Close-packed monolayers of charged Janus-type nanoparticles at the air-water interface

Two DNA-block copolymers, poly(caprolactone)-DNA and poly(methyl metacrylate)-DNA, were synthesized by conjugation of a short single strand of DNA (12 or 22 mer) to a single reactive group at one end of the synthetic polymer. These polymers self-assemble in water, without the need of any cosolvent, forming micelle-like aggregates that were imaged by TEM. The solution behavior of the bioconjugated polymers was investigated by surface tension measurements. In the direction of dilution, the surface tension was measured using a down-scaled Wilhelmy plate method. To proceed in the reverse direction (concentration), we measured the surface tension of a sessile drop during its evaporation. This latter method was firstly validated using ionic and non-ionic surfactants, including polymeric surfactants. It was then applied to investigate the unimer to micelles transition of the DNA-block copolymers. In all cases, a reversible transition was observed demonstrating the existence of a critical micellar concentration, close to 0.01 mmol L⁻¹ for all the conjugates. The CMC was only slightly influenced by the length of the hydrophilic DNA block.     

The synthesis of new potential photosensitizers. 1. Mono-carboxylic acid derivatives of tetraphenylporphyrin

Abstract  

A series of mono-alkylcarboxylic acid derivatives of tetraphenylporphyrin have been prepared. All the porphyrins were completely characterized by use of mass, ¹H NMR, UV–visible, and fluorescence spectroscopy. Experimental log P were determined by use of reversed-phase thin-layer chromatography with use of log P _Rekker. These porphyrins are potential photosensitizers in photodynamic therapy.     

One-Pot Synthesis and Applications of N-Heteroaryl Iodonium Salts

An efficient one-pot synthesis of N-heteroaryl iodonium triflates from the corresponding N-heteroaryl iodide and arene has been developed. The reaction conditions resemble our previous one-pot syntheses, with suitable modifications to allow N-heteroaryl groups. The reaction time is only 30 min, and no anion exchange is required. The obtained iodonium salts were isolated in a protonated form, these salts can either be employed directly in applications or be deprotonated prior to use. The aryl groups were chosen to induce chemoselective transfer of the heteroaryl moiety to various nucleophiles. The reactivity and chemoselectivity of these iodonium salts were demonstrated by selectively introducing a pyridyl moiety onto both oxygen and carbon nucleophiles in good yields.     

Analytical protocol for investigation of zinc speciation in plant tissue

A specific procedure is proposed for investigating the chemical speciation of zinc (Zn) in plant tissues, viz., the extraction of Zn compounds from Plantago lanceolata L. followed by the chromatographic separation and inductively coupled plasma mass spectrometry (ICP-MS) identification of these compounds. In order to separate the Zn compounds, both size-exclusion (SEC) and ionexchange liquid chromatography (IC) were used in direct sequential and reverse sequential modes. In the direct sequential mode, the entire extract undergoes SEC separation and then the individual fractions are injected onto the ion-exchange column. The molecular size distribution is evaluated by SEC coupled on-line to the UV detector. In the reverse sequential mode, the entire extract undergoes the ion-exchange chromatographic separation and then the individual fractions are injected onto the size-exclusion column. The identification of Zn incorporated into the compounds is further performed using ICP-MS. This procedure is particularly useful in speciation studies when identification of the individual components of the element is problematic due to the lack of suitable standard substances, as is the case for Zn compounds. The proposed procedure facilitates assignment of the signals to the individual components of the fractions for both types of chromatography, thus rendering the chemical speciation of Zn possible when the lack of suitable standard substances impedes the identification of individual components.     

Promoted ternary CuO-ZrO2-Al2O3 catalysts for methanol synthesis

Ternary CuO-ZrO₂-Al₂O₃ catalysts promoted by palladium or gold were prepared and tested in CO hydrogenation reaction at 260°C under elevated pressure (4.8 MPa). The promotion effect of palladium or gold addition on the physicochemical and catalytical properties of CuO-ZrO₂-Al₂O₃ catalysts in methanol synthesis (MS) was studied. The catalysts were characterized by BET, XRD, TPR-H₂, TPD-NH₃ methods. The BET results showed that the ternary system CuO-ZrO₂-Al₂O₃ had the largest specific surface area, cumulative pore volume and average pore size in comparison with the promoted catalysts. The yield of methanol can be given through the following sequence: 5%Pd/CuO-ZrO₂-Al₂O₃ > CuO-ZrO₂-Al₂O₃ > 2%Au/CuO-ZrO₂-Al₂O₃. We also found that the presence of gold or palladium on catalyst surface has strong influence on the reaction selectivity. The high selectivity of gold doped ternary catalyst is explained by the gold-oxide interface sites created on the catalyst surface and the acidity of those systems. The higher selectivity to methanol in the case of the palladium catalyst is explained by the spillover effect between Pd and CuO.      

Structure and thermal properties of the fritted glazes in SiO<Subscript>2</Subscript>–Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–CaO–MgO–Na<Subscript>2</Subscript>O–K<Subscript>2</Subscript>O–ZnO system

In this work, the structure and thermal properties of aluminosilicate fritted glazes in SiO₂–Al₂O₃–CaO–MgO–Na₂O–K₂O–ZnO system with (4.0 mol%) and without addition of ZnO were examined by GIXRD, FTIR, MAS-NMR and thermal methods (DTA, DIL). It has been found that the all experimental glazes are amorphous material (transparent glazes). On the base of spectroscopic investigations, it was found that zinc ions exist in the network glazes in the octahedral coordination—Zn²⁺ ions play a network modifier role in structure of glazes. An analysis of the data obtained from thermal tests showed that addition of ZnO into chemical composition results in decrease in glass transition temperature value (T _g) for all glazes (DTA, DIL). The coefficient of thermal expansion (α) is decreased as the whole measurement range for one series of fritted glazes.     

Facile Synthesis of bis‐α‐Aminoalkylphosphinates

Herein we report a facile synthesis of esters of bis‐α‐aminoalkylphosphinic acids obtained by an addition of Cbz‐protected phosphinic analogues of amino acid methyl esters to an appropriate imine in refluxing benzene. Complete deprotection of the esters could be achieved in one step by the action of 30% HBr in acetic acid.     

On characterizations of multiwavelets in

We present a new approach to characterizing (multi)wavelets by means of basic equations in the Fourier domain. Our method yields an uncomplicated proof of the two basic equations and a new characterization of orthonormality and completeness of (multi)wavelets.