OBJECTIVEThe objective of this study is to investigate the influence of mechanical properties and sintering performance by adding 5% weight percentage aids to nano-compound zirconia toughened alumina (ZTA) ceramics.

METHODSMicrometer Al2O3 and nanometer ZrO2 (quality ratio 4:1) were used to get 55% volume percentage slurry. Magnesium oxide and titanium oxide were taken as aids which were 5% weight percentage of the Al2O3 and ZrO2 powder. Five groups (number 0, 1, 2, 3, 4 group) were divided according to different proportion of aids. After gel-casting, the porcelain pieces were sintered at 1150, 1200, 1300, 1400, 1450, 1500, 1600 degrees C for 2 hours. Static three-point flexure strength, line shrinkage, relative density were measured and scanning electron microscopy (SEM) was used to observe section.

RESULTSNumber 1 (MgO 1%, TiO2 4%) group had the highest bending strength. It was (401.78+/-19.50) MPa after sintering at 1600 degrees C for 2 hours and was higher than 0 group (380.64+/-44.50) MPa. Bending strength became lower than 0 group when MgO was more than 2% or more than that weight percentage of ZTA powder. When MgO content was higher than 2% or more than that weight percentage, there was no difference in relative density raising rate between each sintering assistants groups. When the sintering temperature was higher than 1200 degrees C, all groups showed obvious line-shrinkage and the groups which contained sintering assistants were all was higher than 0 group.

CONCLUSIONAdding MgO and TiO2 aids from 1% to 4% weight percentage of ZTA will promote fritting and increase ZTA nano-compound ceramics mechanical properties. Adding 2% MgO aids or more than that weight percent will has no obvious help to increase the relative density raising rate of ZTA nano-compound ceramics and will degrade the mechanical properties of ZTA nano-compound ceramics.

Aluminum Oxide ; Dental Porcelain ; Microscopy, Electron, Scanning ; Temperature ; Titanium ; Zirconium

OBJECTIVETo study the MRI manifestation of testicular tumor and the value of MRI in the diagnosis of the disease.

METHODSWe retrospectively analyzed 23 cases of pathologically confirmed testicular tumor, and observed the morphological characteristics, signals and surrounding conditions of the tumor using plain and enhanced MRI scanning.

RESULTSOf the 23 cases, seminoma was identified in 7, mixed germinoma in 3, teratoma in 3, endodermal sinus tumor in 2, epidermoid in 1, Leydig cell tumor in 1, leucoma in 1, nonspecific inflammatory mass in 3, and tuberculosis in 2. MRI revealed the precise locations and specific characteristics of

CONCLUSIONBased on MRI findings and clinical manifestation, most testicular tumors can be diagnosed correctly.

Adolescent ; Adult ; Carcinoma, Embryonal ; diagnosis ; Child ; Child, Preschool ; Endodermal Sinus Tumor ; diagnosis ; Germinoma ; Humans ; Infant ; Leydig Cell Tumor ; diagnosis ; Magnetic Resonance Imaging ; Male ; Middle Aged ; Retrospective Studies ; Seminoma ; diagnosis ; Teratoma ; diagnosis ; Testicular Neoplasms ; diagnosis ; Young Adult