High temperature and composition induced phase transitions in LiZnV1-xAsxO4 phenacites: Crystal structure and Raman spectroscopy studies.

In this work, using techniques of X-ray diffraction and Raman spectroscopy, we report the composition and high-temperature induced phase transition in the system LiZnV1-xAsxO4 (0⩽x⩽1). Both techniques showed that the increase of arsenic amount induced a structural transition from R-3 LiZnVO4 type to LiZnAsO4 type belonging to R3 space group, the transition occurring between x=0.7 and x=0.8. Furthermore, increasing temperature for the compositions (0.8⩽x⩽1) manifests a transition from the LiZnAsO4 structural type with R3 space group to the R-3 LiZnVO4 structural type. For this series, the transition from the space group R3 to the centro-symmetric space group R-3 shows considerable changes in the compositional and temperature dependencies of the bands: spectral positions of all the observed Raman bands exhibit shifts linearly proportional to the temperature increase, with points of shift-rate changes revealing a symmetry change. The Raman-spectra based temperature-composition phase diagram confirms the results obtained using the method of Rietveld refinements, thus showing the R-3 to R3 transition occurring between x=0.7 and 0.8.

Vibrational spectra and factor group analysis of M0.50TiOPO4 oxyphosphates (M=Mg, Zn, Ni, Co, Fe and Cu).

Raman spectra of a series of orthophosphates M(0.50)TiO(PO(4)) (M=Mg, Zn, Ni, Co, Fe, and Cu) have been recorded in crystalline state. Factor group analysis has been performed for space group P2(1)/c and assignments of the internal modes of the [PO(4)] tetrahedra and [TiO(6)] octahedra have been made.

[Operative fertiloscopy results. About 67 cases]. / Résultats de la fertiloscopie opératoire. À propos de 67 cas.

OBJECTIVE: To assess the impact of operative fertiloscopy on fertility. PATIENTS AND METHODS: A retrospective study over a period of 3 years of 67 consecutive patients who received operative fertiloscopy and were followed over an 18 months period. RESULTS: The patients average age was 34 years (24-42) with a 3-year average infertility duration (1-15). We obtained 34 pregnancies (50.7%) (spontaneous or after intrauterine insemination) with 27 live births (38.8%). DISCUSSION AND CONCLUSION: The operative fertiloscopy seems to give good results. It is reserved for minimal or moderate endometriotic lesions and adhesions. These results must be confirmed by largest prospective controlled studies.

Calibration of plane parallel ionization chambers: a new service for secondary standard dosimetry laboratories?

This paper presents the results of calibration of PTW Markus and NACP ionization chambers following the procedures outlined in the TRS 381 International Atomic Energy Agency code of practice. According to this dosimetry protocol, calibration of plane parallel chambers follows 2 methods. The first method uses a high-energy electron beam and consists of comparing the plane parallel chamber with a cylindrical chamber whose N(D,air) calibration factor, traceable to cobalt-60 (60Co), is known, while the second method applies to a 60Co gamma beam whose air kerma rate is known at the calibration point. As the second method is generally applied in Secondary Standard Dosimetry Laboratories, the consistency of calibrations free in-air and in a water phantom has been studied. A close agreement is shown between the 2 methods (the calibration factors differ by at most 0.98%). These results lead to the conclusion that either of the 2 calibration methods can be used, provided that the correction factors given by the TRS 381 code of practice are applied.