Compression and energy absorption behavior of high entropy alloy syntactic foams

金属空心微球泡沫材料由于具有轻质，高比强度，高吸能性能等特点被广泛应用于轻质结构和吸能材料领域。因此，研发更高强度和吸能性能的金属空心微球泡沫材料并对其变形失效和吸能机理进行研究具有重要意义。本论文采用高熵合金作为基体，Al2O3空心陶瓷微球作为填充颗粒，利用渗流铸造法研发了两种新型金属空心微球泡沫材料，并对它们的静动态力学性能及变形破坏宏微观机理展开了系统的研究工作，取得的主要创新成果如下： （1）探索并优化了利用渗流铸造法制备高熵合金空心微球泡沫的工艺，确定了优选的预热温度及渗流压力。成功制备出CoCrFeMnNi高熵合金泡沫材料和AlCoCrFeNi2.1共晶高熵合金泡沫材料。 （2）研究了CoCrFeMnNi空心微球泡沫室温下的准静态压缩力学性能，发现其在具有高强度的同时显示出极高的能量吸收能力，超过几乎所有已报道的同类金属泡沫。宏观变形方面，CoCrFeMnNi 基体良好的断裂韧性使得其泡沫复合材料以一种均匀、分散的韧性方式破坏，变形机制主要为孔棱的塑性弯曲，避免了由裂纹失稳扩展导致的应力跌落和灾变失效。微观组织演化方面，在变形早期阶段，变形机制为位错平面滑移，而在变形后期，试样中出现大量变形孪晶，这些孪晶界阻碍了剪切带的扩展，有效延缓了断裂的发生。通过这些位错滑移和孪 晶，基体得以进行大量的塑性变形，同时具有持续的应变硬化能力。因此，泡沫 具有平稳且宽广的应力平台，进而拥有良好的吸能特性。 （3）研究了CoCrFeMnNi空心微球泡沫在液氮温度下的静动态压缩和吸能性能，并对变形机制和微观组织演化进行了研究。相比于室温，液氮温度下泡沫材料的强度和吸能性能进一步提升，并且没有发生显著的脆化，这和CoCrFeMnNi优异的低温韧性有关。在低温下基体的层错能降低，进一步增加了变形孪晶的活性，同时也促进了剪切带扩展，这些交叉的孪晶和剪切带将基体分割成编织状结构，使得更多原子层在变形中发生错动进而耗散大量能量。同时一些二次孪晶在剪切带内部形成，提供应变硬化。而在动态加载下，则出现了HCP相变，与FCC变形孪晶一起形成纳米层片双相（NLDP）结构，进一步提高了强度和应变硬化能力。 （4）研究了AlCoCrFeNi2.1共晶高熵合金空心微球泡沫在室温下的静动态压缩和吸能性能，发现其同时具有高强度、高吸能总量和高吸能效率，是一种理想的吸能材料。这种良好的强度和吸能性能的结合来自于基体独特的FCC/B2双相共晶结构。较硬的B2相通过载荷分配和产生背应力强化加强了柔软的FCC相；同时，由于两相强度和刚度的不同，在两相间产生应变梯度，随着变形的增加会诱发剪切带的形成，进而造成断裂，提供了多种能量耗散机制。而柔韧的FCC相通过位错滑移、层错、孪晶等塑性变形机制容纳了大量塑性变形并提供应变硬化能力，阻碍了裂纹的形核和扩展，避免了灾难性破坏。这种两相之间的协同作用使应变硬化和剪切带、裂纹带来的软化达到平衡，使得共晶高熵泡沫在高强度的同时具有良好的吸能性能。在动态下，变形更加严重和突然，使得泡沫发生提前致密化，提高了应力水平。此外，在FCC相中发现了大量的交叉层错和L-C锁，提供了额外的应变硬化源。</p

Investigation on specialized care delivered in diabetes outpatient clinic

目的了解糖尿病专科护理门诊现况,为优化流程提供依据。方法采用自制糖尿病专科护理门诊患者满意度问卷对在糖尿病专科护理门诊就诊的200例患者进行调查;对4名糖尿病专科护士进行现场观察与访谈了解工作现况。结果患者满意度总体均分为(4.21±0.49)分,6个维度评分(3.45±0.78)~(4.36±0.64)分;专科门诊护理内容包括健康教育、胰岛素笔使用、检测血糖等13项,每个工作日实施0~48.00次;患者等待就诊时间(14.69±8.00)MIn。专科护理访谈提炼出工作职责不明确、工作时间未建立预约制、门诊导诊护士配合欠佳及患者健康档案登记欠全面4个主题。结论患者对糖尿病专科护理门诊就诊流程和就诊时间等方面满意度较低,专科护士健康教育工作受到影响,应改进流程,以促进健康教育的效果,提高患者满意度。Objective To explore the specialized care delivered in diabetes outpatient clinic,to provide references for further improvement.Methods A total of 200 patients with diabetes were surveyed using a self-developed questionnaire,and 4 diabetes specialist nurses were observed and interviewed about their work.Results The average overall satisfaction score of the patients was(4.21±0.49),with the scores of six dimensions ranging from(3.45±0.78)to(4.36±0.64).The contents of diabetes nursing care in out patient clinic covered 13 items,such as health education,giving guidance about how to use an insulin pen,measuring blood sugar and so on.The frequency of those items conducted ranged from 0 to 48.00 times each day and patient waiting time was(14.69±8.00)min on the average.The interview found 4 problems,including ambiguity of responsibilities of specialty nurses,lack of appointment system,poor cooperation between triage and specialty nurses and incompleteness of the health data about patients.Conclusion Patients′satisfaction levels about waiting time and clinic procedure are low,which impacts the health education implementation.In order to promote patients′satisfaction and improve the health education,better clinic procedures should be explored.厦门市科技局资助科研立项课题(3502Z20124056

保险销售代理坚毅性人格对工作绩效的影响

坚毅是指朝向长期目标的毅力和激情。具备坚毅品格的人一般都具备更多的韧性,而且勤奋。保险销售可能是遭受最多被拒绝的职业,任何一个销售人员,从入职第一天到后来发展成为优秀的销售管理者,一定都有过很多次被拒绝的经历。在这样一个经常需要面对挫折的行业里,具备坚毅品格的保险销售人员会更有利于达到更好的绩效。坚毅除了能对工作绩效产生影响外,也能对保险销售的工作倦怠和心理健康情况产生影响。相关研究表明,个体的坚毅性越高,工作倦怠的感受越小。此外,坚毅性越高,负性生活事件对自杀意图的影响越小。综上,具备坚毅品格的个体更容易在工作中达到更好的绩效,对工作倦怠的感受越小,还能提高心理健康水平。因此,本研究的目的在于对保险企业员工的坚毅情况进行调查,并探讨坚毅对工作绩效的影响机制中,工作倦怠与心理症状充当着什么样的角色。本次研究随机抽取广东省保险销售代理作为被试,约2500名。分别采用CMBI量表、BSI-18量表、GRTI量表对被试的工作倦怠程度、心理症状情况、以及坚毅程度进行采集,而绩效采用上年度标准保费任务、上一年度佣金收入来衡量。首先对回收的问卷进行数据的录入与筛选,删除无效问卷。然后用SPSS进行相关分析。最后用mplus对工作倦怠与心理症状在坚毅与工作绩效之间的作用进行分析后得出以下结论:保险销售代理坚毅性的两个维度,即兴趣稳定性与努力持续性,都与工作绩效呈显著的相关关系。坚毅的兴趣稳定性维度与工作倦怠的成就感降低维度呈显著的负相关关系,与心理症状的抑郁维度呈显著的负相关关系。工作倦怠的情感耗竭和人格解体维度与心理症状的抑郁维度呈显著的正相关关系。工作倦怠的三个维度和心理症状的四个维度都与工作绩效呈负相关关系。而心理症状在工作倦怠与工作绩效之间起着中介作用,工作倦怠在坚毅与工作绩效之间起中介作用。</p

Ultra-high energy absorption high-entropy alloy syntactic foam

Metal matrix syntactic foams (MMSFs) are a class of fascinating particulate composites consisting of metal matrix and hollow spheres, which are promising in the light-weight structural and energy absorbing applications. However, the energy absorption capacity of most MMSFs is suffocated inevitably by relatively low strength of traditional metal matrix alloys, such as widely used aluminum and magnesium alloys. Here, we developed a novel MMSF with CoCrFeMnNi high entropy alloy matrix and alumina cenosphere fillers by pressure infiltration, which exhibits an ultra-high energy absorption capacity of 242.8 +/- 20.6 MJ m(-3), among the highest reported values of MMSFs. We show that this exceptional energy absorption capacity stems from excellent combination of high strength of alumina cenospheres and super-large ductility and fracture toughness of CoCrFeMnNi high entropy alloy. These results shed new light into design of advanced light-weight and energy absorbing materials

Ab initio Calculations of CH Bond Catalytic Activationin CH4 by Oxygen Species on Metal Oxide SurFace

用g94的从头计算方法对甲烷在金属氧化镁及氧化锂表面上不同氧物种O-、O2-2、O-2、O2-催化脱氢进行了理论研究，确定了过渡态的几何构型、集居分布和反应活化能.结果表明，氧物种的催化脱氢的活性顺序为，其中O-2物种由于对甲烷具有较低的氧化能力而可能是OCM活性和高C2选择性的氧物种。另外，还讨论了氧物种对CH4脱氧活性与其电子结构的联系。Ab initio MP2 calculations have been carried out to study C-H bond catalysticactivation in CH4 Various oxygen species O-2 O2-2,O2- are assumed to be the activespecies on the oxide MgO, Li/MgO surFace.Transition states(TS) geometries,MullikenPopulations and reaction activation barriers are determined.The results reveal that the sequencein the activation ability of oxygen species is O2-2 Because the activity of O-2is intermediate between the O- and O2-,O-2 whould be better species in order to oxidativecoupling of methane(OCM) to C2 hydrocarbon with higher choiceness.The relation betweenthe activity of oxygen species For C-H bond activation and their electonic structure isdiscussed.国家自然科学基

煤与瓦斯突出模拟试验装置及其防护装置

本发明公开了一种煤与瓦斯突出模拟试验装置，包括：钢筒，设置在钢筒两端的法兰盘，充气系统和数据采集系统；设置在钢筒一端的法兰盘为带有中心孔的法兰盘，并在该法兰盘与钢筒的非安装侧设置防爆片。本发明还涉及一种煤与瓦斯突出模拟试验装置的防护装置，所述防护装置主要包括一个承接法兰管件和卸压腔、以及防过载安全阀门、放气阀、耐震压力表；承接法兰管件一端与煤与瓦斯突出模拟试验装置连接，另一端通过法兰盘与卸压腔相连，卸压腔的末端设置有法兰盖；所述防护装置可在实验过程中的实时测量及安全泄压

A high-entropy alloy syntactic foam with exceptional cryogenic and dynamic properties

Metal foams are in great demand in extreme service environments with cryogenic temperatures and high strain rates due to their unique properties. However, the reduced ductility and impact toughness under such conditions limit their applications. In this work, we tested the quasi-static and dynamic compression properties of CoCrFeMnNi high entropy alloy syntactic foam at liquid nitrogen temperature (-196 degrees C). We found that it exhibits ultra-high strengths and energy absorption capacity, especially a superior resistance to embrittlement at cryogenic temperature. Microstructural characterizations reveal that the foam matrix has a high twinning activity and shear localization propensity in cryogenic environments. Dense deformation twins and multiple shear bands intersected, forming a weave-like microstructure that can disperse the deformation and benefits energy absorption. Deformation twins can also strengthen the matrix and delay the crack nucleation and growth. While under dynamic loading, an FCC to HCP phase transformation was activated, forming a nano-laminated dualphase (NLDP) FCC/HCP structure in the matrix, leading to further strengthening and toughening. Deformation twinning and HCP phase transformation act as additional plastic deformation mechanisms along with stacking faults and shear bands to offset the shortcomings caused by limited dislocation movements at low temperatures and high strain rate dynamic loading, enabling the high strength and energy absorption of the syntactic foam