化学镀锡添加剂对镀层厚度及表面形貌的影响

采用电化学等方法研究了硫酸镍和水合肼对化学镀锡层厚度及表面形貌的影响.结果表明,硫酸镍起到了细化镀层的作用.而水合阱的加入使镀锡层的厚度增加.     

大口径高温高压管道下沉分析

以某电厂的主蒸汽管道为例,对其支吊架进行冷、热态检验,发现炉侧连续恒力吊架冷态时指针卡死下极限位置,热态时实际垂直热位移值较小,与设计严重不符。根据现场情况和应力计算结果综合分析,发现管道壁厚存在严重误差导致管道下沉。针对以上情况,首次提出了支吊架配置改造方案需要考虑的4个方面,给解决此类问题提供帮助。     

Fetal cardiac scanning today

The ability to examine the structure of the fetal heart in real-time started over 30 years ago now. The field has seen very great advances since then, both in terms of technical improvements in ultrasound equipment and in dissemination of operator skills. A great deal has been learnt about normal cardiac function in the human fetus throughout gestation and how it is affected by pathologies of pregnancy. There is increasing recognition of abnormal heart structure during routine obstetric scanning, allowing referral for specialist diagnosis and counselling. It is now possible to make accurate diagnosis of cardiac malformations as early as 12 weeks of gestation. Early diagnosis of a major cardiac malformation in the fetus can provide the parents with a comprehensive prognosis, enabling them to make the most informed choice about the management of the pregnancy. Copyright © 2010 John Wiley & Sons, Ltd.     

First-trimester screening: dealing with the fall-out

The articles collected together in this issue describe first-trimester screening for a variety of complications. With the advance of both technology and research, early pregnancy screening is becoming ever more sophisticated and complex. While there are clear benefits to most women receiving early reassurance that their baby is developing as expected, there is no evidence to suggest that an earlier prenatal diagnosis has less long-term emotional impact than at later gestations. The poignancy of ultrasound images for many parents means that it can be especially difficult to manage the anxiety when an ultrasound marker is highlighted as potential cause for concern. They can then face a journey of anxiety-laden uncertainty, which can extend through much of the pregnancy, and even beyond. Professionals involved in screening need to recognise and acknowledge such adverse side-effects and develop the skills necessary to help parents understand and cope with the uncertainties inherent in the process. Copyright © 2011 John Wiley & Sons, Ltd.     

Increased nuchal translucency in euploid fetuses—what should we be telling the parents?

Nuchal translucency (NT) measurement between 11 and 14 weeks' gestation is an undisputed marker for aneuploidies. When conventional karyotyping is normal, enlarged NT is a strong marker for adverse pregnancy outcome, associated with miscarriage, intrauterine death, congenital heart defects, and numerous other structural defects and genetic syndromes. The risk of adverse outcome is proportional to the degree of NT enlargement. Although the majority of structural anomalies are amenable to ultrasound detection, unspecified genetic syndromes involving developmental delay may only emerge after birth. Concern over these prenatally undetectable conditions is a heavy burden for parents. However, following detection of enlarged NT the majority of babies with normal detailed ultrasound examination and echocardiography will have an uneventful outcome with no increased risk for developmental delay when compared to the general population. Counseling should emphasize this to help parents restore hope in normal pregnancy outcome and infant development. Copyright © 2010 John Wiley & Sons, Ltd.