Radon-222 and 226Ra concentrations in mineralized groundwaters of Gorzanów (Kłodzko Basin, Sudeten Mountains, SW Poland)

This work characterizes the occurrence of radionuclides ²²²Rn and ²²⁶Ra in the mineralized groundwaters of Gorzanów. The village is situated in the Sudeten Mountains, which are known in Poland for having increased concentrations of the aforesaid radionuclides in their groundwaters. However, in Gorzanów, the measured concentrations of ²²⁶Ra were low both in the reservoir rocks and mineralized waters. Consequently, the ²²²Rn concentration in the groundwaters also turned out to be low. The ²²⁶Ra content of these waters should mainly be associated with the dissolution of this nuclide, together with other main ions, at large depths, at slightly enhanced temperature. Radon-222, on the other hand, penetrates into the water during its outflow to the surface, in the zones of intensive friable deformations near fault zones. Thus, in the groundwaters of Gorzanów, the concentrations of these nuclides, subsequent in the uranium series, do not have a common genesis and they are not correlated with each other.     

Properties of a Ring Critical Pointas Measures of Intramolecular H-Bond Strength

Summary.  The topological parameters derived from the Bader theory such as the electron density and its Laplacian at the ring critical point (RCP) are analysed here as possible measures of the H-bond stength for intramolecular H-bonds. The parameters of RCP correlate well with the other properties of intramolecular H-bonds which are known as good measures of the H-bond strength. The calculations were performed on two samples of compounds with intramolecular H-bonds: the derivatives of malonaldehyde and the derivatives of o-hydroxybenzaldehyde. MP2 and HF calculations were carried out using a 6-311++G^** basis set. E-mail: slagra@krysia.uni.lodz.pl Received February 18, 2002; accepted (revised) May 27, 2002     

多晶Hg0.09Cd0.91Te薄膜的光电化学行为

富镉Hg_(1-x)Cd_xTe是一种新型的光电转换材料,已用于固体结太阳能光伏电池:ITO/CdS/Hg_(1-)Cd_xTe/Au。我们曾对Hg_(1-x)Cd_xTe的电沉积机理作过研究。最近我们用电沉积制备的Hg_(0.09)Cd_(0.91)Te多晶薄膜做成了液体结太阳能光电化学电池并观察到明显光电响应。     

Catalytic activity of silica in ozone formation in electrical discharges

The catalytic action of granular silica packing on ozone formation has been observed under discharge conditions. Using a glass ozonizer with a metal high-voltage electrode, at a frequency of 400 Hz it was possible to obtain much higher ozone concentrations in the presence q( silica than without packing, with the same total energy consumption. The dependence between ozone production and energy efficiency is considered, and conditions of the optimum ozonizer run are discussed. It is shown that in the all-glass ozonizer with a narrow discharge gap, the ozone concentration may be as high as 6.5% (ca. 130g O₃/m³) when silica packing is applied.     

Kinetics of thermal decomposition of Co3O4 powder and single crystals

Kinetics of thermal decomposition in vacuum of Co₃O₄ powder as well as single crystals has been investigated. Discrepancies with the results of previous authors have been discussed. Decomposition of Co₃O₄ proceeds through formation of a compact layer of CoO and hence diffusion is the rate-limiting factor. The experimental curves α(t) be described for 0.05 < α < 0.85 using a modified Ginstling-Brounshtein equation: 1 ? 2α/3 ? (1 ? α)^2/3 = ktⁿ where the activation energy varies with the degree of decomposition.     

Experimental and theoretical study on the olefin metathesis of alkenyl Baylis-Hillman adducts using second-generation Grubbs catalyst

[reaction: see text] We have investigated the olefin metathesis from alkenyl Baylis-Hillman adducts using second-generation Grubbs catalyst. In the experiment, the ring-closing metathesis (RCM) product could not be found, while the cross-metathesis (CM) products were found. The computational studies provided consistent explanations for the experimental result. The most limiting factor for the RCM process using second-generation Grubbs catalyst is caused by the high strain and steric effect in the metallacyclobutane intermediates.     

Manipulating the surface properties of polyacrylamide with nitrogen plasma

Polyacrylamide (PAL) was physically adsorbed onto a hydroxylated silicon surface to form a uniform PAL film and the up-top PAL thin film was treated by nitrogen (N₂) plasma for surface modification. The atomic composition of the modified surface of the PAL film adsorbed on silicon substrate was analyzed with Fourier Transform Infrared Spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The surface energy of PAL film was calculated from the data of contact angle of three-probe liquid. The FTIR results show an increase of peak intensity at 1214 cm⁻¹ (NH₂ stretch vibration) after the nitrogen plasma treatment, which confirms that the nitrogen was grafted to the PAL surface in the process of N₂-plasma treatment. The XPS results show that the ratio of relative intensity of N1s to O1s increases with increasing the plasma treatment time, which further affirms the formation of the amine groups on the PAL surface after the nitrogen plasma treatment. The surface tension increases with increasing the plasma grafting time. However, the surface energy decreases rapidly at the early stage when stored in air and approaches to an equilibrium value. It suggests that some physically-adsorbed ions and alkyl radicals on PAL surface can rapidly lose their activities. The increase of the surface tension of the plasma treated PLA films is due to the amine groups covalently grafted to PAL surface.     

Crystal structures and magnetic properties of two low-dimensional materials constructed from [Mn(III)(salen)H2O]+ and [M(CN)8](3-/4-) (M = Mo or W) precursors

The syntheses, X-ray structures, and magnetic behaviors of two new cyano-bridged assemblies, the molecular [Mn(III)(salen)H2O]3[W(V)(CN)8].H2O (1) and one-dimensional [Mn(salen)(H2O)2]2[[Mn(salen)(H2O)][Mn(salen)]2[Mo(CN)(8)]].0.5ClO4.0.5OH.4.5H2O (2), are presented. Compound 1 crystallizes in the monoclinic system, has space group P2(1)/c, and has unit cell constants a = 13.7210(2) A, b = 20.6840(4) A, c = 20.6370(2) A, and Z = 4. Compound 2 crystallizes in the triclinic system, has space group P, and has unit cell dimensions a = 18.428(4) A, b = 18.521(3) A, c = 18.567(4) A, and Z = 2. The structure of 1 consists of the asymmetric V-shaped Mn-NC-W-NC-Mn-O(phenolate)-Mn molecules, where W(V) coordinates with [Mn(salen)H2O] and singly phenolate-bridged [Mn(salen)H2O]2 moieties through the neighboring cyano bridges. The [W(V)(CN)8]3- ion displays distorted square-antiprism geometry. The structure of 2 consists of the cyano-bridged [Mn3(III)Mo(IV)]n- repeating units linked by double phenolate bridges into one-dimensional zigzag chains. The Mn(III) centers are bound to Mo(IV) of square-antiprism geometry through the neighboring cyano bridges. The magnetic studies of 1 reveal the antiferromagnetic intramolecular interactions through the CN and phenolate bridges and the relatively weak intermolecular interactions. Compound 1 becomes antiferromagnetically ordered below TN = 4.6 K. The presence of the magnetic anisotropy is documented with the MH measurements carried out for both polycrystalline and single-crystal samples. At T = 1.9 K, the spin-flop transition is observed in the field of 18 kOe applied parallel to the bc plane, which is the easy plane of magnetization. Field dependence of magnetization of 1 shows field-induced metamagnetic behavior from the antiferromagnetic ground state of ST = 3/2 to the state of ST = 5/2. The magnetic properties of 2 indicate a weak antiferromagnetic interaction between Mn(III) centers in double-phenolate-bridged [Mn(III)(salen)]2 dinuclear subunits and a very weak ferromagnetic interaction between them through the diamagnetic [Mo(IV)(CN)8]4- spacer.     

Matrix separation of palladium and iridium by the cellulose anion exchanger Cellex T and the subsequent determination of palladium at theμg/g-level

The preconcentration and separation of palladium and iridium from base metals is studied with cellulose (Cellex T) and styrene-divinylbenzene (Varion AT 400) anion exchangers. In spite of lower capacity of Cellex T to chloride complexes of Pd and Ir, it allowed to get a higher preconcentration factor. Yields of 92–99% are achieved for Pd and 96–97% for Ir from the solutions containing great excess of base and heavy metals. Graphite furnace atomic absorption spectrometry is used for the final measurements. The procedure has been applied to the determination of palladium in natural samples.     

Cis-coordination of the chromate anions in helical Co/Ni block-type polymeric systems. Structural and spectroscopic characteristics of catena(μ-CrO4-O,O′)[Co(HIm)3H2O] and catena(μ-CrO4-O,O′)[Co0.43Ni0.57(HIm)3H2O]

Two polymeric complexes: catena(μ-CrO₄-O,O′)[Co(HIm)₃H₂O] (1) and catena(μ-CrO₄-O,O′)[Co_0.43Ni_0.57(HIm)₃H₂O] (2) (where HIm=imidazole) with a cis-bridging coordination mode of the CrO₄ ²⁻ anion have been synthesized and characterized by X-ray and spectroscopic methods. These crystals were isolated from nine systems of varying reagent molar ratios and three excluding anions: Cl⁻, NO₃ ⁻ and SO₄ ²⁻ exclusively as mer [M(HIm)₃O₃]-type isomers. The unit cell of these isostructural complexes (monoclinic crystal system P2₁ /n) contains two independent helixes, left- and right handed, stabilized by intrahelical and interhelical hydrogen bonding and π–π interaction between pairs of the imidazole rings from neighbouring helixes. The Raman spectra at 77 K of 1 and 2 deconvoluted into lorentzian components revealed the block-type polymeric structure of the complexes. Moreover, the solution studies at millimolar concentrations of 1 and 2 indicated their complete decomposition in water. Four K electronic spectral analysis of the crystals (band deconvolution into gaussian components) enhanced with the data obtained in the polarized light allowed for assignment of the bands to the respective d–d transition (D_4h symmetry). It was found that the metallic centres are independently absorbing species, which supports the suggestion of a block-type structure of the polymers. The respective crystal field parameters for Co and Ni were calculated.