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Relaxor behaviour and phase transition of perovskite ferroelectrics-type complex oxides(1–x)Na_(0.5)Bi_(0.5)TiO_3–xCaTiO_3 system

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Journal of Advanced Ceramics 2018年第2期7卷 124-142页

作者： Roy ROUKOS nissrine zaiter Denis CHAUMONT Laboratoire Interdisciplinaire Carnot de Bourgogne UMR 6303 CNRS Université de Bourgogne

Polycrystalline powders of (1–x)Na_(0.5)Bi_(0.5)TiO_3–xCaTiO_3 ((1–x)NBT–xCT, 0 ≤ x ≤ 0.55) have been synthesized by solid state route. The effects of simultaneous substitution of Na^+/Bi^(3+) at A-site in NBT on structural and dielectric properties were investigated. X-ray diffraction analysis revealed the phase transition from rhombohedral structure(x = 0) to orthorhombic structure(x ≥0.15). A distinct behaviour in dielectric properties was obtained, where for x = 0, a normal ferroelectric behaviour was observed, whereas for x ≥ 0.15, a broad dielectric anomaly was revealed such that the maximum temperature(T_m) strongly depended on the frequency and shifted towards low temperature with CT. The dielectric dispersion indicated a relaxor behaviour revealed by the degree of diffuseness and modelled via Vogel–Fulcher relation. The study highlighted the relaxor behaviour as a function of frequency and proved the transformation from a relaxor high-frequency dependence to a paraelectric phase at temperature T_s. The distinct variation of the Raman spectra at room temperature was correlated with X-ray diffraction results and proved the already mentioned transition. On heating(-193–500 ℃), the Raman spectra confirmed the structural stability(Pnma) of the materials. The phonon behaviour for x = 0.15 was discussed in terms of the appearance of polar nanoregions(PNRs) into a non-polar orthorhombic matrix responsible of the relaxor behaviour. For x = 0.20, unchanged phonon behaviour confirmed the variation in dielectric behaviour where the solids transformed from a relaxor to a paraelectric state without structural phase transition.

关键词： relaxor behaviour dielectric properties Vogel–Fulcher relationship polar nanoregions (PNRs) X-ray diffraction Raman spectroscopy

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Epidemiology and Outcome of Primary Cerebral Lymphoma in Immunocompetent Patients: A Monocentric Study

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Open Journal of Modern Neurosurgery 2022年第3期12卷 141-152页

作者： Fatima Ezzahra Rida Asmaa Harrach Mouna Lamchahab Mohammed Rachid nissrine Khoubila Siham Cherkaoui Abdellah Madani Meryem Qachouh Department of Hematology and Pediatric Oncology Ibn Rochd University Hospital Center Casablanca Morocco Faculty of Medecine Hassan II University Casablanca Morocco

Primary cerebral lymphoma (PCL) is a form of extranodal non-Hodgkin’s lymphoma with a poor prognosis. Very few cohorts have been reported in the literature. It is a rare form in 1% of extranodal lymphomas, and 3% to 4% of brain tumors. The most common histological type is diffuse large B-cell lymphoma. Survival is improved by combining immunotherapy with chemotherapy. This is a descriptive retrospective study conducted at the Casablanca hematology center over a period of 9 years. The aim of this study was to report our experience by studying the clinical, paraclinical, therapeutic and evolutionary profile of patients with primary cerebral lymphoma. We present a study of 22 patients with PCL. The clinical, radiological and histological findings are shown along with the results of treatment. Patients were aged 25 - 75 years (mean 47 years) with a male predominance (77%). Computed tomography (CT) scans were performed on 16 patients (73%) and Brain magnetic resonance imaging for 16 patients (73%). Typically, lesions were multiple, isodense, and showed uniform enhancement with contrast medium. Immunocytochemical studies demonstrated 21 B-cell and 1 mantle-cell lymphomas. All patients received chemotherapy through high-dose MTX with whole brain radiotherapy (WBRT). After a median follow-up of 19 months, 54% are in complete remission, 32% have died, and 14% are lost to follow-up. Overall survival at 24 months and 36 months were 72% and 52%. The event-free survival at 24 months and 36 months were 60% and 48%. This study was to investigate the clinical features of PCNSL, and evaluate the efficacy of high-dose methotrexate (MTX)-based chemotherapy for immunocompetent Moroccan patients with PCNSL.

关键词： Primary Cerebral Lymphoma (PCL) Retrospective Study Management

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Ovarian desmoplastic small round cell tumors: Prognosis is poor! Case report

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Open Journal of Obstetrics and Gynecology 2013年第2期3卷 235-238页

作者： Hanane Saadi Hind Fatmi nissrine Mamouni Sanaa Errarhay Chahrazed Bouchikhi Afaf Amarti Abdelaziz Banani Department of Gynecology Obstetrics I University Hospital Hassan II Fez Morocco Department of Pathology University Hospital Hassan II Fez Morocco

The tumor desmoplastic small round cell in women is rare. Ovarian its location is exceptional. We report a patient of 20 years, the originalNorth Africawho consulted for an increase in abdominal volume with impaired general condition. Pelvic ultrasonography and computed tomography were in favor of multiple peritoneal masses with ascites. After surgical exploration, the histological and immunohistochemical data for diagnosis small round cell desmoplastic tumor of ovarian the patient was a candidate for poly chemotherapy but she was died a month later. Diagnosis relies on histological and immunohistochemical data. The demonstration of a nonrandom translocation t (11;22) (p13;q12) is specific for the disease. The management is multidisciplinary and combining surgery, a poly aggressive chemotherapy and radiotherapy. The prognosis remains poor.

关键词： Small Round Cell Desmoplastic Tumor Ovarian Diagnosis Treatment Prognosis

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