228Ra in cow’s milk from an anomalous region of Pernambuco-Brazil

The counties of Pedra and Venturosa have one of the largest natural radioactive occurrences of Brazil. The large farms producing milk in the state of Pernambuco are located in these counties. The forage plants cultivated on those farms have high concentrations of ²²⁸Ra, a naturally occurring descending radionuclide from the ²³²Th series. The ²²⁸Ra is transferred to the forage plants, and once ingested by the lactating cow, this radionuclide is rapidly transferred to the milk. Thus, milk intake is an important route for ²²⁸Ra of incorporation by the human consumer and may induce the appearance of bone sarcoma. Accordingly, the aim of the present study was to determine the concentrations of ²²⁸Ra in milk produced in the Pedra and Venturosa farms, in order to estimate the risk of ingestion in the local population. The ²²⁸Ra was determined by actin-228 (²²⁸Ac) using the radiochemical technique of barium sulphate precipitate (BaSO₄). The milk samples had concentrations of ²²⁸Ra ranging from 61 to 1338 mBq.l^?1, which corresponded to the cumulative equivalent dose ranging from 0.04 to 0.1 Sv. Although the doses were low, regulatory and protective measures should be taken to study the radiotoxic effects of ²²⁸Ra in subjects in the public.     

Experimental investigation of lift enhancement by suction-assisted delayed separation of the boundary layer on NACA 0012 airfoil

In the aerodynamic industry, one of the major problems of interest is the lift enhancement without any increase in the drag. In this paper, an attempt is made to increase the lift coefficient by delayed boundary layer separation using suction at various points, also the study is carried out to identify the optimum location for suction which provides maximum lift augmentation. The experiment is conducted with selected suction pressures of 60, 70, 80, 90?kN/m² at different locations in the range of 40–75% of the chord length of the airfoil. Among the selected pressures, the lowest one at the 70% length provides maximum performance. The critical Reynolds number occurs at around 95% of the length instead of 45% of the length when the same experiment is conducted without suction. The suction also assists in the heat transfer enhancement over the airfoil surface.     

自组织分层金属掺杂类金刚石薄膜的研究进展

近年来,研究学者发现在沉积过程中,某些金属元素掺杂类金刚石薄膜时能够形成一种特殊的自组织分层纳米结构,这种纳米结构克服了人为调控多层薄膜的工艺复杂性及局限性,同时赋予了薄膜更加优异的性能。主要综述了国内外对金属掺杂类金刚石薄膜中自组织分层结构的影响因素、形成机理等方面的研究现状。详细阐述了金属类型及含量、沉积条件(脉冲频率、基体偏压、气流比、沉积温度、沉积时间)、沉积方法等参数对自组织分层结构的生成及富金属层厚、富碳层厚、层数等尺寸的作用规律。重点介绍了离子重排机理、金属催化机理、强离子辐照诱导机理和靶中毒机理四种自组织分层结构形成机理的特点,并探讨了目前研究工作中存在的一些不足,如自组织分层结构的形成机理尚不清晰。上述四种机理模型均具有一定的局限性,且如何设计工艺参数实现自组织分层结构的内在调控仍是一个科学难点。针对这些问题,提出了自组织分层结构碳基薄膜的未来研究方向。     

微波消解-丁二酮肟沉淀分离-EDTA返滴定法测定含镍生铁中镍

含镍生铁是不锈钢冶炼重要原材料,准确快速检测含镍生铁中镍含量对不锈钢冶炼质量控制及成本控制至关重要,而使用丁二酮肟重量法测定含镍生铁中镍需使用大量酸溶解样品,有时还需要对不溶性残渣进行熔融处理,过程繁琐。实验利用微波消解法处理含镍生铁样品,并通过丁二酮肟沉淀分离法使含镍生铁中镍与钴、铜有效分离,再使用EDTA返滴定法测定镍,最终建立了含镍生铁中镍含量的测定方法。使用5个含镍生铁标准样品进行验证,当镍质量分数为5%～20% 时,测定结果的相对标准偏差(RSD,n=7)为0.14%～0.33%;通过t检验法进行显著性检验,测定结果与标准值之间无显著性差异。分别按照实验方法和国标方法GB/T 31924—2015《含镍生铁 镍含量的测定 丁二酮肟重量法》对同一个含镍生铁样品进行检验,使用t检验对两种方法得到的结果进行统计分析,结果表明两种方法检验结果无显著性差异。     

Electrical blasting disintegration of copper-nickel ores conjointly with separation of particles by size

Absract The effect of electrical blast parameters is studied for grinding mineral materials by example of copper-nickel ore. It is shown that the average energy consumed by the electrical blasting is within 5–50 J/g. The particle disintegration mechanism has been considered at high and low electric conductivity of ore. It is established that grinding and separation of particles by size are possible to be performed conjointly in the same apparatus. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 1, pp. 100–107, January–February, 2007.     

湿法炼铜领域中的膜技术

结合典型应用实例，介绍用纳滤，反渗透，超滤，微滤，扩散渗析等膜分离解决铜溶剂萃取工艺中存在的低浓度含铜浸出液处理，水平衡控制与铜的浓缩，电解贫液处理，絮凝物等问题，并分析我国湿法炼铜工业中采用膜技术的前景。     

矾山磷矿尾矿回收铁试验研究

介绍了矾山磷矿磁选尾矿的矿物组成、铁的赋存状态、矿物嵌布特征以及用重选、重磁联合流程、磁选分别对其进行回收铁的试验研究情况。用磁选法粗选并进行粗精矿再磨再选，可获得含铁64．19％、回收率5．63％的铁精矿。     

我国磁选设备及铁矿石预选技术

介绍了目前我国磁选设备的研制及应用现状，并就干式弱磁选、强磁选和重选等工艺用于我国铁矿石预选的技术经济状况及推广应用价值进行了论述。     

鞍山地区贫赤铁矿选矿工艺新进展

通过对鞍山地区三大贫赤铁矿选矿厂的工艺流程和指标的介绍，分析了各选厂在工艺流程方面的各自特点及存在的一些问题，指出强磁机和扫中磁机的引入，稳定了工艺流程，提高了分选效率；粗粒重选有利于铁矿物的充分回收；阴离子反浮选保证了精矿品位合格。鞍山地区贫赤铁矿工艺流程的成功应用，为我国贫赤铁矿选矿开辟了一条新的途径。     

白云鄂博中贫氧化矿磁选新工艺综合回收铌的研究

根据铌矿物与其它有用矿物、脉石矿物的磁性差异,采用弱磁—强磁选工艺将包头白云鄂博中贫氧化矿中的铌有效地富集于强磁中矿。本文还介绍了从强磁中矿浮选回收铌的药剂制度及工艺条件,论述了浮选药剂的主要作用。采用强磁中矿直接浮选铌和强磁中矿先浮选稀土后浮选铌均取得较好指标,得到的铌精矿能满足高炉—转炉—电炉—电炉提铌工艺对原料的要求。