A 2D coordination polymer with canted ferromagnetism constructed from ferromagnetic [Ni(II)Co(II)] nodes

A bimetallic coordination polymer, infinity (2)[{LNi (II)Co (II)}(dca) 2], has been constructed from heterobinuclear [Ni (II)Co (II)] nodes and dicyanamido spacers [L (2-) is the dianion of the Schiff base resulting from the 2:1 condensation of 3-methoxysalicyladehyde with 1,3-propanediamine; L (2-) = N, N'-propylenebis(3-methoxysalycilideneiminato)]. The intranode Co (II)-Ni (II) interaction was found to be ferromagnetic because of the orthogonality of the magnetic orbitals. Below 12 K, the onset of the canted ferromagnetic ordering is observed.     

Detection of negative molecular ions in acrylic acid plasma: some implications for polymerization mechanisms

There is much scientific and commercial interest in plasma polymers to modify surface chemistry. To date, only neutral and positively charged species have been detected in the commonly applied acrylic acid plasma. Using time-averaged negative ion mass spectrometry, we demonstrate that large, negatively charged species exist in the plasma, contrary to previous studies that detected only neutral and positive species. We briefly outline how negative molecules may contribute to the deposition of plasma polymer in the acrylic acid system.     

Archaeometrical studies of Greek and Roman silver coins

Quantitative analyses of various silver coins from the first century BC, found on current Romanian territory (Thasian tetradrachmae, Apollonia and Dyrrachium drachmae, Roman republican denarii) were performed using PIXE (3 MeV external proton beam) and XRF (1.1 GBq²⁴¹Am source). The elemental analysis provided evidence of a great variety of monetary alloys and helped Romanian archaeologists to classify the coins, in terms of their provenance, as originals, copies or imitations minted in different areas of the Balkan-Carpathian region.     

Determination of131I,134Cs,137Cs in plants and cheese after Chernobyl accident in Roumania

Various samples from the south-east region of Roumania/greens, fodder, cheese/were analyzed for¹³¹I,¹³⁴Cs and¹³⁷Cs concentrations in May and July 1986 by -ray spectrometry. The concentrations are reported in nCi. kg^–1 wet weight. For greens, a considerable decrease was observed for¹³¹I/to 3.0–7.0 nCi. kg^–1/,¹³⁴Cs/to 0.5–2.0 nCi.kg^–1/ and¹³⁷Cs /to 1.0–4.0 nCi. kg^–1/ from the first half /5–15 May/ till the end of May 1986. For cheese, maximum values were measured between 5 and 15 May /sheep cottage cheese: 500–800 nCi.kg^–1 for¹³¹I, 25–50 nCi. kg^–1 for¹³⁴Cs, 40–80 nCi. kg^–1 for¹³⁷Cs/; at the beginning of July a considerable decrease /to 5–10 nCi. kg^–1 for¹³¹I, 1.2–2.0 nCi.kg^–1 for¹³⁴Cs, 2.2–3.0 nCi. kg^–1 for¹³⁷Cs/ was observed. In autumn 1986 a small increase up to 2.0–3.0 nCi. kg^–1 for¹³⁴Cs and 3.4–5.0 nCi. kg^–1 for¹³⁷Cs /in November/ was reported. The population's internal possible contamination was strongly limited by the authorities' severe control of the food-stuff.     

Direct determination of mitoxantrone and its mono- and dicarboxylic metabolites in plasma and urine by high-performance liquid chromatography

The simultaneous isolation and determination of mitoxantrone (Novantrone) and its two known metabolites (the mono- and dicarboxylic metabolites) were carried out using a high-performance liquid chromatographic (HPLC) system equipped with an automatic pre-column-switching system that permits drug analysis by direct injection of biological samples. Plasma or urine samples were injected directly on to an enrichment pre-column flushed with methanol-water (5:95, v/v) as the mobile phase. The maximum amount of endogenous water-soluble components was removed from biological samples within 9 min. Drugs specifically adsorbed on the pre-column were back-flushed on to an analytical column (Nucleosil C18, 250 X 4.6 mm I.D.) with 1.6 M ammonium formate buffer (pH 4.0) (2.5% formic acid) containing 20% acetonitrile. Detection was effected at 655 nm. Chromatographic analysis was performed within 12 min. The detection limit of the method was about 4 ng/ml for urine and 10 ng/ml for plasma samples. The precision ranged from 3 to 11% depending on the amount of compound studied. This technique was applied to the monitoring of mitoxantrone in plasma and to the quantification of the unchanged compound and its two metabolites in urine from patients receiving 14 mg/m2 of mitoxantrone by intravenous infusion for 10 min.     

Linker depletion for missing cluster defects in non-UiO metal–organic frameworks

Defect engineering is a valuable tool to tune the properties of metal–organic frameworks. However, defect chemistry remains still predominantly limited to UiO-type MOFs. We describe the preferential formation of missing cluster defects in heterometallic titanium–organic frameworks of the MUV-10 family when synthesised in sub-stoichiometric linker conditions. Our results show the value of integrating experimental work, computational modelling and thorough characterization in rationalizing the impact of defects over the porosity and structure of this family of materials. Correlation of experiment with computational models reveals the dominance of missing cluster vacancies in the pore size distribution of defective MUV-10. These same models were used to investigate the correlation of defects by synchrotron X-ray diffraction. The diffraction at low reflection angles is dominated by diffuse scattering that is indicative of short-range order and cannot be indexed to the defective structural models generated. In addition to the low atomic scattering factor of titanium, these results confirm the need for high-resolution electron microscopy methods for modelling nanoscale disorder in titanium MOFs.

Synthesis of MUV-10 in sub-stoichiometric linker conditions favours the formation of missing cluster vacancies for direct impact in their porosity.     

Shear and dielectric responses of propylene carbonate, tripropylene glycol, and a mixture of two secondary amides

Propylene carbonate and a mixture of two secondary amides, N-methylformamide and N-ethylacetamide, are investigated by means of broadband dielectric and mechanical shear spectroscopy. The similarities between the rheological and the dielectric responses of these liquids and of the previously investigated tripropylene glycol are discussed within a simple approach that employs an electrical circuit for describing the frequency-dependent behavior of viscous materials. The circuit is equivalent to the Gemant-DiMarzio-Bishop model, but allows for a negative capacitive element. The circuit can be used to calculate the dielectric from the mechanical response and vice versa. Using a single parameter for a given system, good agreement between model calculations and experimental data is achieved for the entire relaxation spectra, including secondary relaxations and the Debye-like dielectric peak in the secondary amides. In addition, the predictions of the shoving model are confirmed for the investigated liquids.     

Thermal and microstructural analysis of Cu(II) 2,2′-dihydroxy azobenzene and thin films deposition by MAPLE technique

A newly synthesized copper-complex exhibiting nonlinear optical properties, crystalline nature, and generating interest as a material for non-linear optical applications was investigated. As thermal stability studies are indispensable before attempting any laser-assisted processing experiments, the thermal behavior of 2,2′-dihydroxy azobenzene with Cu²⁺ cations that are found to organize themselves as non-central symmetric crystallites, was investigated. The thin films were deposited on silicon substrates by matrix-assisted pulsed laser evaporation using a Nd:YAG laser working at 266 and 355 nm. Thermal analysis of the bulk compound indicates a higher thermal stability in argon flow when compared to the air atmosphere; as well, since, the adhesion of the compound onto the substrate enhances the bonding, the thermal stability of the Cu complex increases. Fourier transform infrared spectroscopy, atomic force microscopy, scanning electron microscopy, spectroscopic ellipsometry, and ultraviolet–visible spectroscopy investigations were also performed.     

Existence d'isomeres e et z d'ylures de cycloimmonium

E and Z isomers of p-nitrobenzoyl, 4-p-tolyl[1-2-4]triazolum methylide 5b and p-nitrobenzoyl, 4-p-phenyl[1-2-4]triazolium methylide 5e, have been characterised.