Rapid annulation of tropolone units via a pyrylium ylide 1,3-dipolar cycloaddition reaction

The tropolone subunit of the naturally occurring alkaloid rubrolone aglycon is synthesized via a short reaction sequence starting with a 1,3-dipolar cycloaddition of a pyrylium ylide and indenone, followed by enone oxidation, oxygen-bridge elimination and finally hydroxy group oxidation.     

Liquid-phase epitaxy of multicomponent layer-based porous coordination polymer thin films of [M(L)(P)0.5] type: importance of deposition sequence on the oriented growth

The progressive liquid-phase layer-by-layer (LbL) growth of anisotropic multicomponent layer-based porous coordination polymers (PCPs) of the general formula [M(L)(P)(0.5)] (M: Cu(2+), Zn(2+); L: dicarboxylate linker; P: dinitrogen pillar ligand) was investigated by using either pyridyl- or carboxyl-terminated self-assembled monolayers (SAMs) on gold substrates as templates. It was found that the deposition of smooth, highly crystalline, and oriented multilayer films of these PCPs depends on the conditions at the early growth cycles. In the case of a two-step process with an equimolar mixture of L and P, growth along the [001] direction is strongly preferred. However, employing a three-step scheme with full separation of all components allows deposition along the [100] direction on carboxyl-terminated SAMs. Interestingly, the growth of additional layers on top of previously grown oriented seeding layers proved to be insensitive to the particular growth scheme and full retention of the initial orientation, either along the [001] or [100] direction, was observed. This homo- and heteroepitaxial LbL growth allows full control over the orientation and the layer sequence, including introduction of functionalized linkers and pillars.     

Spin-glass behavior in LaFe(x)Co(2-x)P2 solid solutions: interplay between magnetic properties and crystal and electronic structures

To explore the evolution of magnetic properties from ferromagnetic LaCo(2)P(2) to paramagnetic LaFe(2)P(2) (both of ThCr(2)Si(2) structure type) a series of mixed composition LaFe(x)Co(2-x)P(2) (x ≤ 0.5) has been comprehensively investigated by means of single-crystal and powder X-ray and neutron diffraction, magnetization and heat capacity measurements, M?ssbauer spectroscopy, and electronic band structure calculations. The Curie temperature decreases from 132 K in LaCo(2)P(2) to 91 K in LaFe(0.05)Co(1.95)P(2). The ferromagnetic ordering is suppressed at higher Fe content. LaFe(0.1)Co(1.9)P(2) and LaFe(0.2)Co(1.8)P(2) demonstrate spin-glass-like behavior, which was also confirmed by the absence of characteristic features of long-range magnetic ordering, namely, a λ-type anomaly in the heat capacity, a hyperfine splitting in the M?ssbauer spectrum, and magnetic reflections in the neutron diffraction pattern. Finally, both LaFe(0.3)Co(1.7)P(2) and LaFe(0.5)Co(1.5)P(2) exhibit paramagnetic behavior down to 1.8 K. The unit cell parameters of the mixed compounds do not follow the Vegard behavior as the increase in the Fe content results in the decrease of average M-M distances (M = Fe, Co). Quantum-chemical calculations and crystal orbital Hamiltonian population analysis reveal that upon aliovalent (nonisoelectronic) substitution of Fe for Co the antibonding character of M-M interactions is reduced while the Fermi level is shifted below the DOS peak in the 3d metal subband. As the result, at higher Fe content the Stoner criterion is not satisfied and no magnetic ordering is observed.     

Lipophilic toxin profile in Mytilus galloprovincialis during episodes of diarrhetic shellfish poisoning (DSP) in the N.E. Adriatic Sea in 2006

Dinophysis spp. blooms and related shellfish toxicity events of diarrhetic shellfish poisoning (DSP) have been the most reported toxicity event through the Croatian National monitoring program. With the aim to characterize the DSP toxin profile in shellfish farmed in Croatia, for the first time a complete analysis of the toxin profile of Croatian mussels has been carried out using the LC-MS/MS technique. The obtained results showed okadaic acid (OA) as the main toxin contaminating Croatian mussels at that time. The maximum concentration of OA in shellfish tissue was recorded 12 days after the Dinophysis fortii bloom, thus suggesting that rapid growth of the toxin level in the shellfish occurred in the first week after the bloom while it was slower in the second week. Furthermore, the presence of only OA at concentrations which could endanger human health suggests D. fortii as the main organism responsible for the toxic event that occurred in Lim Bay. The presence of gymnodimine and spirolides in Croatian mussel has been detected for the first time, while the presence of yessotoxin and pectenotoxin-2 is confirmed.     

Approximation ofk-Monotone Functions

It is shown that an algebraic polynomial of degree k−1 which interpolates ak-monotone functionfatkpoints, sufficiently approximates it, even if the points of interpolation are close to each other. It is well known that this result is not true in general for non-k-monotone functions. As an application, we prove a (positive) result on simultaneous approximation of ak-monotone function and its derivatives inL_p, 0<p<1, metric, and also show that the rate of the best algebraic approximation ofk-monotone functions (with bounded (k−2)nd derivatives inL_p, 1<p<∞, iso(n^−k/p).     

Solubility in the Fullerene C6 0-Fullerene C7 0-o-C6H1 4(CH3)2 System

The solubility diagram of the ternary fullerene-containing system C₆₀-C₇₀-o-xylene at 25 and -20°C was studied.     

Carbon nanostructures in the industrial production of alkali metals by electrolysis

The carboniferous component of slimes in the electrolytic production of alkali metals (in our case, lithium) is studied for the first time with the aim to find nanostructures in it. The content of nanostructures in this component, which accounts for 10% of the slimes and can be separated by mild chemical treatment, is shown to be 2–4%. These structures are multiwall nanotubes or bundles of multiwall nanotubes, most of which are open. No twisted or single-wall nanotubes have been detected.