A new low-temperature Tcr=101 K phase transition in (NH4)3H(SeO4)2 evidenced by single crystal ESR

Temperature ESR measurements on SeO₃ - radicals in (NH₄)₃H(SeO₄)₂ single crystals disclosed new ESR anomalies at T = 101 K. Below this temperature the hyperfine splitting becomes to be temperature averaged, ESR linewidth shows motional narrowing and an anomaly in forbidden transition intensity is observed. Also the dielectric measurements show an anomaly of the ε at this temperature. We suggest an existence of a new crystal phase VI below T_cr = 101 K with NH₄-groups ordering and slow SeO₄-group dynamics.     

Concentrations, sources, and spatial distribution of individual polycyclic aromatic hydrocarbons (PAHs) in agricultural soils in the Eastern part of the EU: Poland as a case study

Soils from agricultural areas receive unsatisfactory attention as regards the contamination with organic pollutants. To answer those needs the contents of the sixteen individual PAH compounds were determined (GC/MS technique) in agricultural soils in Poland. The samples (n = 216) were collected from the upper layer of arable land in the year 2005. Half of the samples represented typical rural areas, while the rest derived from the territories potentially subjected to the urban/industrial pressure of various intensity. The mean (geometric) content of individual compounds varied from 1 μg kg^− 1 for acenaphtylene to 55 μg kg^− 1 for fluoranthene with the highest contributions (11.6%-12.9%) of phenanthrene, fluoranthene and pyrene. Higher molecular weight PAHs (4 rings) were strongly linked mutually and with the ∑16PAHs. They contributed substantially (73%) to the overall content of PAHs, which implies domination of anthropogenic sources. The calculated molecular indexes suggest that most of those PAHs derive from the combustion of coal, the main energy source in Poland. Simultaneously, the concentrations of lower molecular weight compounds seem to reflect the background, “natural” PAH compounds, which represent mainly atmospherically distributed emission. The division of the samples into groups describing geographical regions and landscape type enabled evaluation of the spatial trends in contamination of soils with PAH compounds. The most pronounced effect of spatial parameters corresponded to PAHs > 4 rings, while lower molecular weight compounds showed more homogeneous concentration through the country.     

Biological activation of carbon filters

To prepare biological activated carbon (BAC), raw surface water was circulated through granular activated carbon (GAC) beds. Biological activity of carbon filters was initiated after about 6 months of filter operation and was confirmed by two methods: measurement of the amount of biomass attached to the carbon and by the fluorescein diacetate (FDA) test. The effect of carbon pre-washing on WG-12 carbon properties was also studied. For this purpose, the nitrogen adsorption isotherms at 77K and Fourier transform-infrared (FT-IR) spectra analyses were performed. Moreover, iodine number, decolorizing power and adsorption properties of carbon in relation to phenol were studied. Analysis of the results revealed that after WG-12 carbon pre-washing its BET surface increased a little, the pH value of the carbon water extract decreased from 11.0 to 9.4, decolorizing power remained at the same level, and the iodine number and phenol adsorption rate increased. In preliminary studies of the ozonation-biofiltration process, a model phenol solution with concentration of approximately 10mg/l was applied. During the ozonation process a dose of 1.64 mg O(3)/mg TOC (total organic carbon) was employed and the contact time was 5 min. Four empty bed contact times (EBCTs) in the range of 2.4-24.0 min were used in the biofiltration experiment. The effectiveness of purification was measured by the following parameters: chemical oxygen demand (COD(Mn)), TOC, phenol concentration and UV(254)-absorbance. The parameters were found to decrease with EBCT.     

Characterisation of colloidal and particulate organic carbon in freshwaters by thermal fluorescence quenching

Three-dimensional excitation-emission matrix (EEM) fluorescence with thermal quenching has been applied to raw and size-fractionated freshwaters. To size-fractionate organic matter, sequential filtration through mixed-ester-cellulose membrane filters with nominal pore size of 1.2, 0.1 and 0.025 microm were used. Humic-like fluorophores (peaks A and C) have been found to dominate EEMs of raw and all size fractions of studied waters. Peak A fluorescence intensity has been found to be more thermally sensitive than peak C fluorescence intensity. Humic-like fluorescence intensity was generally size independent, which indicated that it was present mainly in the smallest size fraction (<0.025 microm). This was confirmed by total organic carbon (TOC) measurements. Peak T (tryptophan-like) fluorescence, that is widely associated with biological activity, exhibited a greater thermal sensitivity of fluorescence intensity in the larger size fractions, demonstrating the presence of more than one fluorophore in different size fractions at this location in optical space. Thermal fluorescence quenching provides insights into organic matter variability and associated colloidal characteristics.     

Electron paramagnetic resonance evidence for direct co-ordination of copper(II) ions by acrylic resins containing amine groups

Summary E. p. r. and absorption spectra were used to indicate the formation of the complexes between copper (II) ions and acrylic resins containing oligoamines bound via amide bonds to acrylate units. The number of bound nitrogen atoms depends on the length of the amine chain attached to acrylamide unit.     

Dielectric response of polymer relaxors

Dielectric response of vinylidene fluoride type ferroelectric polymers is dominated by that of segmental motions in the amorphous phase in temperature range 200–300 K and contributions related to the local mode and ferroelectric–paraelectric transition in the crystalline phase of the polymer at higher temperatures. Diffuse and frequency-dependent dielectric anomaly observed in fast electron irradiated polyvinylidene fluoride-trifluoroethylene P(VDF/TrFE) has been related to relaxor-like behavior induced in the semicrystalline ferroelectric copolymers. As random field and the response of polar nanosize clusters determine the relaxor behavior the effects of disorder and fast electron irradiation (below and above T _C) on the three contributions to the dielectric response of PVDF, P(VDF/TrFE)(75/25) and P(VDF/TrFE)(50/50) are shown. The processes involved in radiation-induced functionalization of PVDF-type polymers are discussed on the basis of results of ESR, IR and Raman spectroscopy studies.     

A study of optical properties and annealing effect on the absorption edge of pristine- and iodine-doped polyazomethine thin films

Aromatic polyazomethine (PPI) thin film have been obtained by chemical vapor deposition (CVD) method, via polycondensation process and characterized by X-ray diffraction, AFM, FTIR and detailed UV–Vis–NIR studies. Optical transmission and fundamental reflectivity spectra of the film have been examined within the spectral range 200–2500 nm. The refractive index (n), film thickness (d) and parameters of the absorption edge i.e. the optical gap (E_G) and the Urbach energy (E_U) have been found for the PPI film before and after iodine (I₂) doping. Then the annealing effect (from 25 °C every 25 °C up to 225 °C) on the absorption edge have been investigated during “in situ” spectral measurements. Amorphous character of the films allowed us to obtain the E_G and E_U values, in the way typical for amorphous semiconductors. As a result of iodine doping, the energy gap of the PPI film (2.19 eV) distinctly reduces to 1.73 eV, due to the polaron states and, simultaneously, the Urbach energy decreases. Thermal stability of the pure PPI film, being the typical feature of polyazomethines, was confirmed, while after iodine doping the film turned out to be thermo-stable only below 100 °C; then the distinct changes of the optical gap and the Urbach energy, connected with the iodine releasing process, have been presented and discussed.     

Chemical characterization of urinary volatile compounds ofPeromyscus californicus,a monogamous biparental rodent

The urinary profiles of adult female and male California mice were examined to determine the volatile compounds that may affect reproduction. The urinary volatiles identified by gas chromatography-mass spectrometry (GC-MS) include ketones, pyrazines, alkanes, nitrile, and aldehyde. None of volatile compounds was specific to males or females. The concentration of urinary volatiles in pregnant and lactating females was significantly higher than in virgin females. Male urinary volatile concentrations were similar to those of pregnant and lactating females. The GC profiles of both sexes were distinguished by a high percentage (36%) of pyrazine derivatives that were also in unusually high concentrations. These compounds may play a wide-ranging role in the control of reproduction in the California mouse.     

Synthesis and properties of bismuth ferrite multiferroic flowers

Novel, flowerlike bismuth ferrite BiFeO₃ (BFO) multiferroic structures were prepared for the first time by means of microwave assisted hydrothermal synthesis. The flowers are composed of numerous petals formed by BFO nanocrystals and some amount of amorphous phase. The growth of the flowers begins from the central part of calyx composed of only few petals toward which subsequent petals are successively attached. The flowers exhibit enhanced magnetization due to size effect and lack of spin compensation in the spin cycloid. The dielectric properties of the flowers are influenced by BFO amorphous phase resulting in a broad dielectric permittivity maximum at 200–300 K and also by Polomska transition due to anomalous surface magnon damping above the temperature of 450 K. Possible applications of BFO flowerlike structures assume optoelectronic devices, excellent field emitters, effective solar cells, or catalyst supports.     

Improving the quality of life of caregivers of persons with spinal cord injury: A randomized controlled trial.

Objective: To assess the efficacy of two psychosocial interventions for caregivers of older persons with spinal cord injury (SCI). Design: A multisite, three-group, randomized controlled trial comparing two active intervention conditions with each other and to an information-only control group. One hundred seventy-three caregiver and care-recipient dyads were randomly assigned to one of three conditions: a caregiver-only treatment condition in which caregivers received a multicomponent intervention based on their risk profile; a dual-target condition in which the caregiver intervention was complemented by a treatment targeting the care recipient, designed to address both caregiver and care recipient risk factors; and an information-only control condition in which the caregiver received standard printed information about caregiving, SCI, and aging. Outcome Measures: A multivariate outcome comprised of six indicators linked to the goals of the interventions was the primary outcome of the study. The multivariate outcome included measures of depressive symptoms, burden, social support and integration, self-care problems, and physical health symptoms. Results: At 12 months, caregivers in the dual-target condition had improved quality of life as measured by our multivariate outcome when compared to the control condition. Using the dyad as the unit of analysis, the dual-target condition was superior to both the control condition and the caregiver-only condition in our multivariate outcomes analysis. Dyads enrolled in the dual-target condition had significantly fewer health symptoms than control condition and caregiver-only condition participants and were less depressed when compared to participants in the caregiver-only condition. In follow-up analyses we found that a higher proportion of caregivers in the dual-target condition had clinically significant improvements in depression, burden, and health symptoms when compared with the caregiver-only condition. Conclusion: Caregivers are in need of and can benefit from interventions that help them manage the medical and functional limitations of the care recipient. Intervention strategies that target both the caregiver and care recipient are particularly promising strategies for improving the quality of life of caregivers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)