Toward an understanding of aging in plutonium from direct measurements of stored energy

ABSTRACT

We present here the first direct measurement of the radiation-damage-induced energy stored in δ-phase plutonium. The primary mode of radioactive decay of ²³⁹Pu occurs with a time constant of τ=1.1?×?10¹²?s. Each decay imparts about 85?keV of recoil energy to the uranium byproduct, 5.2?Mev to the alpha particle, and a spectrum of mostly low energy gamma rays with the most probable at 51?keV [1]. Most of the decay energy is converted immediately to heat, releasing about 1.9?mW/g. However, some thermally-recoverable energy remains trapped. Reported here are measurements of that stored energy using differential scanning calorimetry (DSC) applied to ²³⁹Pu-2.0 at.%Ga δ-phase alloy. Retained energy of ～2 J/g saturates at about 5 months and is unchanged after 30 years. The magnitude of the stored energy agrees with a short-bond defect model that that we present here. This model treats radiation damage as a Pu impurity with shortened bond lengths. It explains the change in known properties with age and predicts that density increases with age, contrary to current thinking. The short-bond impurities proposed are expected to act like other impurities, affecting strength, phase transitions, grain boundaries and other metallurgical properties.     

Investigation of the interaction of He and D in FeBSi alloy

He and H can be produced by nuclear reaction. In addition, energetic particles of He and T and D, which are isotopes of H, in the plasma of fusion reactor induce the damage in the surface of materials, such as erosion, sputtering and blistering. To investigate the interaction of He and D, amorphous and crystalline FeBSi alloys were irradiated by He or D₂ or He?+?D₂ ions with 5?keV. The results of thermal desorption indicated that more He atoms were trapped in both the amorphous and crystalline alloy irradiated by He ions than D atoms in those alloys irradiated by D₂ ions. Although He and D atoms were trapped in FeBSi alloy irradiated by He?+?D₂ ions, desorption peaks of D₂ and He were separated. Absorption of D in an amorphous alloy was influenced by the presence of He; however, absorption of He was independent of D₂ irradiation in both alloys.     

中西医结合治疗儿童过敏性紫癜和预防相关肾损害的临床研究

过敏性紫癜是儿童常见的免疫系统疾病。西医治疗过敏性紫癜已形成常规模式,并有一定疗效,但也有一定局限性。本病易反复,易损伤肾脏,严重时可导致紫癜性肾炎。本文拟研究中西医结合方法治疗过敏性紫癜及预防肾脏损伤的临床效果。研究表明,中西医结合治疗该病存在一定优势,能有效治疗过敏性紫癜,并降低肾脏损害及紫癜性肾炎的发生率。但应看到本研究结论主要是通过临床经验取得,样本量小,未进行远期随访,缺乏系统深层次实验室论证,还有待进一步研究。     

骨髓捐献人中途拒捐的民事责任探析——基于信赖保护的视角

基于捐献行为的公益性、单务性和人身性,各国法律赋予捐献人任意撤销权,但是出于对捐献人允诺的信赖而改变自身处境的接受人利益也应该得到保护.从信赖保护的视角出发,在血型高分辨检测之前,捐献人一旦签订了捐献协议,即负有保护接受人信赖利益的义务,捐献人虽然有权中途拒捐,但应当承担信赖赔偿责任.     

The effects of stress on dna repair capacity

Abstract

Research has shown that lymphocytes of high-distress patients have reduced DNA repair relative to that of low-distress patients and healthy controls. Furthermore, deficits in repair are associated with an increased risk of cancer. Using and academic stress model, we hypothesized that students would exhibit lower levels of Nucleotide Excision Repair (NER) during a stressful exam period when compared to a lower stress period. Participants were 19 healthy graduate level students. NER was measured in lymphocytes using the unscheduled DNA synthesis (UDS) assay with slide autoradiography. Contrary to prediction, mean values for NER significantly increased during the higher stress period relative to the lower stress period controlling for background differences in repair. Furthermore, lymphocytes had significantly increased repair of endogenous damage during the higher stress period. Stress appears to directly increase DNA repair. Additionally, stress may increase DNA repair indirectly by increasing damage to DNA.     

食管癌术后急性肾衰竭的临床分析

为了探讨食管癌术后急性肾衰竭发生的原因及防治经验,回顾性分析13例术后发生急性肾衰竭食管癌患者的临床资料,并总结防治体会。结果显示患者平均年龄67.5岁,体重50.4千克,皆有严重的吞咽梗阻症状,其中8例术前发现低蛋白血症,3例术前有不同程度的肾功能不全;术后3天内出现急性肾衰竭,治疗纠正肾前性病因、利尿和改善肾血流灌...     

Aquinas's Opposition to Killing the Innocent and its Distinctiveness within the Christian just War Tradition

This essay argues that Aquinas's position regarding the killing of innocent people differs significantly from other representatives of the Christian just war tradition. While his predecessors, notably Augustine, as well as his successors, from Cajetan and Vitoria onward, affirm the legitimacy of causing the death of innocents in a just war in cases of necessity, Aquinas holds that causing the death of innocents in a foreseeable manner, whether intentionally or indirectly, is never justified. Even an otherwise legitimate act of just war cannot legitimate causing the death of innocent people, as this can never advance the common good. This stance also contrasts sharply with much modern and contemporary double effect theorizing in relation to jus in bello. In this regard, Aquinas's position, shaped decisively by his biblical and theological commitments, may point the way towards an ethical orientation beyond the typical divisions of “pacifism” and “just war.”     

Cities and the real world

It is generally recognized that modern cities pose many problems for their inhabitants and contribute to environmental damage. However, neither planners nor scientists give adequate consideration to cities’ place in the evolutionary process and the planet's ecological system. By recognizing these connections and natural laws, planning would become more realistic, and meaningful progress could be made in solving serious social and environmental problems. Some basic problems influencing urban form are discussed, and a schematic example of how we might approach the planning of urban settlements is presented.