Further Results for kth order Kantorovich Modification of Linking Baskakov Type Operators

In this paper we consider a non-trivial link between Baskakov type operators and their genuine Durrmeyer type modification as well as the kth order Kantorovich variant. Recursion formulas for the moments and the images of monomials are proved in order to derive asymptotic expansions. Furthermore we investigate convexity properties of the linking operators and the limiting behavior for certain function spaces.     

Reaction of O-trimethylsilylated cyanohydrins with α-bromoesters: a new synthesis of tetronic acids

Tetronic acids and β-keto-γ-butyrolactones are easily prepared by the zinc induced reaction of O-trimethylsilylated cyanohydrins and α-bromoesters.     

Transition Metal Ion-binding Properties of a 14-Membered N2O2S2- Macrobicyclic Ligand

The selective liquid–liquid extraction of various transition metal cations from the aqueous phase to the organic phase was carried out using a 14-membered N₂O₂S₂-macrobicycle. Metal picrates such as Pb²⁺, Co²⁺, Zn²⁺, Ni²⁺,Cu²⁺ and Cd²⁺ were used in this extraction studies. It was found that the ligand showed moderate selectivity towards Pb²⁺ only among the other metals. The extraction constant (log K _ex) was determined to be 13.8 for Pb²⁺ complex.     

Crystalline ordering in lattice models of hard rods with nearest neighbour attraction

Several lattice models for hard rods with attraction between neighbouring parallel rodes are considered. It is proved that the models for sufficiently low temperature and high fugacity exhibit a phase transition to an ordered crystalline structure. Nothing is proved about the existence of a liquid crystal state.     

Ferrocenyl compounds possessing protected phenol and thiophenol groups: Synthesis,X-ray structure,and in vitro biological effects against breast cancer

We have previously shown that conjugated ferrocenyl p-phenols show strong cytotoxic effects against both the hormone-dependent MCF-7 and hormone-independent MDA-MB-231 breast cancer cell lines, possibly via metabolic quinone methide (QM) formation. To further evaluate this proposed mechanism, we have created a series of ferrocenyl prodrugs containing methyl and acetyl-protected thio- and oxo-phenols: 2-ferrocenyl-1,1-bis(4-acetoxyphenyl)-but-1-ene (5), 2-ferrocenyl-1,1-bis(4-thioacetylphenyl)-but-1-ene (6), 2-ferrocenyl-1,1-bis(4-methoxyphenyl)-but-1-ene (7), and 2-ferrocenyl-1,1-bis(4-thiomethylphenyl)-but-1-ene (8), which might be activated by hydrolysis enzymes in situ. Only the acetoxy 5 displayed antiproliferative effects (IC₅₀ on MDA-MB-231 of 0.5 μM) while 6–8 act as pure estrogens (proliferative on MCF-7 and little to no effect on MDA-MB-231). The behaviour of 5 is similar to that previously found for the free phenol 2-ferrocenyl-1,1-di(4-hydroxyphenyl)-but-1-ene (2), indicating that 5 is metabolized in situ to 2, which could then undergo oxidative QM formation. The observation that the thioacetyl 6 is not cytotoxic suggests that the in situ oxidative chemistry of the putative ferrocenyl thiophenol is different from that of 2. Because p-thioquinone methides are practically unknown, the negative results for 6 further implicate the bioformation of the QM in the case of 2 and related compounds. The lack of cytotoxicity of 7 and 8 can be attributed to lack of efficient hydrolysis in situ. Estrogen receptor binding affinity studies for the compounds and the X-ray structure of 8 are also reported.