planar H-bonded metal-organic layers and undergoes, upon irradiation, a topochemical [2 + 2] cycloaddition reaction.     

In vitro response of hFOB cells to pamidronate modified sodium silicate coated cellulose scaffolds

The aim of the present study was to evaluate the suitability of cellulose-based scaffolds coated with pure sodium silicate gel and sodium silicate gels accumulated with different concentrations of the bisphosphonate pamidronate as scaffolds for attachment, proliferation and differentiation of human fetal osteoblasts (hFOB 1.19). Human osteoblasts were cultured in vitro for a period up to 14 days on different cellulose scaffolds. Unmodified and sodium silicate coated cellulose scaffolds were used as control. Two surface-coated modifications of cellulose were applied. The scaffolds were coated in a modified two-step dip coating process with pure sodium silicate gel and pamidronate enriched sodium silicate gel, respectively. In order to investigate the influence of the pamidronate, concentrations of 0.667 mg Na-pamidronate/ml sodium silicate solution, 0.333 mg Na-pamidronate/ml sodium silicate solution and 3.33 x 10(-3) mg Na-pamidronate/ml sodium silicate solution were used for the coating process. Cell proliferation, vitality and attachment were examined by means of cell counting, WST-1 test, fluorescence and scanning electron microscopy. The relative grade of differentiation of hFOB cells was examined by using quantitative real-time polymerase chain reaction (qRT-PCR) analysis for the gene expression of alkaline phosphatase and osteocalcin. Proliferation and differentiation of human osteoblasts was enhanced by the sodium silicate coatings accumulated with pamidronate compared to pure sodium silicate coatings. There was a reciprocal correlation of vitality with the concentration of pamidronate. The highest vitality was found on surfaces with the lowest pamidronate accumulation. Alkaline phosphatase, an early differentiation marker, was overexpressed after 7 days in cells on all pamidronate-containing surfaces (up to 350% compared to untreated cellulose). Osteocalcin, a late differentiation marker, was overexpressed after 14 days in cells on all coated surfaces (up to 300,000% compared to untreated cellulose). The results indicate that due to the modified coating procedure a homogeneous coating and thus, an enhancement of cell attachment and subsequent cellular functions can be achieved. Low concentrations of pamidronate seem to have a relevant effect on cell proliferation and vitality and, therefore, can be recommended for the improvement of the properties of a biomaterial.