粉末冶金高强韧钛合金的界面反应层研究

采用预合金粉末热等静压(hot isostatic pressing ,HIP)近净成形工艺制备了一种新型高强韧钛合金,研究了钛合金与低碳钢包套的界面反应。结果表明,钛合金与低碳钢包套之间存在波浪状的界面反应层,其厚度为8μm,钛合金中的合金元素Al、Mo和V向低碳钢中发生了一定程度的扩散,而两种材料的基体元素Ti和Fe发生扩散的程度要明显低于前者;通过选择性化学洗可以将包套去除,并将反应层厚度减少2.5μm,但微观上仍存在波浪状反应层;通过后续的喷砂处理可以进一步减小反应层厚度,并且使界面反应层平直。     

钪对7005铝合金组织性能的影响

采用金相、透射电镜、扫描电镜、拉伸试验等测试手段，研究了不同含量的稀土元素钪对７００５铝合金组织性能的影响。加入适量钪合金化可以明显细化合金组织，改变主要强化相η相的尺寸、形态、分布，减小晶界无沉淀带宽度，可以明显提高合金强度、塑性以及高温稳定性，这是合金中析出了与铝在体完全共格的Ａｌ３Ｓｃ（ｆｃｃ，α＝０．４１ｍｍ）质点所致。     

An accurate real-time PCR test for the detection and quantification of cauliflower mosaïc virus (CaMV): applicable in GMO screening

Maher Chaouachi and Marie Noelle Fortabat are contributed equally to this work.     

Dysregulation of Oxygen Sensing/Response Pathways in Pregnancies Complicated by Idiopathic Intrauterine Growth Restriction and Early-Onset Preeclampsia

Preeclampsia (PE) and intrauterine growth restriction (IUGR) are the leading causes of maternal and fetal morbidity/mortality. The central deficit in both conditions is impaired placentation due to poor trophoblast invasion, resulting in a hypoxic milieu in which oxidative stress contributes to the pathology. We examine the factors driving the hypoxic response in severely preterm PE (n = 19) and IUGR (n = 16) placentae compared to the spontaneous preterm (SPT) controls (n = 13) using immunoblotting, RT-PCR, immunohistochemistry, proximity ligation assays, and Co-IP. Both hypoxia-inducible factor (HIF)-1α and HIF-2α are increased at the protein level and functional in pathological placentae, as target genes prolyl hydroxylase domain (PHD)2, PHD3, and soluble fms-like tyrosine kinase-1 (sFlt-1) are increased. Accumulation of HIF-α-subunits occurs in the presence of accessory molecules required for their degradation (PHD1, PHD2, and PHD3 and the E3 ligase von Hippel–Lindau (VHL)), which were equally expressed or elevated in the placental lysates of PE and IUGR. However, complex formation between VHL and HIF-α-subunits is defective. This is associated with enhanced VHL/DJ1 complex formation in both PE and IUGR. In conclusion, we establish a significant mechanism driving the maladaptive responses to hypoxia in the placentae from severe PE and IUGR, which is central to the pathogenesis of both diseases.     

玄武岩纤维在钻探机具中的应用研究与展望

针对铝合金钻杆材料耐磨性差和耐腐蚀性差,以及坚硬地层钻进难等钻探难题,本文研究了玄武岩纤维对7075铝合金钻杆材料和WC基金刚石复合材料的性能影响,通过粉末冶金和热压烧结制备了铝基复合材料和胎体,并对其性能进行测试和研究。结果表明,玄武岩纤维/7075铝基复合材料的力学性能和耐腐蚀性能得到提升,玄武岩纤维的加入降低了胎体的磨耗比,提升了胎体的密实度、导热系数和金刚石把持力。本文还对玄武岩纤维在套管和油管领域的应用研究进行了总结和展望。     

从低品位铀多金属矿中综合回收铅和铁技术研究

华阳川铀多金属矿中有价金属品位均较低,通过选矿大幅度提高铀品位并综合回收伴生金属,方可使该矿床具备开发价值。针对矿石中伴生的铅和铁,开展了综合回收选矿试验研究,首先通过重选将各有价金属预富集在重选精矿中,然后采用铅硫混合浮选—铅硫分离工艺回收铅,通过添加铀矿物抑制剂、强磁脱铀等方式降低铅精矿中铀含量,最后采用弱磁选从选铅尾矿中回收铁,通过多次精选提高铁品位、降低铀含量。最终获得的铅精矿中铅品位67.19%、铀含量0.004%;铁精中铁品位66.50%、铀含量0.004%,经检测铅精矿、铁精矿和重选尾矿中的放射性均达标,铅精矿和铁精矿可以直接出售,重选尾矿可以按照普通尾矿处置。     

Evaluation of technetium transmutation in the experimental fast reactor “JOYO”

In this study the effectiveness of transmutation for the long lived fission product technetium-99 in the experimental fast reactor “JOYO” is evaluated. The cluster of reflector subassembly was replaced with a new moderator and target subassembly. The Beryllium metal is selected as moderator. The calculation of Ruthenium concentration evolution under irradiation was performed using ChainSolver 2.20 code. For 140 full power irradiation days, the transmutation yield is ∼30% and 87% in the radial reflector and target subassembly, respectively. The approximation used for the transmutation calculation is the assumption that the influence of change in irradiated materials structures on the reactor operator mode characteristics is insignificant.     

Probability-based design standards of structures

The process of developing probability-based codes in the past three or four decades has been applied in rules in the deterministic form of partial reliability factors. The situation in North America and western Europe is very well known. Our paper partially reviews developments in middle and eastern Europe and presents some examples of results. In accordance with the paper (Ellingwood, B. R., Probability-based codified design: past accomplishment and future challenges. Structural Safety, 1994, 13, 159–176.) it advocates a preparation of international rules for the direct use of reliability methods in structural design.     

Crystal structure of Gd<Subscript>14</Subscript>Cu<Subscript>48</Subscript>Ga<Subscript>3</Subscript> and Tb<Subscript>14</Subscript>Cu<Subscript>48</Subscript>Ga<Subscript>3</Subscript>

The compounds Gd₁₄Cu₄₈Ga₃ and Tb₁₄Cu₄₈Ga₃ have been synthesized, and their structures have been determined by powder x-ray diffraction (Gd₁₄Ag₅₁ type).     

Rod milling and thermal annealing of graphite: Passing the equilibrium barrier

The change in graphitic carbon structure induced by mechanical milling has been monitored by Raman spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction. It is well known that progressive rod milling of graphite results in an increase in structural disorder. Here, it has been found that a milling time of around 80 h is crucial in producing maximum nanocrystallite formation and this affects the nature of the products formed before or after annealing. At about 80 h equilibrium forms and no further production of nanocrystallites is possible although if additional energy is added amorphous carbon begins to form. Annealing produces different nanographitic carbons depending on the milling conditions because the material may be milled to an equilibrium concentration of nanocrystallites or less, or with additional energy transformed further past equilibrium to new product. Linear morphological structures and trace amounts of carbon nanotubes were found on milling for 80 h and annealing, but concentric layers of carbons were observed in samples milled as long as 240 h.