New Phase in the Bi–Sr–Ca–Cu–O System

Cooling a melt of a Bi–Sr–Ca–Cu–O system (Bi:Sr:Ca:Cu = 4:3:3:4 or 2:2:2:4) from 1000°C-1050°C yielded crystals of a new red-colored nonsuperconducting phase, accompanying the superconducting 2212 and 2201 phases. Based on the EPR spectra, it was concluded that copper is univalent in this compound. The new phase has a composition Bi_2.2Sr_1.6Ca_1.3Cu₂Ox. The X-ray diffraction pattern has been indexed, and the unit cell parameters of the phase have been determined: space group P2/m, a = 12.93, b = 4.55, c = 10.94 ; = 102.72°.     

Nano-scale dissolution phenomena in Al–Cu–Mg alloys

Localized corrosion of aluminum alloys is a major issue worldwide and in spite of decades of work, several questions still remain unresolved. In this study we focus on key issues in the context of localized corrosion of Al–Cu–Mg/Al–Mg–Cu alloys that have not been adequately addressed. By careful electrochemical exposure along with high-resolution electron microscopy, we reveal that microstructural features down to a few nanometers in size can behave as unique electrochemical entities. In addition, not only is this critical to emerging damage accumulation models, but we also reveal that significant dissolution can occur at potentials below the breakdown potential of the bulk alloy. This work has potentially wide consequences in the interpretation of Al alloy corrosion and alloys design for corrosion resistance.     

Platinum–germanium ordering in UPtGe

The non-centrosymmetric structure of UPtGe was investigated by X-ray diffraction on both powders and single crystals: EuAuGe type, Imm2, a=432.86(5), b=718.81(8), c=751.66(9) pm, wR₂=0.0738 for 399 F² values and 22 variables. The platinum and germanium atoms form two-dimensional layers of puckered Pt₃Ge₃ hexagons with short PtGe intralayer distances of 252 and 253 pm. These condensed two-dimensionally infinite nets are interconnected to each other via weak PtPt contacts with bond distances of 300 pm. The two crystallographically independent uranium atoms are situated above and below the six-membered platinum–germanium rings. The U1 atoms have six closer germanium neighbors while the U2 atoms have six closer platinum neighbors. The group–subgroup relation with the KHg₂ type structure is presented.     

Reactive diffusion in W–Mo–Si thin films

This study reports the phase formation in the ternary thin films system Mo–W–Si. The metallic films were deposited onto Si (100) substrate by sputtering. Two kinds of samples were prepared, either by sequential deposition or by co-deposition. The phase formation was investigated by In situ X-ray diffraction measurements from 300 to 900 °C. The influence of the sample preparation, namely sequential deposition and co-deposition, on the mechanism of phase formation has been evidenced.     

Phase equilibria in the Sn–As–Ge and Sn–As–P systems

T–x diagrams of polythermal GeAs–SnAs, GeAs–Sn₄As₃ sections of the Sn–As–Ge system and Sn₄P₃–Sn₄As₃ section of the Sn–As–P system were constructed using the results of X-ray powder diffraction and differential thermal analyses. It was found that the section GeAs–Sn₄As₃ is not quasi-binary due to realization of four-phase peritectic transformation L + SnAs ? GeAs + Sn₄As₃ at the temperature of 834 K. The quasi-binary section GeAs–SnAs represents a phase diagram of the eutectic type with the following coordinates of eutectic reaction: temperature of the eutectic point is 840 K, and composition is 20 mol% GeAs. In the Sn–As–P system, the existence of the solid-solution range indicated as (Sn₄As₃) _x (Sn₄P₃)_1?x  was defined. The polythermal section Sn₄P₃–Sn₄As₃ is not quasi-binary due to the fact that in the composition range with a high content of tin arsenide discussed section intersects the peritectic part of the three-phase volume (L + SnAs + α) of the ternary diagram.     

Two new layered oxohalides in the system Cu–Yb–Te–O–Cl

Two complex lanthanide(III) transition metal(II) tellurium(IV) oxyhalides, Cu₃Yb₂(TeO₃)₄Cl₄ and Cu₃Yb₃(TeO₃)₄Cl₆ have been synthesized and the crystal structures were determined by single-crystal X-ray diffraction. Both compounds are layered with only weak connections in between the layers. The layers are made up of [YbO₈], [TeO₃] and [CuO_xCl_y] polyhedra. In both compounds the strong Lewis acid cations Yb³⁺ and Te⁴⁺ only form bonds to oxygen while Cu²⁺ form bonds to both oxygen and chlorine. This leads the Cl^? ions to be expelled from the bonding volumes of the crystal structures and protrude from the layers. Magnetic susceptibility measurements were performed on a powder sample of Cu₃Yb₂(TeO₃)₄Cl₄. The Curie–Weiss law found at low temperatures indicates a Curie–Weiss temperature of ca. ?5(1) K. However, indication for long-range magnetic ordering could not be observed down to 1.87 K. The two new phases are to the best of our knowledge the first containing all three of Cu, Yb and Te.     

Metal–base pairing in DNA

The use of DNA as a molecular wire in nanoscale electronic architectures would greatly benefit from its capability of sequence-specific self-assembly. Although single electrons and positive charges have been shown to be transmitted by natural DNA over a distance of several base pairs, the high ohmic resistance of unmodified oligonucleotides imposes a serious obstacle. Exchanging some or all of the Watson–Crick base pairs in DNA by metal complexes may solve this problem and evolve DNA-like materials with superior conductivity for future nano-electronic applications. The so-called metal–base pairs are formed from suitable transition metal ions and ligand-like nucleosides which are introduced into both of the two pairing strands by automated DNA synthesis. This review illustrates the basic concepts of metal–base pairing and highlights recent developments in the field.     

Sol–gel research in Italy

A short story of the research on sol–gel in Italy is given, and the evolution is presented and compared with the rest of the world in terms of number of publications, citations and patents. It is shown that both basic and applied research are active and effective in Italy.     

Liquid–liquid phase equilibrium in ternary immiscible Al–Bi–Sn melts

In this paper, the liquid-phase separation of ternary immiscible Al–Bi–Sn melts was studied with resistivity and thermal analysis methods at different temperatures. The resistivity–temperature curves appear anomalous and abrupt change as rising temperature, corresponding to the distinctive and low peak of melting process in the differential scanning calorimetry (DSC) curves, indicative of the occurrence of the liquid-phase separation. The anomalous behaviour of the resistivity temperature dependence is attributable to concentration–concentration fluctuations. The microheterogeneity–microhomogeneity transformation causes large fluctuations in concentration, which make the randomness and chaos of the atoms larger, leading to the greater impediment to electron movement and the sharp rise of resistivity. The addition of tin to the Al–Bi immiscible alloys decreases the monotectic reaction. It is concluded that concentration–concentration fluctuations are responsible for the anomalous behaviour of resistivity and DSC methods.     

Specific features of phase equilibriums in Ln–Ba–Fe–O systems

Formation of five-layered Ln_2–εBa_3+εFe₅O_15–δ phases [exhibiting nanoscale ordering with layer-by-layer location of the cations in the Ln–Ba–(Ln,Ba)–(Ln,Ba)–Ba–Ln perovskite-type structure] has occurred in the Ln–Ba–Fe–O (Ln = Y, Pr, Nd, Sm, Eu, and Gd) systems at 1100°С in air. Partial substitution of iron with cobalt (Ln_2–εBa_3+εFe_5–yCo_yO_15–δ, Ln = Nd, Sm, Eu) has stabilized formation of the ordered structure. The oxygen content in the complex oxides has been determined in air over a wide temperature range by means of high-temperature thermogravimetry and iodometric titration. The change in oxygen content with temperature for the phases with five-layered ordering was significantly smaller than for the disordered phases.     

Synthesis of quasi-crystalline phases in the Al–Cu–Fe–Cr system

Phase equilibria in the Al–Cu–Fe system alloyed with 5% Cr were studied. Based on the data of X-ray powder diffraction analysis, electron microscopy, and differential thermal analysis, the effect of temperature on i ? d phase transitions in alloys Al₆₅Cu₂₅Fe₅Cr₅ and Al₇₀Cu₂₀Fe₅Cr₅. In the Al–Cu–Fe–Cr system, multiphase structures were detected; these structures are mixtures of quasi-crystalline and approximant phases, the contents and morphologies of which depend on the composition of the initial mixture and the crystallization rate.     

Quantification of phytochelatins in plants by reversed-phase HPLC–ESI–MS–MS

An on-line HPLC–ESI–MS–MS method has been developed for determination of glutathione and phytochelatins (PC) in plant tissues. For sample pretreatment, dithiothreitol (DTT) must be added at the very beginning, as an anti-oxidant. Optimization of instrumental conditions i.e. composition of HPLC mobile phase, ionization efficiency of the electrospray interface, and MS–MS detection in the multiple ion-monitoring mode, are the central aspects of this work. A polystyrene-packed column was found to be superior to a standard silica-packed reversed-phase column. A concave quadratic gradient of ammonium formate buffer and acetonitrile was found to be optimum. The limits of quantitation were 0.2 mol kg^–1 plant tissue for glutathione and PC. The method has been applied to analysis of tissue samples from Vicia faba grown in Cd-containing nutrient solutions.Dedicated to the memory of Wilhelm Fresenius     

LC–ESI–MS Determination of Flupentixol in Human Plasma

Flupentixol and an internal standard, loperamide were extracted from human plasma by liquid–liquid extraction and analyzed on a Thermo Hypersil HyPURITY C18 column, with 10 mM ammonium acetate–acetonitrile–methanol (26:62:12, v/v/v) as mobile phase, coupled with electrospray ionization mass spectrometry (ESI–MS). The protonated analyte was quantified by selected-ion monitoring (SIM) with a quadrupole mass spectrometer in a positive-ion mode. The calibration curve was linear (r = 0.9990) over the concentration range: 0.039–2.5 ng mL^?1. Intra-day and inter-day precision (RSD%) were less than 13.05%. The established method was successfully applied for the determination of pharmacokinetics of flupentixol in human plasma.     

TG–DTG–DTA in studying white self-compacting cement mortars

Self-compacting cement mortars and concretes are characterized with an excellent workability and with high early strengths, which makes them suitable for elements in pre-cast concrete. Both the dense structure and the non-defected surface of self-compacting mixes are achieved by the incorporation of relatively large amounts of fine mineral additives and use of polycarboxylate admixtures. All these advantages determine the great potential for manufacturing of architectural elements and details. However, there exist many features in the structure-formation and the hardening of these systems. The authors investigate in this study the evolution of the process of curing and the crystal formation up to the 120th days of water-curing. Moreover, the effects of replacement of 10?wt% white cement with natural zeolite are studied. Special attention is paid to the thermal analysis through which one determines the effects of dehydration of the new-formed crystal hydrates, de-carbonization of carbonate-containing phases, and zeolite incorporation. Differences in the thermal behaviour of self-compacting mortars are compared with two types of referent samples. The thermal experiments were complemented with physical?Cmechanical and structural measurements, including mercury intrusion porosimetry, powder X-ray diffraction and scanning electron microscopy. Experiments and analysis, both determining the development of the microstructure, indicate the formation of a dense structure of white self-compacting mortars. This is achieved at the early age impeding the growth of new crystals. The incorporation of zeolite increases the early strengths of samples, thus making the structure denser, and completely blocking the water permeability. As the zeolite is a soft and ductile mineral, it can be expected that the volume deformations of microstructure of the zeolite-containing mortars, are reduced.     

LC–MS–MS Determination of Nikethamide in Human Plasma

A sensitive LC–MS–MS method with electrospray ionization has been developed for determination of nikethamide in human plasma. After addition of atropine as internal standard, liquid–liquid extraction was used to produce a protein-free extract. Chromatographic separation was achieved on a 150 mm × 2.1 mm, 5 μm particle, Agilent Zorbax SB-C₁₈ column, with 45:55 (v/v) methanol–water containing 0.1% formic acid as mobile phase. LC–MS–MS was performed in multiple reaction monitoring mode using target fragment ions m/z 178.8 → 107.8 for nikethamide and m/z 289.9 → 123.8 for the internal standard. Calibration plots were linear over the range of 20.0–2,000 ng mL^?1. The lower limit of quantification was 20.0 ng mL^?1. Intra-day and inter-day precisions were better than 4.2 and 6.1%, respectively. Mean recovery of nikethamide from human plasma was in the range 65.3–71.1%.     

Phase equilibria in the ternary system NaF–KF–CsF

The ternary eutectic system CsF–KF–NaF was studied by differential thermal analysis. The melting point and composition of the ternary eutectic were determined, and so was the boundary of the region of limited series of solid solutions within the composition triangle. The compositions of crystallizing phases were confirmed by X-ray powder diffraction analysis. The specific enthalpy of melting of the ternary eutectic was experimentally found.     

SPE–GC–MS Analysis of Chloroform in Drinking Water

In this paper we report a method based on solid-phase extraction (SPE) and subsequent analysis by gas chromatography combined with mass spectrometry for determination of chloroform in potable water. The affinity of chloroform for the resin enables almost complete recovery of the analyte. The analytical method proposed enables evaluation of chloroform levels down to 0.295 g L^–1. The procedure is characterized by lack of interferences, in fact the GC–MS analysis reveals the presence of only one peak, that of chloroform. Use of CDCl₃ as labelled internal standard also makes the procedure suitable for use as a reference analytical method for quantification of chloroform in drinking water.     

LC–ESI–MS Determination of Lovastatin in Human Plasma

A convenient, selective and sensitive liquid chromatographic-electrospary ionization mass spectrometry (LC–ESI–MS) method was developed and validated to determine lovastatin in human plasma. The analyte was extracted from human plasma samples by typical liquid–liquid extraction, separated on a C₁₈ column by using the mobile phase consisting of water–methanol (13:87, v/v). Simvastatin was used as the internal standard (IS). The method was linear within the range of 0.1–20 ng mL⁻¹. The lower limit of quantification (LLOQ) was 0.1 ng mL⁻¹. The intra- and inter-run precision, calculated from quality control (QC) samples was less than 10.2%. The accuracy as determined from QC samples was in the range of 99.3–102.9% for the analyte. The mean recoveries for lovastatin and IS were 84.8 and 88.0%, respectively. The method was successfully applied for evaluation of the pharmacokinetic of lovastatin in healthy volunteers.