鼻泪管疏通术中用恒磁吸引器放置填塞物

鼻泪管疏通术或称鼻泪管阻塞切除术治疗慢性泪囊炎已有报导。我院自1987年8月开展此项手术,至今已做14例,治疗效果也较满意。作者观察到鼻泪管疏通术中是否留置填塞物,对疗效有很大影响。我们最初3例术中没留鼻泪管填塞物,虽然术后每日用糜蛋白酶冲洗泪道,但其中第2例术后3天鼻泪道重新堵塞,经冲洗探通均无效。第3例术后4天发生堵塞,再次手术探查鼻泪道,清除血痂,置入硅胶管填塞。自第4例起,均用硅管作填塞物,术后一周拔管,

钡铁氧体磁粉的静电分散

钡铁氧体是一种应用广泛的功能材料。对于原料粉体而言,当钡铁氧体粒子减小到微纳米量级时,其性能可以得到显著的提高。但超微磁性粒子之间团聚现象比一般粉体更为严重,往往导致超微粉体的优良特性发挥不出来。实际应用中为了克服团聚,需要对粉体进行适当的分散处理。本文以荷电电压、荷质比为考察指标,用RISE-2006粒度分析仪对静电分散后钡铁氧体粒子的粒度进行了检测,并以此来表征粉体的分散性能。实验结果表明,静电分散后粉体的平均粒度明显变小,在26℃、空气相对湿度为45%、电压为40kV时,静电分散的效果最好,此时粉体颗粒间的静电斥力大于范德华力和磁吸引力之和,且静电分散作用可保持6h左右。

椭球的磁化状态对磁选的影响

通过计算磁场里的铁磁性椭球内部及外部的磁场,说明了随着椭球材料磁导率的减小,椭球的聚磁能力下降,同时为提高磁场吸引矿粒的力所需增加的电耗更多。

牛网胃内金属异物探测及取出试验

用金属探测器对两个奶牛场259头奶牛体表网胃区进行探测,阳性率占被检牛的70.7%,表明这两个奶牛场奶牛的网胃内普遍存在金属异物,并且阳性率随其年龄增长而增高。对41头阳性奶牛用恒磁吸引器进行网胃取铁,多数牛经两次取铁后变为阴性(阴性率为92.7%)。饲料检查结果表明,青贮和糟渣类饲料中普遍存在金属异物。对牛群进行定期探测和取铁,是防止网胃内金属异物引起内脏器官损伤性疾病发生的有效预防措施和手段。

神奇的稀土元素

被称为当代永磁王的钕铁硼,具有极强的磁吸引力,它比通常的铁氧体磁力强十倍,甚至能吸引比自身重量重600倍的物体。一大堆铁球,一下就被一小块钕铁硼磁体吸起来了。钕铁硼之所能有此具大的磁吸引力,是它本身有大的矫顽力决定的。

法国国营铁路试验涡流制动

在平道上以350 km/h速度运行的新一代TGV必须使停车距离保持在9000 m,即平均制动减速度为0.5 ms^2。涡流制动是一种与粘着无关的、无磨损的制动方式。列车磁铁与钢轨之间足够快的相对运动感应出电流,由此又产生磁吸引力,其水平分力使列车减速。存在的问题是垂向的分力和钢轨发热。

Magnets, children and the bowel: A dangerous attraction?

Reports of magnet ingestion are increasing rapidly globally. However, multiple magnet ingestion, the subsequent potential complications and the importance of the early identification and proper management remain both under-recognized and underestimated. Published literature on such cases could possibly represent only the tip of an iceberg with press reports, web blogs and government documents highlighting further occurrence of many more such incidents. The increasing number of complications worldwide being reported secondary to magnet ingestion point not only to an acute lack of awareness about this condition among the medical profession but also among parents and carers who will be in most cases the first to pick up on magnet ingestion. There still seems to be no consensus on the management of magnet ingestion with several algorithms being proposed for management. Prevention of this condition remains a much better option than cure. Proper education and improved awareness among parents and carers and frontline medical staff is key in addressing this rapidly emerging problem. The goal of managing such cases of suspected magnet ingestion should be aimed at reducing delays between ingestion time, diagnosis time and intervention time.

磁铁变魔术

古时候,人们对磁吸引铁块,感到非常惊奇。当时,古人看到这些现象后,简直觉得这是神在变魔术。现在,我们利用磁铁也能变一个魔术,不信请按照下面的步骤来做。