tert-Butylzinc hydroxide as an efficient predesigned precursor of ZnO nanoparticles

The reaction of (t)Bu(2)Zn with water was investigated which led to isolation of the novel hexameric tert-butylzinc hydroxide. The resulting zinc hydroxide cluster appears to be an ideal predesigned single-source precursor which decomposes smoothly in one step at only ca. 120 °C into ZnO nanoparticles.     

Platinum(IV) coordination compounds containing 5-methyl-1,2,4-triazolo[1,5-a]pyrimidin-7(4H)-one as nonleaving ligand. Molecular and cytotoxicity in vitro characterization

Novel platinum(IV) coordination compounds with 5-methyl-1,2,4-triazolo[1,5-a]pyrimidin-7(4H)-one (HmtpO): cis-trans-[PtCl(2)(OH)(2)(NH(3))(HmtpO)] (1), cis-trans-[PtCl(5)(HmtpO)][(CH(3))(2)NH(2)] (2) have been prepared and structurally characterized by spectroscopic methods ((1)H, IR and X-ray crystallography (2)). The X-ray results indicate that the local geometry around the platinum(IV) centre approximates a typical octahedral arrangement with nitrogen atom N3 of the HmtpO and three chloride atoms in equatorial positions. The remaining two axial positions are occupied by two chlorides. The preliminary assessment of antitumor properties of (1) was performed as an in vitro antiproliferative activity against HL-60 human acute promyelocytic leukemia and HCV29T bladder cancer. The cis-trans-[PtCl(2)(OH)(2)(NH(3))(HmtpO)] (1) exhibits higher cytotoxic activity against HL-60 (IC(50)=6.4 μM) than cisplatin.     

Redox Active Dipyrromethene?Cu(II) Monolayer for Oriented Immobilization of His‐Tagged RAGE Domains – the Base of Electrochemical Biosensor for Determination of Aβ16–23′

The new system which consists of the thiol derivative of dipyrromethene–Cu(II) complex created on the surface of a gold electrode was applied for the first time for oriented immobilization of selected His‐tagged domains of a receptor for advanced glycation endproducts (RAGE). Cyclic voltammetry (CV), Osteryoung square‐wave voltammetry (OSWV), electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM) were used for characterization of the redox active sensing layer. The biosensor proposed was applied for determination of Aβ_16–23′ peptide. In its presence, a decrease of the maximum Cu(II) redox current was observed. These values correlated linearly with the Aβ_16–23′ concentration in the range 0.001–1.000 µM. The presence of diluted human plasma has no influence on the sensor responses.     

Hardy inequalities resulted from nonlinear problems dealing with A-Laplacian

We derive Hardy inequalities in weighted Sobolev spaces via anticoercive partial differential inequalities of elliptic type involving A-Laplacian ?Δ _A u = ?divA(?u) ≥ Φ, where Φ is a given locally integrable function and u is defined on an open subset \({\Omega \subseteq \mathbb{R}^n}\) . Knowing solutions we derive Caccioppoli inequalities for u. As a consequence we obtain Hardy inequalities for compactly supported Lipschitz functions involving certain measures, having the form $$\int_\Omega F_{\bar{A}}(|\xi|) \mu_1(dx) \leq \int_\Omega \bar{A}(|\nabla \xi|)\mu_2(dx),$$ where \({\bar{A}(t)}\) is a Young function related to A and satisfying Δ′-condition, while \({F_{\bar{A}}(t) = 1/(\bar{A}(1/t))}\) . Examples involving \({\bar{A}(t) = t^p{\rm log}^\alpha(2+t), p \geq 1, \alpha \geq 0}\) are given. The work extends our previous work (Skrzypczaki, in Nonlinear Anal TMA 93:30–50, 2013), where we dealt with inequality ?Δ _p u ≥ Φ, leading to Hardy and Hardy–Poincaré inequalities with the best constants.     

Influence of crosslinker and ionic comonomer concentration on glass transition and demixing/mixing transition of copolymers poly(N-isopropylacrylamide) and poly(sodium acrylate) hydrogels

Hydrogels based on N-isopropylacrylamide and sodium acrylate as ionic comonomer were synthesized by free radical polymerization in water using N,N′-methylenebisacrylamide as crosslinker and ammonium persulfate as initiator. The glass transition of dried copolymers poly(N-isopropylacrylamide) (PNIPA) and poly(sodium acrylate) (SA) gels and demixing/mixing transition of PNIPA-SA hydrogels swollen with increasing amounts of water were studied using conventional differential scanning calorimetry. In the crosslinked polymers, the glass transition linearly increases, and the transition range becomes broader, with increasing crosslinker content. Increasing content of ionic comonomer also produces an increase of glass transition temperature, which moves to higher temperatures with higher sodium acrylate fraction. The influence of chemical structure of PNIPA-SA hydrogels on the lower critical solution temperature (LCST) of PNIPA-SA/water mixtures during heating and cooling was quantified as function of the content of the crosslinker and the ionic comonomer, as well as water content of the hydrogel in the range from 95 to 70 wt%. At parity of water content, the LCST occurs at higher temperatures for gels containing higher amounts of sodium acrylate. Similarly, the introduction of N,N′-methylenebisacrylamide causes an increase of the LCST, which grows with increasing of crosslinking degree of the hydrogel.     

Calorimetric and thermal analysis studies on the influence of waste aluminosilicate catalyst on the hydration of fly ash–cement paste

Binders containing large amounts of cement substitutes have been a subject of interest for many years because of the possibility to reduce the amount of cement in concrete, and in consequence decrease negative influence of cement production on natural environment. In this work, studies related to hydration of binders where 80 % of cement was substituted by blended pozzolana were carried out. The aim of this work was to investigate activation of fly ash–cement system by addition of spent aluminosilicate catalyst, using calorimetry and thermal analysis as main methods of investigations. It was demonstrated that spent fine-grained fluidised catalytic cracking catalyst acts acceleratingly on early hydration of binder. It seems to be beneficial to use up to 10 mass% of this spent catalyst. Higher amounts may cause changes in the mechanism of early hydration. Because Ca(OH)₂ in such systems is quickly consumed due to pozzolanic reaction it seems beneficial to modify composition of binders by introducing additional amounts of Ca(OH)₂ or cement.     

Complexes of transition metals bonded to silica via β-diketonate groups — synthesis, structure, and catalytic activity

Transition metal complexes bonded to silica via silanes with β-diketonate groups can be used as packings for complexation gas chromatography or as immobilized homogenous metal complex catalysts. On basis of elemental analysis and the determination of surface area, possible structures of the complexes formed on the silica surface have been proposed. The possibility of using the immobilized complexes as catalysts has been indicated. Especially nickel complexes were taken into consideration. These immobilized complexes were used previously as packings for complexation gas chromatography.     

Electron capture by pentafluoronitrobenzene and pentafluorobenzonitrile

Electron attachment to pentafluorobenzonitrile (C(6)F(5)CN) and pentafluoronitrobenzene (C(6)F(5)NO(2)) is studied in the energy range 0-16 eV by means of a crossed electron-molecular beam experiment with mass spectrometric detection of the anions. We find that pentafluoronitrobenzene exclusively generates fragment anions via dissociative electron attachment (DEA), while pentafluorobenzonitrile forms a long lived parent anion within a narrow energy range close to 0 eV and additionally undergoes DEA at higher energies. This is in contrast to the behaviour of the non-fluorinated analogues as in nitrobenzene the non-decomposed anion is formed while in benzonitrile only DEA is observed. The associated reactions involve simple bond cleavages but also complex unimolecular decompositions associated with structural and electronic rearrangement also resulting in the deterioration of the cyclic structure.     

Cylindrical projection of electrostatic potential and image analysis tools for damaged DNA: the substitution of thymine with thymine glycol

Changes of electrostatic potential around the DNA molecule resulting from chemical modifications of nucleotides may play a role in enzymatic recognition of damaged sites. Effects of chemical modifications of nucleotides on the structure of DNA have been characterized through electronic structure computations. Quantum mechanical structural optimizations of fragments of five pairs of nucleotides with thymine or thymine glycol were performed at the density functional level of theory with a B3LYP exchange-correlation functional and 6-31G(d,p) basis sets. The electrostatic potential (EP) around DNA fragments was projected on a cylindrical surface around the double helix. The 2D maps of EP of intact and damaged DNA fragments were compared using image analysis methods to identify and measure modifications of the EP that result from the occurrence of thymine glycol. It was found that distortions of phosphate groups and displacements of the accompanying countercations by up to approximately 0.5 angstroms along the axis of DNA are clearly reflected in the EP maps. Modifications of the EP in the major groove of DNA near the damaged site are also reported.