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International audience; A correlation between the second critical field of the helix to paramagnetic transition and the magnetic specific heat -peak was found in ZnCrAlSe spinel single crystals with =0.15, 0.23. The specific heat peak is anomalously sharp for all finite magnetic fields used here and this points to a first order magneto-structural transition (from cubic to tetragonal symmetry). The (T)-peak is increasingly suppressed as the external field increases. Approaching the Neel temperature , a broad ac-magnetic susceptibility peak is observed for zero dc-magnetic field. That peak does not show an energy loss and thus points towards a return to a second order type of transition. The magnetic contribution to the specific heat displays a sharp peak at and is maximal at the spin fluctuation temperature =34K. is related to the maximum of the magnetic susceptibility at =40K (at 50kOe) in the spin fluctuation region, as evidenced by the entropy exceeding 90% of the entropy calculated classically for the complete alignment of the Cr spins, (2-x)Rln(2S+1). The X-ray photoelectron spectroscopy (XPS) data indicate that Al-substitution does not affect Cr 3 electronic configuration.

International audience; The single crystals of Sb and V doped zinc chromium selenide spinel ZnCrSe were prepared by a chemical transport method and characterized by ESR spectroscopy in order to examine an effect of nonmagnetic antimony and magnetic vanadium on a properties of the system. For antimony admixtures the Neel temperature is very similar to that of the parent spinel ZnCrSe (22K). However, upon incorporating vanadium ions, the T temperature decreases down to 17.5K, determined for the maximum vanadium content (x=0.06). The temperature dependence of the ESR linewidth over paramagnetic region is interpreted by an occurence of spin-phonon interaction. The strong broadening linewidth together with its strong temperature dependence for vanadium doped ZnCrSe is explained by the complex paramagnetic relaxation model.

J Physiol Pharmacol. 2009 May;60 Suppl 1:85-94. Comparison of cellular and tissue transcriptional profiles in canine mammary tumor. Pawlowski KM, Krol M, Majewska A, Badowska-Kozakiewicz A, Mol JA, Malicka E, Motyl T. Department of Physiological Sciences, Faculty of Veterinary Medicine, Warsaw University of Life Sciences - SGGW, Poland. Tumor-derived cell lines are widely used as in vitro cancer models. Cell lines historically served as the primary experimental model systems for exploration of tumor cell biology and pharmacology. However, their ability to accurately reflect the phenotype and genotype of the parental histology remains questionable, given the prevalence of documented cell line-specific cytogenetic changes. Sometimes cell line studies are interpreted in the context of artifacts introduced by selection and establishment of cell lines in vitro. This complication has led to difficulties in the extrapolation of biology observed in cell lines to tumor biology in vivo. The aim of our study was to compare gene expression profiles in canine mammary tumor tissue and cell cultures derived from those tumors using cDNA microarrays. Tumors of two different origins were used; chondrosarcoma and adenocarcinoma and their primary cell cultures. It has been found that cell culture gene expression profiles closely resembled those of their corresponding in vivo tumor. In adenocarcinoma and chondrosarcoma only 6.0% and 2.7% of genes respectively, have shown significant difference in expression. In the most cases the difference concerned up-regulation of gene expression in cell lines, particularly genes involved in: protein metabolism and modification, signal transduction and nucleotide, nucleoside and nucleic acid metabolism. These experiments revealed that transcriptome of our primary cell culture corresponds to transcriptome of its parental tumor tissue and for this reason cell culture represents the reliable in vitro model for oncogenomic and pharmacogenomic studies. PMID: 19609017 [PubMed - in process]