General 2.5 power law of metallic glasses

Metallic glass (MG) is an important new category of materials, but very few rigorous laws are currently known for defining its “disordered” structure. Recently we found that under compression, the volume (V) of an MG changes precisely to the 2.5 power of its principal diffraction peak position (1/q₁). In the present study, we find that this 2.5 power law holds even through the first-order polyamorphic transition of a Ce₆₈Al₁₀Cu₂₀Co₂ MG. This transition is, in effect, the equivalent of a continuous “composition” change of 4f-localized “big Ce” to 4f-itinerant “small Ce,” indicating the 2.5 power law is general for tuning with composition. The exactness and universality imply that the 2.5 power law may be a general rule defining the structure of MGs.Metallic glasses (MGs) possess many unique and superior properties, such as extremely high strength, hardness, and corrosion resistance, etc., making them promising metallic materials with widespread applications (1, 2). Thousands of MGs with a wide range of compositions and properties have been synthesized over the past decades. However, so far the development of MGs is mainly based on tedious composition mapping in multicomponent space to pinpoint the combination of elements with optimized glass-forming ability (GFA). This method for development of MGs is a time- and resource-intensive strategy of trial and error which highlights the need for the guidance of a general theory (2, 3). Intensive research effort has been devoted to finding general rules in various MGs to understand the fundamentals and to guide the development of new MGs (4, 5). Quantitative correlations between their properties have been observed. For instance, compressive yield strength and elastic moduli of MGs are found to be intimately connected with their glass transition temperature T_g (6–10), and the ductility, fragility (11, 12), and Poisson’s ratio of MGs are closely related (13–16). The extensive correlations in properties suggest that the disordered MGs may share general rules in their structure. To clarify this scenario, detailed and accurate structural information spanning short range to long range is required. However, the current experimental probes and theories are limited to local structure in MGs (17). Therefore, understanding how the atoms efficiently fill up the 3D space and how this controls the bulk properties of MGs remains a long-standing theoretical challenge (18–23). To date, few general and exact rules regarding structure–property relationships have been established in MGs (23).Encouraging progress on understanding structure–property relationships in MGs has recently been made through the discoveries of the noncubic (2.3 or 2.5) power laws that correlate the principal diffraction peak (PDP) position q₁ with the bulk density ρ or average atomic volume, V_a, i.e., ρ∝(q₁)^D or V_a∝(1/q₁)^D, where D equals ∼2.3 with varying the composition of MGs at ambient pressure (19) or ∼2.5 for tuning the density of MGs with pressure (22, 24). Whereas composition and pressure show similar exponents in the power laws in MGs, composition and pressure are two independent variables for controlling the density (volume) of materials; they usually have dramatically different effects on MGs. For example, pressure is thought to cause only elastic densification in MGs without obvious structural change because of their already densely packed structure; the structure and properties of MGs are very sensitive to even minor compositional variations (25, 26). In addition, to achieve composition change, different samples usually have to be synthesized. And, many other variables are thought to be inevitably involved, making the compositional change complex (23). Therefore, some basic questions have been perplexing to the glass community: Why do “complex” compositional and “simple” pressure power laws show similar exponents? Is there any connection between them? These questions remain unanswered and have been the major obstacle in understanding the nature of these noncubic power laws.To address these questions, a systematic study in the 2D pressure-composition space seems to be required. However, the consistency of the data in this kind of study will be questionable. Alternatively, in the present study, we choose the polyamorphous Ce₆₈Al₁₀Cu₂₀Co₂ MG as a model system. It is well known that Ce-based MG systems show a polyamorphic transition between ∼2 GPa and ∼5 GPa caused by the pressure-induced 4f electron localized-to-itinerant transition (27, 28). During this polyamorphic transition, both the atomic size and the electronegativity of Ce are significantly changed (29). Composition tuning in MGs mainly means the variation of atomic size and electronegativity of components, which controls the formation of MGs (30). Therefore, although nothing changes in the nucleus, for MGs this pressure-induced polyamorphic transition is equivalent to a continuous “composition” change with the 4f-localized “big Ce” gradually substituted by 4f-itinerant “small Ce.” As a result, we are able to vary both pressure and composition of a MG in a well-controlled way for the first time, to our knowledge.     

唐氏综合征合并桥本毒症、反复脑梗死1例并文献复习

目的通过1例唐氏综合征(DS)合并桥本毒症、反复脑梗死的报道,探讨DS合并脑梗死可能的机制。方法详细介绍1例10岁DS患儿合并桥本氏甲状腺炎、甲状腺毒症(HTT)和反复脑梗死的诊断治疗过程,系统检索文献并复习已报道的类似病例,汇总DS合并脑梗死病例的临床特征。结果 10岁女童,以"消瘦,无力,多汗4月余"主诉入院,既往曾检查染色体核型47,XX,+21,诊断DS。入院后查甲状腺功能提示TPOAb明显升高、TRAb正常,TSH降低,抗双链DNA抗体1∶101(+),抗组蛋白抗体1∶101(+),MPO 1∶101弱(+),PR3 1∶101弱(+),诊断为HTT。予抗甲状腺等治疗后好转出院。2月余后无明显诱因2次发生肢体无力、行走困难,MRI分别提示左侧和右侧脑梗死。予康复、抗凝、抗炎和抑制免疫治疗后,肌力恢复正常,随访1年患儿病情稳定。从Web of science、Pub Med数据库、中国知网和万方数据库系统检索DS合并脑梗死的相关文献共19篇,汇总17例DS合并脑梗死病例,41.2%合并感染,52.9%合并Moyamoya病,23.5%合并甲状腺功能异常,47.1%伴有自身抗体阳性,DS合并脑梗死总体预后较好。结论 DS合并桥本毒症、反复的脑梗死少见,但对生存时间较长的DS患者需要关注自身免疫性疾病发生的可能。     

湖南省县级血吸虫病诊断网络实验室能力建设调查

目的调查湖南省县级血吸虫病诊断网络实验室建设水平和运行情况,为完善全省血吸虫病诊断网络体系提供参考依据。方法按照国家县级血吸虫病诊断网络实验室建设标准和要求,采用自查、自评和现场评审相结合的方式,对湖南省县级血吸虫病诊断网络实验室的建设水平与运行情况进行评估。结果湖南省依托41个国家级血吸虫病监测点建设的县级血吸虫病诊断网络实验室中,有36个符合国家血吸虫病诊断网络实验室建设要求,获得了省级血吸虫病诊断网络实验室准入资质。3家县级血吸虫病诊断网络实验室参加的6批次国家血吸虫病诊断参比中心室间比对均获得"完全一致"评价;血清学和病原学检测样品复核检测符合率分别达98.40%和100%。结论湖南省已初步建成血吸虫病诊断网络实验室体系并有效运行,但其建设水平仍待进一步完善和加强。     

危害行为风险评估和护理干预在流浪精神障碍患者中的应用

目的 探讨危害行为风险评估和护理干预对流浪精神障碍患者的应用效果。 方法将115例流浪精神障碍患者按住院号的单双数分为研究组和对照组,研究组58例实施危害行为风险评估和基于危害行为风险评估的护理干预,对照组57例实施常规护理干预。分别于干预前和干预3个月后比较2组WHO残疾评定量表Ⅱ(WHO-DAS Ⅱ)评分和观察危害行为发生情况。 结果 干预前,2组WHO-DASⅡ总分、各领域因子得分及危害行为发生率比较,差异无统计学意义;干预后,研究组的WHO-DASⅡ总分及理解与交流、自我照料、生活活动、社会参与的因子得分均低于对照组;研究组的吵架斗殴、吐痰、毁物、色情行为的发生率低于对照组。 结论 基于危害行为的风险评估和护理干预对流浪精神障碍患者的理解与交流、自我照料、生活活动、社会参与等领域的功能有改善作用,有利于防止患者发生危害行为。     

赋能理论对剖宫产术后产妇早期离床活动的影响

目的 探讨赋能理论对剖宫产术后产妇早期离床活动的影响。 方法 选取符合入选标准的剖宫产产妇400例,按剖宫产手术顺序单双号分为观察组与对照组各200例。对照组采取剖宫产术后常规护理,观察组采用赋能模式护理。比较2组产后24h内离床率、肠鸣音恢复时间及产后48h纯母乳喂养率。 结果 观察组产后24h内离床率及48h纯母乳喂养率明显高于对照组(χ²=29.421,P<0.001; χ²=48.000,P<0.001),肠鸣音恢复时间明显短于对照组(t=16.474,P<0.001)。 结论 将赋能理论应用于剖宫产围手术期护理,能有效地促进产妇早期离床及快速康复,提升纯母乳喂养率。     

Impact of different annuloplasty rings on geometry of the mitral annulus with fibroelastic deficiency: the significance of aorto–mitral angle

We sought to investigate the impact of full annuloplasty rings versus C-shape bands on mitral annular geometry in the presence of fibroelastic deficiency (FED), as assessed by intraoperative three-dimensional transesophageal echocardiography (3DTEE). We retrospectively selected 65 patients who underwent mitral valve repair for severe mitral regurgitation caused by FED using full rings (the Ring group, n?=?30) and C-shape bands (the Band group, n?=?35). 71 controls without valvular heart disease were also included. Thorough 3DTEE inspections were performed for the entire cohort to measure morphological parameters of mitral annulus before and after surgery. Mid-term repair durability and left atrial diameter were followed up. The preoperative 3DTEE parameters, including annular diameters, area, height and aorto–mitral angle, were significantly larger in the FED groups than normal, and were comparable between two groups using different annuloplasty devices. After repair, the anterior–posterior diameter, annulus circumference and area were significantly larger in the Band group than in the Ring group. The aorto–mitral angle became comparable with normal value in the Ring group (p?=?0.728), but not in the Band group (p?=?0.011). Follow-up echocardiographic data showed a significant correlation between postoperative aorto–mitral angle and reduced left atrial diameter at 50.3 months after surgery (r?=?0.63; p?<?0.001). In conclusion, compared with C-shape bands, full rings may impose less narrowing on aorto–mitral angle, which correlates well with mid-term left atrial reverse remodeling.     

震荡法在纠正EDTA依赖的假性血小板减少中的应用

目的:评估震荡法纠正EDTA依赖的假性血小板减少(EDTA-dependent pseudothrombocytopenia,EDTA-PTCP)的可行性。方法:收集140例EDTA-PTCP血标本,比较震荡前后全自动血细胞分析仪血小板计数检测结果,同时进行外周血涂片以观察血小板分布情况。结果:140例EDTA-PTCP血标本中,93例外周血涂片显示震荡后血小板聚集明显减少,血小板计数中位数为184×10~9/L,与震荡前(33×10~9/L)差异有统计学意义(P0.05);另47例为未完全解聚标本血小板计数中位数为48×10~9/L,与震荡前(39×10~9/L)差异无统计学意义。140例EDTA-PTCP标本中,震荡前后其他参数差异均无统计学意义。20例正常抗凝血标本震荡前后各项参数差异均无统计学意义。结论:震荡法可纠正多数EDTA-PTCP,是一种简单、有效的方法,可以提高检测效率,减轻患者痛苦。     

Serum miRNA profiling identifies miR-150/30a as potential biomarker for workers with damaged nerve fibers from carbon disulfide

As crucial small regulatory molecules, serum microRNAs (miRNAs) have been widely identified as potential noninvasive biomarkers. To survey and identify serum miRNAs associated with workers who had experienced injury to their nerve system from carbon disulfide (CS₂), we profiled abnormally expressed miRNAs using the microarray technique and further performed qRT-PCR validation in case and control samples (n=20). Microarray profiling in pooled RNA samples showed that many miRNAs in workers exposed to CS₂ were aberrantly expressed. Based on control samples exposed to CS₂, a great amount of abnormal miRNAs, including some miRNA gene clusters and families, were obtained from microarray datasets. Most of deregulated miRNAs were up-regulated, and almost all miRNAs showed consistent expression patterns between workers with different numbers of damaged nerve fibers. Functional enrichment analysis suggested that these abnormal miRNAs showed versatile roles by contributing to multiple biological processes. Some aberrantly expressed miRNAs were characterized as miRNA gene clusters or families, and they always showed consistent expression patterns. miR-150 and miR-30a were selected to be further validated by qRT-PCR as up-regulated species, and they could discern case samples from control samples. miR-150 and miR-30a may be potential noninvasive biomarkers for a damaged nervous system.     

北京市2013－2014年肠道门诊腹泻患者中诺如病毒感染的流行病学及临床特征分析

目的 了解北京市肠道门诊腹泻患者诺如病毒感染的流行状况及临床特点。方法 采集2013年4月至2014年3月北京市肠道门诊1 892名腹泻患者粪便标本, 并收集患者的流行病学及临床症状资料。使用real time RT-PCR对诺如病毒核酸进行检测, 采用描述性流行病学方法进行分析。结果 2013年4月至2014年3月北京市肠道门诊腹泻患者诺如病毒阳性率为14.2%(269/1 892);寒冷月份阳性率较高;怀柔区、延庆县等西北部山区阳性率较高;6月龄至5岁儿童诺如病毒阳性率高于其他年龄组, 差异有统计学意义(P=0.006), 散居托幼儿童诺如病毒阳性率高于其他职业人群, 差异有统计学意义(P=0.025);诺如病毒阳性腹泻患者恶心、呕吐症状发生率高于阴性患者, 差异有统计学意义(P<0.05)。结论 诺如病毒是肠道门诊腹泻患者的重要病原, 6月龄至5岁腹泻儿童诺如病毒感染率高于其他人群, 恶心、呕吐为诺如病毒感染的常见症状。