PACS 75.50. Pp, 75.60.Ej We studied the structural and magnetic properties of Ti 1-x Co x O 2 powder samples synthesized by the solgel method. In order to study the post annealing effect on the magnetic properties, the same precursor was annealed at 770 K for 5 h in air and in the pressure of 10 -6 Torr. In the case of samples annealed in vacuum, enhanced ferromagnetism was observed at room temperature, while only paramagnetic behavior was observed in samples annealed in air. Moreover, the magnetization of the vacuum-annealed sample sharply decreased around 650 K while measuring in air, but such decrease in the magnetization was almost absent while measuring in He gas up to 750 K. The structural studies showed dominant anatase and minor rutile phases in vacuum-annealed samples, while an additional nonmagnetic CoTiO 3 phase was observed in airannealed samples. We attribute the enhanced magnetization in the vacuum-annealed sample to the oxygen deficiency which prevents the formation of non-magnetic CoTiO 3 complexes. It is also possible that the reduced oxygen environment can promote the clustering of Co-rich clusters as evidenced by transmission electron microscopy in samples of x = 0.1, thus giving rise to an enhanced ferromagnetic behaviour. However, no direct observation of Co clusters in samples for x ≤ 0.05 was made. [4]. Oxide semiconductors are transparent for visible and near-infrared regions, and can be doped heavily with n-type carriers. Among them, Co-doped TiO 2 anatase is ferromagnetic well above the room temperature [2,5]. Several subsequent reports agree with the results [6 -9], while the other studies report that the precipitation of Co metal cluster is the origin of ferromagnetism [10][11][12]. While the mechanism of ferromagnetism has not yet been definitively elucidated, this unusual contradicting result has prompted many speculations that the growth conditions of the samples and/or the subsequent annealing conditions can be one of the important factors that determine the magnetic state of Co [9,13]. In this work, we studied the post annealing effect on the magnetic properties of Ti 1-x Co x O 2 powder prepared by sol-gel method and found the oxygen plays a crucial role not only on the structural properties but also on the magnetic properties of the samples.
Abstract. Congenital nephrogenic diabetes insipidus (Cndi) is a rare inherited disease, characterized by an inability of the kidney to concentrate urine in response to vasopressin. Three different inheritance patterns have been described, i.e., the X-linked recessive form associated with arginine vasopressin V2 receptor (AVPR2) gene mutations, the autosomal recessive and dominant forms of Cndi associated with mutations in the aquaporin-2 (AQP2) gene encoding the vasopressinregulated water channel of the renal collecting duct. our case is an 18-year-old male patient who complained of severe polyuria since his infancy. But his developmental and growth status were normal. He was diagnosed as Cndi by water deprivation test and genomic dna sequencing, which revealed high plasma aVP levels but persistently low urine osmolalities to 6 h-water deprivation and the novel missense mutation S216F in exon4 of the AQP2 gene. immunohistochemistry of renal biopsied tissue revealed that most of the aQP2 labeling was seen intracellularly in a dotted pattern in the collecting duct principal cells. Immunoblotting of urine samples revealed significantly decreased urinary excretion of AQP2 (~7% of normal control). Here, we report a new case of Cndi associated with the novel missense mutation of the AQP2 gene.
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