Dental implant outcomes in postmenopausal women undergoing hormone replacement

To determine if hormone supplementation reduces the risk of failure for osseointegration of dental implants in postmenopausal women, the treatment outcomes of 116 women older than age 50, treated with 450 endosseous dental implants, were analyzed in this retrospective study. The findings indicated that hormone replacement therapy may not be linked with improved outcomes of endosseous dental implant treatment in postmenopausal women. Smoking, however, appears to significantly increase the implant failure rate in the group observed in this study.     

多晶La_(0.49)Sr_(0.51)(Mn_(1-x)Nb_x)O_3的电输运特性研究

测量了B位掺杂的钙钛矿结构锰氧化物La0 49Sr0 51(Mn1-xNbx)O3(x=0,0 05,0 15和0 25)的电阻率和磁化强度的温度特性.实验结果表明,当Nb5 部分替代B位的Mn4 离子时,电阻率-温度特性由原来单一的半导体型转变成了高温时的半导体(绝缘体)型和低温时的类金属型.随Nb掺杂量增大,电阻率迅速升高3～5个数量级,半导体(绝缘体)-类金属转变温度降低.在掺杂Nb的样品中,只观察到顺磁-铁磁转变,而未观察到铁磁-反铁磁转变.上述实验结果的一种可能解释是掺杂改变了磁有序时电子自旋的排列和空间取向,从而改变载流子被自旋热涨落的散射作用和载流子转移的随机性.     

Stability Kernel of the Quadratic Vector Problem of Boolean Programming

A vector problem of Boolean programming with quadratic partial criteria is investigated. A set of Pareto-optimal solutions (efficient solutions) that preserve their optimality under small perturbations of vector criterion parameters is considered. The formulas for estimating numerical measures of two types of stability are found.     

Outcome failures of endosseous implants from a clinical training center

In an effort to provide realistic clinical information from a "real-world" environment, the present retrospective study was undertaken to assess outcome failures after implant placement in a dental school clinical training center. A database was kept of the clinical information and was analyzed according to established parameters for implant outcomes. The demographics showed that over a period of 6 years, 80 different operators with a wide range of clinical experience had inserted 1,263 implants in a diverse patient pool of 380 individuals. Analysis of the outcomes showed a cumulative survival rate of 91.3%. The time of explantation, the type, size, and location of implants lost, and failure rates in smoking patients were also analyzed. The results indicated that the use of implants by operators with different levels of experience did not affect favorable outcomes.     

Freezing and thawing tests of liquid deicing chemicals on selected pavement materials

The extent of deterioration of portland cement concrete and several types of asphaltic concrete subjected to organic deicing chemicals was determined over 60 freezing-thawing cycles. Proprietary solutions containing urea, ethylene glycol, and formamide affected the surface of old air-entrained concrete only slightly (rating of 1 on a scale of 0 to 5 of increasing degradation). Asphaltic concrete specimens were not significantly affected. Abrasion tests were made on air-entrained concrete specimens exposed to ethylene glycol solution during freezing and thawing; material loss was very low, nearly the same as with a distilled water control.