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Single crystal of Eu3+-doped cadmium molybdate (Cd0.9268▯0.0244Eu0.0488MoO4, where ▯ denotes cationic vacancies) has been successfully grown by the Czochralski method in air and under 1 MPa. X-ray diffraction analysis indicates that as-grown single crystal exhibits tetragonal scheelite-type structure (a = b = 5.16188(14) A; c = 11.2080(5) A; space group I41/a). Eu3+ ions do not show long-range order and they are randomly distributed in CdMoO4 framework substituting Cd2+ ones. UV–vis diffuse reflectance measurements revealed very close optical band gap (Eg) values, i.e. ∼1.74 eV along [100] and [001] crystallographic directions that are twice smaller than Eg of microcrystalline pure CdMoO4 as well as powder Eu3+-doped single crystal. Magnetic and electrical studies of Eu3+-doped cadmium molybdate single crystal showed a paramagnetic and n-type semiconducting behaviour with the metal-insulator transition above 350 K along both crystallographic directions. Dielectric results analysis using the Cole-Cole fit function revealed that the dipole relaxation process has different time scale depending on the crystallographic direction and exhibits Arrhenius temperature dependence for both studied directions. This fact is accompanied by the colossal dielectric permittivity with er > 8⋅103. The above results are considered in the framework of narrow europium multiplets of energy comparable to thermal energy.

Gd3+-doped lead molybdato-tungstates with the chemical formula of Pb1−3x □ x Gd2x (MoO4)1−3x (WO4)3x (where x = 0.0455, 0.0839, 0.1430, corresponding to 9.53, 18.32, 33.37 mol% of Gd3+, respectively, as well as □ denotes cationic vacancies) were successfully synthesized via combustion route. The XRD and SEM results confirmed the formation of single-phase, tetragonal scheelite-type materials (space group I41/a) with the uniform, spherical and oval grains ranging from 5 to 20 µm. Individual grains are strongly agglomerated into big clusters with the size even above 50 µm. The magnetic measurements as well as the Brillouin fitting procedure showed paramagnetic state with characteristic superparamagnetic-like behaviour and the short-range ferromagnetic interactions. The electrical and broadband dielectric spectroscopy studies revealed insulating properties with the residual electrical n-type conduction of 2×10−9 S/m and low energy loss (tanδ ≈ 0.01) below 300 K. Dielectric analysis showed that no dipole relaxation processes in the Gd3+-doped materials were observed. A fit of dielectric loss spectra of Gd3+-doped samples by sum of the conductivity and the Havriliak-Negami, Cole-Cole, and Cole-Davidson functions confirmed this effect.

The electrical measurements of ZnSb2􀀀xTaxO6 phases with x = 0:0; 0:1; 0:25; 0:75; 1:6 have revealed insulating behavior with strongly decreasing electrical conductivity when tantalum x content is increased. As a consequence, high values of relative permittivity "r and loss tangent tan( ) were observed, that decreased with increase of temperature and frequencies, for samples with low Ta content, below x = 0:75. In turn, for samples richer in tantalum, "r reaches 14, and tan( ) becomes as low as 0.02 for x = 1:6. These effects have been interpreted either by the framework of the relaxation processes, or by the spatial charge polarization leading to the low energy loss of materials.

The new series of single-crystalline chromium selenides, Ta-doped ZnCr2Se4, was synthesised by a chemical vapour transport method to determine the impact of a dopant on the structural and thermodynamic properties of the parent compound. We present comprehensive investigations of structural, electrical transport, magnetic, and specific heat properties. It was expected that a partial replacement of Cr ions by a more significant Ta one would lead to a change in direct magnetic interactions between Cr magnetic moments and result in a change in the magnetic ground state and electric transport properties of the ZnCr2−xTaxSe4 (x = 0.05, 0.06, 0.07, 0.08, 0.1, 0.12) system. We found that all the elements of the cubic system had a cubic spinel structure; however, the doping gain linearly increased the ZnCr2−xTaxSe4 unit cell volume. Doping with tantalum did not significantly change the semiconductor and magnetic properties of ZnCr2Se4. For all studied samples (0 ≤ x ≤ 0.12), an antiferromagnetic order (AFM) below TN~22 K was observed. However, a small amount of Ta significantly reduced the second critical field (Hc2) from 65 kOe for x = 0.0 (ZnCr2Se4 matrix) up to 42.2 kOe for x = 0.12, above which the spin helical system changed to ferromagnetic (FM). The Hc2 reduction can lead to strong competition among AFM and FM interactions and spin frustration, as the specific heat under magnetic fields H < Hc2 shows a strong field decrease in TN.

This paper reports on the electrical and broadband dielectric spectroscopy studies of Zn2&minus, xMgxInV3O11 materials (where x = 0.0, 0.4, 1.0, 1.6, 2.0) synthesized using a solid-state reaction method. These studies showed n-type semiconducting properties with activation energies of 0.147&ndash, 0.52 eV in the temperature range of 250&ndash, 400 K, symmetric and linear I&ndash, V characteristics, both at 300 and 400 K, with a stronger carrier emission for the matrix and much less for the remaining samples, as well as the dipole relaxation, which was the slowest for the sample with x = 0.0 (matrix) and was faster for Mg-doped samples with x &gt, 0.0. The faster the dipole relaxation, the greater the accumulation of electric charge. These effects were analyzed within a framework of the DC conductivity and the Cole&ndash, Cole fit function, including the solid-state density and porosity of the sample. The resistivity vs. temperature dependence was well fitted using the parallel resistor model. Our ab initio calculations also show that the bandgap increased with the Mg content.

The results of magnetic and dielectric measurements of Zn2􀀀xMgxInV3O11 phases with x = 0:0, 0.4, and 1.6 showed diamagnetic behavior above room temperature and a strong increase in the relative electrical permittivity, "r, with an increase in the magnesium content as well as the high loss tangent, tan , above 150 K, irrespective of the magnesium content in the sample. With the increase in the frequency of the electric field both "r and tan strongly decreased. At low temperatures a residual paramagnetism coming from the paramagnetic ions of vanadium was observed. These effects were interpreted within a framework of the vacancy trapping centers acting as the accumulation of electric charges on the one hand and a mixed valence of vanadium ions on the other.

The manganese doped calcium molybdato-tungstates with the formula of Ca 1- x Mn x (MoO 4 ) 0.50 (WO 4 ) 0.50 ( x = 0.01, 0.03, 0.05, 0.10, 0.125, and 0.15) were successfully obtained by two-step synthesis using in both steps a solid state reaction route. All ceramics show scheelite-type tetragonal structure with space group I4 1 /a . The electrical and magnetic studies within the temperature range of 2–300 K showed a weak p -type electrical conductivity and the paramagnetic state of Mn-doped ceramic materials. With increasing Mn content in samples under study, a change in the short-range interactions from ferromagnetic to antiferromagnetic as well as an increase in the orbital contribution to the magnetic moment, resulting in a strong spin-orbit coupling, were observed. The Brillouin procedure was used to estimate the Lande factor.

The unusual physical characteristics of the multicomponent oxide systems renewed the interest as the potential cathode materials in high-energy cells. Since the earlier magnetic characteristics were not entirely conclusive, we report the results of dc magnetic measurements including higher harmonics of ac magnetic susceptibility of the M 2 FeV 3 O 11 (M = Mg, Zn, Pb, Co, Ni) compounds. Ferrimagnetic long-range and antiferromagnetic short-range interactions for all compounds under study at low temperatures as well as superparamagnetic-like behavior with the blocking temperature of 29 K and the freezing parameter of 0.013 were observed. These effects are discussed within the framework of superexchange and double exchange magnetic interactions as well as the mixed valence band of iron ions.

A series of Co2+-doped and Gd3+-co-doped calcium molybdato-tungstates, i.e., Ca1−3x−yCoy▯xGd2x(MoO4)1−3x(WO4)3x (CCGMWO), where 0 &lt, x ≤ 0.2, y = 0.02 and ▯ represents vacancy, were successfully synthesized by high-temperature solid-state reaction method. XRD studies and diffuse reflectance UV–vis spectral analysis confirmed the formation of single, tetragonal scheelite-type phases with space group I41/a and a direct optical band gap above 3.5 eV. Magnetic and electrical measurements showed insulating behavior with n-type residual electrical conductivity, an almost perfect paramagnetic state with weak short-range ferromagnetic interactions, as well as an increase of spin contribution to the magnetic moment and an increase in the power factor with increasing gadolinium ions in the sample. Broadband dielectric spectroscopy measurements and dielectric analysis in the frequency representation showed a relatively high value of dielectric permittivity at low frequencies, characteristic of a space charge polarization and small values of both permittivity and loss tangent at higher frequencies.

Chalcogenide bulk spinels with general formula CuCr2X4 (X = S, Se, and Te) are ferromagnetic and p-type metallic materials with the thermoelectric figure of merit of 0.15. They can be used to dope or alloy with related semiconducting spinels. Therefore, it is expected that their nanosized crystallites display also unique properties and new potential applications. This paper presents the results of dc and ac magnetic measurements, including the higher harmonics of ac magnetic susceptibility as well as electrical conductivity and thermoelectric power of the CuCr2S4 nanospinels. These studies showed that decreasing the size of crystallites to nanometer scale leads to a dramatic change in their physical properties.

Chalcogenide spinels show a variety of physical properties and are very good candidates for electronic and high-frequency applications. We report the measurements of magnetic susceptibility, magnetic isotherm, electrical conductivity, thermoelectric power and calculations of the superexchange and double-exchange integrals made for singlecrystalline Cu[CrxHfy]Se4 spinels. The results showed a ferromagnetic order of magnetic moments below the Curie temperatures of 390 K and, an increase in the splitting of the zero-field cooled and field cooled susceptibilities with increasing Hf-content below the room temperature suggesting a slight spin-frustration and a rapid transition from semiconducting to metallic state at room temperature. A quantitative evaluation of the exchange Hamiltonian showed that the total hopping integral rapidly decreased and the bandwidth of the 3d t2g band due to Cr3+ and Cr4+ ions strongly narrowed from 0.76 eV for y = 0 to 0.28 eV for y = 0.14. The narrowing of this band appears to be responsible for semiconducting properties of the Hf-doped CuCr2Se4 spinels below the room temperature.

Multicomponent oxide systems have been widely studied in the last few decades and can be used as cathode materials in high-energy cells. However, the electrical characteristics have not yet been fully disclosed. We report the electrical conductivity, thermoelectric power, the I - V characteristics, conductance and dielectric spectroscopy measurements made for M 2 FeV 3 O 11 (M=Mg, Zn, Pb, Co, Ni) ceramics. This multicomponent oxide system was found to show semiconducting properties strongly thermally activated above room temperature, n -type conduction at higher temperatures, higher conductance for the ceramics containing Co 2+ , Ni 2+ and Mg 2+ ions as well as a strong dependence of relative dielectric constant and loss tangent on temperature and frequency. Moreover, the transition metal ions, which have unfilled 3 d -shells strongly affected polarization and conductivity of the ceramics, while the effect of porosity could be neglected. These effects are discussed in terms of microstructure, thermal activation of charge carriers, small polarons as well as the Maxwell–Wagner polarization.

Cu 2 In 3 VO 9 has been characterized by UV–vis–NIR and dielectric spectroscopy and measurements of its electrical conductivity and thermoelectric power to be a semiconductor with the activation energy E a1 =0.61 eV and E a2 =0.03 eV in the intrinsic and extrinsic region, respectively, the direct allowed energy gap E g =1.09 eV, the change of sign of the thermoelectric power from p to n at T n-p =400 K, the strongly temperature-dependent and frequency both dielectric constant ( e r ) and loss tangent (tan δ ) above 160 K. Moreover, the I - V characteristics and conductance provided the evidence of symmetrical and non-linear behaviour typical of strong emission of charge carriers induced by temperature and voltage. These results are interpreted in the framework of vacancy acceptor and donor levels in the honeycomb lattice structure forming a two-dimensional frustrated system assuming the relaxation process like with Maxwell-Wagner or Jonscher.

Microcrystalline samples of new Cd1–3xDy2x⌷xMoO4 solid solution with limited homogeneity (0 3 eV at room temperature and the thermally activated conduction of the Arrhenius-type above 350 K. Moreover, the I-V characteristics provided the evidence of symmetrical and non-linear behavior typical of charge carrier emission weakly induced by the temperature. Relative dielectric permittivity er below 10 as well as loss tangent tanδ below 0.15 do not substantially depend both on the temperature in the range of 76–400 K and the frequency in the range of 5·102–1·106 Hz. These results are interpreted in the framework of the acceptor and donor vacancy centers.

Structural, electrical, magnetic, and specific heat measurements were carried out on ZnCr2Se4 single crystal and on nanocrystals obtained from the milling of this single crystal after 1, 3, and 5 h, whose crystallite sizes were 25.2, 2.5, and 2 nm, respectively. For this purpose, the high-energy ball-milling method was used. The above studies showed that all samples have a spinel structure, and are p-type semiconductors with less milling time and n-type with a higher one. In turn, the decrease in crystallite size caused a change in the magnetic order, from antiferromagnetic for bulk material and nanocrystals after 1 and 3 h of milling to spin-glass with the freezing temperature Tf = 20 K for the sample after 5 h of milling. The spin-glass behavior for this sample was derived from a broad peak of dc magnetic susceptibility, a splitting of the zero-field-cooling and field-cooling susceptibilities, and from the shift of Tf towards the higher frequency of the ac susceptibility curves. A spectacular result for this sample is also the lack of a peak on the specific heat curve, suggesting a disappearance of the structural transition that is observed for the bulk single crystal.

Scheelite-type Ca1−xMnxMoO4 (x = 0.0, 0.01, 0.05, 0.10 and 0.15) nanomaterials were successfully synthesized via a combustion route. Dielectric studies showed a weak n-type electrical conductivity characteristic for insulators and low relative permittivity (er

The results of magnetic and electrical measurements of ZnCr2S4 – nanoparticles (NPs) synthesized by mechanical alloying method showed an almost ideal paramagnetic state with the weak ferromagnetic short-range interactions derived from a small positive paramagnetic Curie-Weiss temperature of θ = 0.9 K and the presence of magnetic NPs confirmed by the significantly lower value of the effective magnetic moment (μeff = 2.089 μB/f.u.) compared to the μeff = 5.215 μB/f.u. for bulk spinel as well as n-type semiconducting behavior with an extrinsic region not thermally activated and with an intrinsic region with an activation energy of 0.253 eV. Broadband dielectric spectroscopy measurements showed the relaxation processes only in the intrinsic region of the electrical conductivity, i.e. above 170 K, in which the dipole relaxation becomes faster as temperature rise. These results are interpreted in the framework of the Cole-Cole function and a hopping variable range model including structural defects.

ZnCr2Se4 spinel single crystals doped with neodymium ions having concentrations of 0.05, 0.08 and 0.10 and occupying tetrahedral positions were synthesized using chemical vapour transport. Thermal analysis as well as electrical conductivity, magnetic isotherm, and magnetic susceptibility measurements showed thermal stability at higher temperatures, semiconducting behavior with a metal-insulator transition at TMI ≥ 330 ​K, an antiferromagnetic order with a Neel temperature TN ​= ​21.5 ​K, a short-range ferromagnetic interactions evidenced by a positive Curie-Weiss temperature θ ​= ​55, 60 and 68 ​K with increasing Nd-content in the sequence 0.05, 0.08 and 0.10, two critical fields Hc1 and Hc2 at 10 and 60 ​kOe, regardless of the Nd-content. The specific heat studies showed more complex magnetic transitions, i.e. two magnetic transitions at TN and at spin-glass temperature (TSG) for the Nd-poorer samples and only one magnetic transition at TN for Nd-richer ones. These effects are interpreted in terms of the superexchange integrals for the first two coordination spheres including chemical bond length and spin fluctuation.

Single crystal of new cadmium and neodymium molybdate solid solution (Cd 0.958 Nd 0.028 □ 0.014 MoO 4 , where □ denotes cationic vacancies) has been successfully grown by the Czochralski method. The X-ray diffraction analysis confirmed that this solid solution crystallizes in the scheelite type structure, the Nd 3+ ions do not show long-range order and they are randomly distributed in the unit cell, substituting the Cd 2+ ions. As a consequence, the unexpected properties of CdMoO 4 :Nd 3+ are observed such as the energy gap (~1.77 eV) twice smaller than that of the matrix CdMoO 4 , a paramagnetic state with the short-range ferromagnetic interactions, behavior related to the electrical conductor with p – n transition along the 〈100〉 axis, the semiconducting behavior with n – p transition along the 〈001〉 axis and the diode-like behavior found to be of Schottky- or Maxwell-Wagner type. Therefore, we predict great potential of this single crystal for technical applications in electronic devices.

UV–vis–NIR and electrical investigation of AgY 1− x (Gd,Nd) x (WO 4 ) 2 and MRE 2 W 2 O 10 (M=Cd, Co, Mn; RE=Y, Nd, Sm–Er) tungstates as well as Cd 1−3 x Gd 2 x □ x MoO 4 molybdates proved them to be in the insulating state. The calculated value of the direct allowed energy gap E g >2.4 eV. Only for CoPr 2 W 2 O 10 , MnPr 2 W 2 O 10 and Cd 1−3 x Gd 2 x □ x MoO 4 solid solutions when 0.0238≤ x ≤0.0839, thermally activated conduction of the Arrhenius-type was observed. The I–V measurements at higher temperatures showed lower carrier emission for AgY 1− x (Gd,Nd) x (WO 4 ) 2 solid solutions and higher ones for the remaining samples. Colossal increase in electron emission of MPr 2 W 2 O 10 (M=Co, Mn) and in Cd 1−3 x Gd 2 x □ x MoO 4 for 0.0098 ≤ x ≤0.0839 at 400 K is interpreted in the framework of the Poole–Frenkel effect and a small polaron mechanism, respectively.

The UV–vis–NIR and electrical conductivity σ ( T ) measurements of RE 2 W 2 O 9 (RE = Pr, Sm–Gd) showed the insulating state and the calculated value of the direct allowed energy gap E g > 3.5 eV. Thermoelectric power S ( T ) measurements showed the n-type conduction for Sm 2 W 2 O 9 and Eu 2 W 2 O 9 as well as p-type one for Pr 2 W 2 O 9 and for Gd 2 W 2 O 9 . The I – V characteristics, measured at 300 and 400 K, showed the symmetrical and linear behaviour of electron emission, slightly higher at higher temperature. Relative dielectric permittivity ɛ r as well as loss tangent (tan δ ) do not depend both on the temperature in the range of 76–400 K and the frequency in the range of 5 × 10 2 –1 × 10 6 Hz. ɛ r increases from 8 via 11 and 18 to 33 in the sequence: Gd, Eu, Pr and Sm, respectively. Since the loss factor is close to zero (tan δ

The CuCr2S4 nanoparticles obtained by high-energy ball milling of CuS and Cr2S3 sulphides were about 3.3 nm in size. SEM images showed formation of smaller or larger agglomerates and DFT based ab-initio calculations exhibited metallic ground state with band gap of 0.8 eV width just above (~0.5 eV) the Fermi level and magnetic moments located mostly at Cr sites. Measurements of magnetic susceptibility, magnetic hysteresis, electrical conductivity and thermoelectric power showed antiferromagnetic order with the Neel temperature of 40 K, superparamagnetic-like behaviour with the blocking temperature of 90 K, n-type conductivity, and a metal-insulator transition at 375 K and below this temperature the variable-range hopping in the temperature range of 108 K

Polycrystalline samples of new scheelite-type tungstates, Pb1−3x xPr2xWO4 with 0.0098 ⩽ x ⩽ 0.20, where denotes cationic vacancies have been successfully prepared by a high-temperature solid-state reaction method using Pr2(WO4)3 and PbWO4 as the starting reactants. The influence of the Pr3+ substitution in the scheelite framework on the structure and optical properties of prepared new ceramic materials has been examined using powder X-ray diffraction method (XRD) and UV-Vis-NIR spectroscopy. The results of dielectric studies of Pb1−3x xPr2xWO4 samples showed both low values of dielectric constant (below 14) and loss tangent (below 0.2). The electrical conductivity and thermoelectric power measurements revealed a low conductivity (∼2 × 10−9 S/m) and the sign change of thermoelectric power around the temperature of 366 K suggesting the p-n transition. These results are discussed in the context of vacancy, acceptor and donor levels as well as the Maxwell-Wagner model.

Polycrystalline samples of α-AgY1−xGdx(WO4)2 with x=0, 0.005, 0.01, 0.025, 0.05, 0.1, 0.2, and 1 have been prepared by a solid state reaction method and the influence of Gd3+ substitution for Y3+ on microstructure, thermal and magnetic properties was investigated. The X-ray diffraction analysis showed the phases to crystallize in the monoclinic symmetry, space group C2/m. A reversible monoclinic to tetragonal phase transition occurs in AgY1−xGdx(WO4)2 and strongly depends on Gd3+ ion concentration. Electron paramagnetic resonance (EPR) spectra of Gd3+ ions showed non-monotonous dependence of interaction strength on gadolinium concentration. Magnetic measurements showed paramagnetic behavior and strong increase of magnetic moment as the yttrium content decreases.

The electrical conductivity (T) and thermoelectric power S(T) measurements of Sr2InV3O11 showed the insulating state and the change of sign of thermopower from p to n at Tn􀀀p = 400 K. The I–V characteristics provided the evidence of symmetrical and non-linear behaviour typical of strong emission of charge carriers induced by temperature and voltage. Relative dielectric permittivity "r as well as loss tangent (tan ) strongly depend both on the temperature in the range of 295–400 K and the frequency in the range of 5 102 to 1 106 Hz, showing the broad maximum at 320 K. These effects are considered as a relaxation process like in the Maxwell–Wagner or Jonscher model as well as the conduction of electric current, as determined by the Joule–Lenz law[…]

The UV-vis-NIR and electrical properties of Yb8􀀀xYxV2O17 for x = 0, 2, and 8 were investigated. The band energy gap of 2.6 eV determined for Yb6Y2V2O17 (x = 2) and comparable for the remaining compounds with x = 0 and 8 is characteristic for insulators. Low electrical conductivity with a characteristic minimum shifting to higher temperatures from 322, via 360 to 370 K in the sequence x = 0, 2 and 8, which decreases with increasing content of ytterbium was observed. Temperature dependence of thermoelectric power showed n􀀀p transition at 410 and 467 K for x = 0 and 2, respectively, and n-type conductivity for x = 8, indicating mainly n-type electrical conductivity. A breakdown voltage of 26 V/mm is mainly observed for the I􀀀V characteristics at 400 K and showing a varistor-like behawior[…]

Polycrystalline samples of new copper and samarium tungstates (Cu 3 Sm 2 W 4 O 18 and CuSm 2 W 2 O 10 ) and cobalt and europium tungstate (CoEu 4 W 3 O 16 ) have been successfully synthesized by the solid state reaction of d -electron metal tungstates MWO 4 (M = Cu, Co) with corresponding rare-earth metal tungstate RE 2 WO 6 (RE = Sm and Eu). Broadband dielectric spectroscopy provides experimental evidence that in tungstates under study both relative dielectric permittivity ( ɛ r ) and loss tangent (tan δ ) strongly depend on the temperature and frequencies. Maximal relative permittivity value ɛ r = 42 for CuSm 2 W 2 O 10 , ɛ r = 30 for Cu 3 Sm 2 W 4 O 18 , and ɛ r = 63,000 for CoEu 4 W 3 O 16 at low frequency ( ν = 0.1 Hz) and at 373 K indicates that only these ions which have the large number of unpaired and unscreened electrons on the unfilled shells are responsible for the colossal dielectric effect.

We performed all atoms molecular dynamics simulations of ethylene glycol embedded inside single walled (17,0) and (10,10) carbon nanotubes, as well as bulk ethylene glycol, to study the influence of the spatial constraints and interaction between the embedded molecules and internal surface of the nanotubes on thermal activation of the system and deviation from purely Debye relaxation characteristic observed in bulk ethylene glycol liquid.

Resume Objectif Il a ete mis en evidence dans la litterature des effets irritatifs, allergiques, toxiques cancerogenes mais aussi mutagenes et reprotoxiques lors d’expositions professionnelles aux produits cytotoxiques. En 2008, des preparateurs de chimiotherapies anticancereuses du CHRU de Brest ont exprime des craintes pour leur sante lors des visites periodiques de medecine de sante au travail. Un groupe de travail a ainsi ete cree et un questionnaire a ete elabore pour les differentes categories professionnelles de l’institut de cancerologie-hematologie afin d’analyser les risques potentiels d’exposition aux cytostatiques, faire un point sur les moyens de protection et la formation. Deux ans apres la mise en place des nouvelles procedures de protection, nous avons souhaite faire un bilan sur l’utilisation des equipements de protection individuelle (EPI), la formation, la connaissance de ces procedures et des conduites a tenir en cas d’accident. Methode Dans cette optique, un questionnaire a ete mis en place et adresse aux differents agents de l’institut de cancerologie-hematologie au courant du premier trimestre 2012. Resultats et conclusion Il en ressort une amelioration des connaissances en matiere d’EPI ; nous avons pu constater que la plupart des personnes interrogees etaient au courant des conduites a tenir en cas d’accident meme s’il demeure des interrogations au sein des differentes categories professionnelles et que des progres doivent encore etre faits dans ce domaine notamment en matiere de formation, sensibilisation du personnel et conduite a tenir pour les femmes enceintes.

The values of the direct allowed energy gap determined from the UV-vis-NIR measurements and Kubelka– Munk transformation decrease from 3.38 via 2.70 to 2.42 eV for MPr2W2O10 in the sequence M = Cd, Co, Mn, while the values of the activation energy increase from 0.11 via 0.44 to 0.47 eV in the same sequence. In other words, the higher the activation energy, the smaller the energy gap. Because the energy gap is typical for insulators, so electron transport phenomena are considered under the Poole–Frenkel effect and small-polaron mechanism.

Resume Objectif L’evaluation des risques chimiques professionnels en etablissement de sante est complexe et doit repondre a de nombreuses obligations reglementaires. L’objectif de ce travail est de valider des guides et methodes d’aide a l’evaluation des risques chimiques qui soient adaptes aux specificites des etablissements de sante. Methode Au sein du reseau national hospitalo-universitaire de medecine du travail, la methode d’evaluation des risques chimiques developpee est validee par son application simultanee dans les laboratoires d’hematologie de cinq CHU. Un logiciel d’aide a l’evaluation des risques est egalement teste et utilise comme outil d’echanges de donnees entre etablissements. Resultats La methode d’evaluation, basee sur la hierarchisation des risques chimiques par types d’effet et voies d’entree dans l’organisme, est validee dans le secteur des laboratoires. L’etude menee en laboratoires d’hematologie permet la caracterisation des produits dangereux et des situations de travail a risque, lesquelles sont relativement limitees eu egard aux faibles quantites manipulees et a l’automatisation de nombreuses analyses. Les principaux produits dangereux identifies font l’objet de l’edition de fiches de toxicite incluant les principales informations cliniques, techniques et reglementaires importantes pour les utilisateurs. Le logiciel valide permet la saisie de la toxicite des substances, la tracabilite des expositions professionnelles et l’edition automatisee de rapports d’evaluation. Un module de formation aux risques chimiques est cree afin de pallier le manque de connaissances sur ce risque constate au cours de l’etude. Conclusion Les differents outils crees doivent permettre de faciliter les demarches locales d’evaluation des risques chimiques en etablissements de sante. Les echanges sur ce theme dans le cadre de reseaux interetablissements apparaissent primordiaux afin de mutualiser les competences et les informations en la matiere.

Results of studies on variations of the critical temperature ( T C ) due to the action of high hydrostatic pressure ( p ) are presented. Studies were conducted in three series of critical solutions composed of a dipole component (nitrobenzene, o-nitroluene, 1-nitropropane) and a non-dipole solvent ( n -alkanes). For solutions containing nitrobenzene and o-nitrotoluene the sign and value of d T C /d p depend on the length of the molecule of n -alkane. Additional studies on dipole-dipole interactions between molecules of the dipole components by means of the nonlinear dielectric effect indicate their important influence on d T C /d p .

In uence of Cr-Substitution on the Electrical Properties of Fe1−xCrxVSbO6 H. Duda, E. Filipek, G. Dibrowska, T. Gro« and T. Mydlarz University of Silesia, Institute of Physics, Uniwersytecka 4, 40-007 Katowice, Poland West Pomeranian University of Technology, Szczecin, Department of Inorganic and Analytical Chemistry al. Piastow 42, 71-065 Szczecin, Poland International Laboratory of High Magnetic Fields and Low Temperatures, Gajowicka 95, 53-529 Wrocaaw, Poland

The aim of this study was an evaluation of the activity of parafollicular (C) cells in a rat experimental model of hyperthyroidism, evoked by an intraperitoneal application of L-thyroxine (40 mg/kg daily) over 15 days. For that reason, immunohistochemical investigations and evaluation of calcitonin (CT) plasma concentrations were performed. Differences in the quantity and distribution, together with enhanced CT-immunoreactivity of C cells, were observed in hyperthyroid rats, in comparison to respective values in the control group, accompanied by a significant diminution of plasma TSH and CT levels. Our preliminary study may point to a functional interaction between follicular and parafollicular cells in the thyroid gland.

The aim of this study was to evaluate the influence of co-exposure to cadmium (Cd) and ethanol on the structure and function of the thyroid. Male Wistar rats were exposed to 50 mg of Cd/dm3 in drinking water and ethanol in a dose of 5 g/kg body wt/24 h (administered intragastrically in two equal doses for 5 days a week) for 12 weeks. The structure of the thyroid was assessed in a light microscope. Immunohistochemical methods were used to determine calcitonin (CT), the calcitonin-gene related peptide (CGRP), somatostatin (ST) and synaptophysin (SPh) in the thyroid parafollicular cells (C cells). Weakening of the reactions for CT, CGRP, ST, SPh was observed in C cells. The animals, exposed to a combined action of Cd and ethanol, showed signs of enhanced activity (elevated light follicular epithelium and rarefied colloid), as well as features of intensified remodelling (partial or total follicular atrophy and the appearance of new follicles) of the thyroid gland. In some fragments of the connective tissue stroma mononuclear cell infiltration was observed. The nature of the changes, observed in the rats, simultaneously exposed to Cd and ethanol, may suggest an enhancement in the function of C cells.

In patients with chronic renal failure, mechanical and haemodynamic changes could occur in the lungs without obvious pulmonary symptoms and findings, and their effects could pave the way to pulmonary functional disorders. Numerous studies have demonstrated that the respiratory system is a site of synthesis of many compounds, which play biological roles ascribed to hormones. The present article is an attempt to make a synthesis of current opinions and views, based on the world literature survey and on our own studies, concerning the effect of homeostatic dysfunction of the kidneys on the morphology and action of DNES cells in the lung.

The aim of the study was an evaluation of the activity of mast cells and mark activity tryptase and chymase and of protein levels in experimental fibrosarcoma, induced in rat skin. The experiments were carried out on 50 male Wistar rats. The cancer was induced in rats by one subcutaneous injection of 0.2 mg 3-methylcholanthrene in 0.25 ml of olive oil. Tissue material was fixed in Bouin's fluid. Immunohistochemical tryptase detecting reactions were performed--using specific antibodies and the ABC complex. The activities of tryptase and chymase and protein levels were determined in supernatant of 10% homogenate. We found a very significant growth of mast cell quantity in the connective tissue of tumours. We observed slight differences in the activity of examined enzymes in tumours of different mass.

In our experiment, we tried to assess the potential of repair of full-thickness defects in articular cartilages of rabbit femurs. An artificially made, full-thickness defect in the rabbit's femoral patellar groove was created. The defects were divided into six groups. The reparative tissue was evaluated by macroscopic, histological, and immunohistochemical examinations. The reparative tissues in defects with transplanted chondrocytes, had mostly a hyaline-like cartilage appearance and were firmly attached to the surrounding normal cartilage. Only in the control group with periosteal flap and broken subchondral plate, there were signs of partial repair. Self repair of rabbit articular cartilage is very limited. Transplantation of chondrocytes, costal and articular, without differences between groups, is a very potential treatment, producing hyaline-like repair tissue with good histological results.

The aim of this study was to compare what changes are caused by high doses of cholecalciferol (100,000 UI vD3) and CaCl2 on thyroid parafollicular (C) cells and airways neuroendocrine (NE) cells in rat. Overdosage of vD3 and CaCl2 causes hypocalcaemia and strong hypercalcitoninemia in blood; C cells showed mainly signs of hypertrophy; simultaneously, the number of strong calcitoninpositive cells decreased significantly (statistically significant changes). Immunohistochemical reactions, detecting CGRP, somatostatin, synaptophysin and neuronspecific enolase did not fall under statistic analysis. Airways NE cells re-acted to hypercalcemia differently than C cells--they probably respond to different regulatory mechanisms.

The aim of the study was the evaluation of angiogenesis processes in fibrosarcoma induced by 3-methylcholanthrene (3-Mc) in reference to the number of mast cells (MCs). 76 male Wistar rats were divided into 4 groups: two experimental (E) groups--after injection of 0.2 mg 3-Mc dissolved in olive oil (0.25ml), and 2 control (C) groups. In E1 group, 52 rats were killed after development of the fibrosarcoma; E(2)--10 rats were killed before development of the tumor; C(1)-8 rats received 0.25ml olive oil; C(2)--8 rats received no treatment. Tissue material was fixed in buffered formalin or Carnoy's and Bouin's fluid. Paraffin sections were stained with H+E and Azan methods, and with alcian blue-saphranine and toluidine blue. Immunohistochemical reactions detecting tryptase in MCs were also performed. Angiogenic objects (microvessels and single endothelial cells) were recognized using antibodies against factor VIII (vWF), P selectin (CD-62P), and CD-90. We found a distinct relationship between intensification of neoangiogenesis at the tumor periphery and increased number of MCs.

The effect of chronic (12 months) oral cadmium (Cd) administration (5 or 50 mg Cd/dm3) to rats on the structure and function of the thyroid was evaluated. Paraffin thyroid and parathyroid sections were stained with H+E and immunocytochemically for calcitonin (CT), somatostatin (ST), synaptophysin (SPh), chromogranin A (CgA) and thyroid transcription factor-1 (TTF-1). Serum levels of thyroid hormones: triiodothyronine (T3) and tetraiodothyronine (T4) as well as levels of Cd in the blood and calcium (Ca) in the serum were estimated. CT, ST and SPh were detected in C cells of the thyroid, while CgA in both thyroid and parathyroid cells. In animals exposed to Cd, proliferation of CT- and SPh-positive thyroid C cells was observed, ST being found only in very few C cells--both in control animals and in those exposed to Cd. Serum T3 concentration was not affected by Cd, while T4 was reduced but only at the exposure to the higher Cd concentration. Moreover, the rats exposed to Cd showed a decrease in serum Ca concentration.

Hormonal disorders are the permanent symptoms of renal failure. They concern all known hormones and can be due to quantitative changes of the secretory activity and disturbances of endocrine cell functions. The aim of this study was to establish whether experimental thyroparathyroidectomy in uremic animals causes detectable histomorphological changes in endocrine cells of pancreatic islets. Thyroparathyroidectomy was performed in rats 30 days after nephrectomy. Fragments of pancreatic tissue were collected 14 days after the operation. Paraffin sections were stained with H+E and by silver salt impregnation. Immunohistochemical reactions were conducted using antibodies against calcitoningene-related peptide (CGRP), synaptophysin (SPh), somatostatin (ST), neuron-specific enolase (NSE), and chromogranin (CgA). It was shown that endocrine cells of pancreatic islets in thyroparathyroidectomized rats show intensified immunoreactivity to SPh and ST as compared to the control group of animals. Immunocytochemical reactions for NSE, CgA, and CGRP were negative.