Magnetic pulse welding: Interface of Al/Cu joint and investigation of intermetallic formation effect on the weld features

This paper attempts to highlight emerging issues when joining dissimilar metal pairs by magnetic pulse welding. For this purpose, joint of Al/Cu and Al/Al welded with the same parameters are compared. Al/Cu combination involves a formation of an interfacial intermetallic phase whereas Al/Al joint is bonded by metal continuity at the interface. The intermetallic is found to be amorphous, nanoporous, and damaged by a multi-directional cracks. The formation of such features is respectively explained by a melting confined at the interface followed by high rate cooling, cavitation phenomenon and solidification shrinkage. Mechanical characterizations of the Al/Cu joint show brittle fracture at the interface with fragmentation of the [0] intermetallics (glass type rupture). The intermetallic defects such as pores and cracks strongly reduce the breaking load level when compared to the Al/Al case. On the other hand, the Al/Al joint shows ductile fracture with plastic deformation of the interface.     

高梯度磁除尘的实验研究

对磁性粉尘和非磁性粉尘进行了磁分离实验研究。结果表明,对磁性粉尘,磁除尘效率可达99％以上,而对非磁性粉尘,通过粉尘上磁,磁除尘效率可达90％以上。     

镁-铝水滑石的制备及其脱色性能

以不同的Mg^2＋与Al^3＋摩尔比制备一系列的镁-铝水滑石，考察镁-铝水滑石对单一品种模拟分散染料废水的脱色效果。实验结果表明，以n（Mg^2＋）：n（Al^3＋）为3：1制得的镁-铝水滑石对模拟分散染料废水的脱色效果最好；脱色处理后的镁-铝水滑石再生后可重复使用，它对模拟分散染料废水的脱色效果与新的镁-铝水滑石的脱色效果几乎没有差别；在模拟分散染料废水pH为10～11、镁-铝水滑石的加入量为1.0g／L、反应2h的条件F，模拟分散染料废水的脱色率为98％。     

Magnetic resonance imaging of the fetus: A study of 20 cases performed without curarization

Twenty patients underwent magnetic resonance imaging (MRI) at a mean gestational age of 32 weeks. There were 12 patients with suspected fetal brain abnormality and four with intrauterine growth retardation (IUGR), while the remaining four cases were studied for other reasons. The MRI examinations were performed on a 0.5 Tesla machine, with surface coils. One minute acquisition time T1 sequences were used. All the studies were performed without fetal curarization, and only under maternal sedation using flunitrazepam given per os 1 h before MRI examination. Three examinations were incomplete because of fetal movement artefacts. In the remaining cases, MRI allowed the examination of fetal brain anatomy. In five cases, it helped to differentiate isolated hydrocephalus and corpus callosum agenesis. Sub-ependymal nodules were depicted in a case of fetal tuberous sclerosis. One suspected arachnoid cyst was proved to be an ultrasound artefact. Decreased fetal fat on MR images was correlated with low birth weight in cases of IUGR. Due to its better spatial resolution, ultrasonography was more accurate for the diagnosis of facial and lumbar anomalies. Fetal MRI may be performed without curarization. Surface coils allow the detailed analysis of brain parenchyma, and thus MRI is especially useful in the difficult prenatal diagnosis of fetal brain abnormalities.     

Seasonal comparison of moss bag technique against vertical snow samples for monitoring atmospheric pollution

This is the first study seasonally applying Sphagnum papillosum moss bags and vertical snow samples for monitoring atmospheric pollution.Moss bags,exposed in January,were collected together with snow samples by early March 2012 near the Harjavalta Industrial Park in southwest Finland.Magnetic,chemical,scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDX),K-means clustering,and Tomlinson pollution load index(PLI)data showed parallel spatial trends of pollution dispersal for both materials.Results strengthen previous findings that concentrate and slag handling activities were important(dust)emission sources while the impact from Cu–Ni smelter's pipe remained secondary at closer distances.Statistically significant correlations existed between the variables of snow and moss bags.As a summary,both methods work well for sampling and are efficient pollutant accumulators.Moss bags can be used also in winter conditions and they provide more homogeneous and better controlled sampling method than snow samples.     

高梯度磁场中磁性可吸入颗粒物脱除试验研究

在高梯度磁场中,分别对钡铁氧体、Fe3O4和γ-Fe2O3等3种磁性可吸入颗粒物进行了脱除实验研究.通过改变外加磁场磁通密度、格栅排数、气溶胶流量、磁性可吸入颗粒物的种类,研究其脱除效率的变化规律.确定影响磁性可吸入颗粒物脱除效率的因素.结果表明:外加磁场的磁通密度越大,颗粒物的脱除效率越高,但有一定限度;格栅排数增加后,颗粒物的脱除效率得到提高;随着流量的增加,颗粒物的脱除效率有所下降;磁性颗粒的磁化率越大.颗粒脱除效率越高.     

Do bearing magnets affect the extent of deflection in clock-shifted homing pigeons?

When released after clock-shift, homing pigeons fail to orient towards the home direction but display a consistent deflection of their initial orientation due to the difference between the real sun azimuth and the computed azimuth according to the subjective time of each single bird. It has been reported that the size of the observed deflection is frequently smaller than expected and a discussion on the possible factors affecting the size of deflection has emerged. Some authors have proposed that the major factor in reducing the deflection after clock-shift is the simultaneous use of both the magnetic and the sun compasses, giving true and erroneous information, respectively, about the home direction. Therefore, a magnetic disturbance, by impeding the use of the geomagnetic information in determining the home direction, is presumed to increase the size of the deflection up to the levels of the expectation. To test this hypothesis, we released three groups of clock-shifted birds from unfamiliar locations (unmanipulated pigeons, pigeons bearing magnets on their head, and pigeons bearing magnets on their back) together with a group of unshifted control birds. As no difference in the orientation of the three groups emerged, we were not able to confirm the hypothesis of the role of the magnetic compass in reducing the expected deflection after clock-shift.Communicated by W. Wiltschko     

Prenatal diagnosis of a craniopharyngioma using ultrasonography and magnetic resonance imaging

We report an infant with a craniopharyngioma which was detected in utero. Maternal uterine ultrasonography, done at 27 weeks because of polyhydramnios, revealed a 4 cm midline mass near the base of the fetal skull. At 31 weeks, magnetic resonance imaging of the maternal abdomen confirmed the presence of a mass in the region of the third ventricle and revealed hydrocephalus. Two days post-partum a computed tomography (CT)-guided needle biopsy of the mass was performed and recovered tissue which was histologically consistent with a craniopharyngioma. The infant' s postnatal period was complicated by seizures, which were treated with phenobarbital, and by progressive hydrocephalus, necessitating placement of a ventriculo-peritoneal shunt. He also received therapy for central hypothyroidism and diabetes insipidus. The infant' s parents refused permission for attempted resection of the tumour and he died at 8 weeks of age. This represents the second reported case of an antenatally detected craniopharyngioma. Four other cases of different intracranial tumours have been detected in utero using ultrasound, with no reported survivors past 3 days of age. There is a uniformly poor prognosis of such infants, but earlier diagnosis and intervention may change this result.     

催化裂化催化剂的磁分离及再生回用技术的发展

重点介绍了国内外关于催化裂化平衡催化剂的化学再生方法（ＤＥＭＥＴ工艺）与物理分离方法（磁分离工艺）的机理、工艺及应用现状，提出了上述工艺在我国应用的前景及方向。     

磁场协同Ca2O2/Fe2+处理活性红染料废水的实验研究

利用磁场协同Ca2O2/Fe2 催化氧化体系处理活性红染料废水,研究不同磁化时间、磁场强度和催化氧化各种影响因素下对活性红染料模拟废水的去除率.结果表明:在pH值为3,C(FeSO4·7H2O)=50 mg,C(Ca2O2)=1.45g条件下,反应20min,去除率达62.5%.外加磁场磁场强度为427.8 mT的作用下,磁化反应20 min,CODCr的去除率提高了8.3%.