Weakly Polarized Organic Cation-Modified Hydrated Vanadium Oxides for High-Energy Efficiency Aqueous Zinc-Ion Batteries

Vanadium oxides,par-ticularly hydrated forms like V_(2)O_(5)·nH_(2)O(VOH),stand out as promising cathode candidates for aqueous zinc ion batteries due to their adjustable layered structure,unique electronic characteristics,and high theoretical capacities.However,challenges such as vanadium dissolution,sluggish Zn^(2+)diffusion kinetics,and low operating voltage still hinder their direct application.In this study,we present a novel vanadium oxide([C_(6)H_(6)N(CH_(3))_(3)]_(1.08)V_(8)O_(20)·0.06H_(2)O,TMPA-VOH),developed by pre-inserting trimethylphenylammonium(TMPA+)cations into VOH.The incorporation of weakly polarized organic cations capitalizes on both ionic pre-intercalation and molecular pre-intercalation effects,resulting in a phase and morphology transition,an expansion of the interlayer distance,extrusion of weakly bonded interlayer water,and a substantial increase in V^(4+)content.These modifications synergistically reduce the electrostatic interactions between Zn^(2+)and the V-O lattice,enhancing structural stability and reaction kinetics during cycling.As a result,TMPA-VOH achieves an elevated open circuit voltage and operation voltage,exhibits a large specific capacity(451 mAh g^(-1)at 0.1 A g^(-1))coupled with high energy efficiency(89%),the significantly-reduced battery polarization,and outstanding rate capability and cycling stability.The concept introduced in this study holds great promise for the development of high-performance oxide-based energy storage materials.

NFT Security Matrix:Towards Modeling NFT Ecosystem Threat

Digital assets have boomed over the past few years with the emergence of Non-fungible Tokens(NFTs).To be specific,the total trading volume of digital assets reached an astounding$55.5 billion in 2022.Nevertheless,numerous security concerns have been raised by the rapid expansion of the NFT ecosystem.NFT holders are exposed to a plethora of scams and traps,putting their digital assets at risk of being lost.However,academic research on NFT security is scarce,and the security issues have aroused rare attention.In this study,the NFT ecological process is comprehensively explored.This process falls into five different stages encompassing the entire lifecycle of NFTs.Subsequently,the security issues regarding the respective stage are elaborated and analyzed in depth.A matrix model is proposed as a novel contribution to the categorization of NFT security issues.Diverse data are collected from social networks,the Ethereum blockchain,and NFT markets to substantiate our claims regarding the severity of security concerns in the NFT ecosystem.From this comprehensive dataset,nine key NFT security issues are identified from the matrix model and then subjected to qualitative and quantitative analysis.This study aims to shed light on the severity of NFT ecosystem security issues.The findings stress the need for increased attention and proactive measures to safeguard the NFT ecosystem.

搅拌摩擦加工制备AZ31/CoCrFeNi复合材料的组织、力学性能和磨损性能

采用搅拌摩擦加工工艺制备CoCrFeNi高熵合金颗粒增强AZ31镁基复合材料。采用OM、SEM、EDS和EBSD对复合材料的微观结构进行表征。通过拉伸、显微硬度和干滑动磨损实验研究复合材料的力学性能和磨损性能。结果表明,高熵合金颗粒分布均匀,与镁基体具有良好的冶金结合。复合材料的屈服强度、抗拉强度和硬度分别比母材高80 MPa、46 MPa和HV 54.9。细晶强化是主要的强化机制,对屈服强度的贡献率为43.9%。复合材料的平均摩擦因数由母材的0.331降低到0.240,磨损机制由母材的黏着磨损转变为磨粒磨损。

20mm厚AZ31镁合金厚板搅拌摩擦焊接接头的显微组织演变及强化机制

采用搅拌摩擦焊焊接20mm厚AZ31镁合金板材,并沿厚度方向分5层对接头的显微组织和力学性能进行表征。结果表明:焊接温度和温降速率的不同导致搅拌区晶粒尺寸不均匀,且在材料流动行为的作用下,接头不同区域形成不同强织构。此外,接头各层的屈服强度和抗拉强度从上表面至下表面整体呈逐渐增加的趋势,伸长率沿接头厚度方向首先由9.5%升高至10.5%,然后逐渐降低至6.0%。整体接头的抗拉强度达到母材的88.5%。接头的主要强化机制为细晶强化。

富含缺陷的Cu@CuTCNQ复合材料增强电催化硝酸盐还原成氨

将硝酸盐(NO_(3))电化学转化为化学原料和燃料氨(NH3),有助于可持续地缓解当前严峻的能源和环境危机.然而,电催化NO_(3)^(-)还原成NH_(3)(NRA)涉及一个缓慢的八电子转移过程,并与水系中的析氢反应(HER)相竞争,这给开发高选择性的NRA催化剂带来巨大挑战.铜基催化剂是最有应用前景的非贵金属催化剂之一,被广泛用于电化学NO_(3)还原研究.然而,块体铜通常表现出较低的NH_(3)选择性且伴随HER竞争反应.近年来,原位表征技术的快速发展使人们能够观察到电解过程中催化剂的结构演变,并验证原位生成的新的高活性相和局部结构(如应变、空位和晶面)在触发高效催化反应中的作用.研究表明,缺陷位点不仅表现出独特的电子特性,而且可以调节相邻原子的电子结构,通过形成新的协同配位结构,来增强化学吸附和改变中间体能垒从而达到最佳性能,已被广泛应用于氧析出、氧还原和二氧化碳还原等电催化反应中.因此,通过结构演化构建富含铜空位缺陷的催化剂,有望提高NRA的活性和选择性.然而,金属表面缺陷工程对电催化反应的影响研究较少,相关反应机理仍不清楚.因此,阐明空位缺陷对NRA的影响和反应机理对于开发高效NRA催化剂具有重要的指导作用.本文通过简单的原位电化学重构方法构建了一种高效的富含铜空位缺陷的铜@四氰基对苯醌二甲烷铜(Cu@CuTCNQ)复合催化剂,用于常温常压NRA反应.X射线衍射精修结果联合X射线吸收光谱表征表明,成功合成了CuTCNQ络合物,其中单分散的金属离子Cu的氧化态为+1价,与N元素配位成键.采用非原位扫描电子显微镜结合原位电化学拉曼光谱研究了NRA过程中CuTCNQ的形貌和结构演变,C-CN拉曼峰发生蓝移表明从CuTCNQ基底到衍生的Cu位点间的电荷转移作用加强.高分辨透射电子显微镜结合电子顺磁共振表征结果表明,衍生的Cu位点表面存在丰富的Cu空位缺陷.丰富的Cu空位缺陷和优化的电荷转移特性使催化剂性能得以提升,在含有0.1 molL^(–1)NO_(3)^(-)的0.1 molL^(–1)KOH溶液中,Cu@CuTCNQ催化剂在-0.6 V vs.RHE还原电位下NRA反应表现出96.4%法拉第效率和144.8μmol h^(–1)cm^(–2)的氨产率,优于结晶性良好的Cu纳米颗粒和大多数Cu基催化剂.利用在线微分电化学质谱对NRA过程的重要中间体NO*和NO_(2)*进行检测,并联合理论计算推测反应途径.结果表明,Cu空位的引入改变了Cu表面的电荷分布,增强了Cu活性位点对NO_(3)^(-)的吸附,降低了电势决速步反应能垒,从而使得NRA的脱氧和加氢过程在热力学上更有利.同时,富含Cu空位缺陷的表面有利于抑制析氢竞争反应,二者共同增强了NRA的活性和选择性.综上,本文突出了通过原位电化学重构策略构建高效NRA催化剂的重要性,并提供了对金属空位-活性依赖性关系的基本理解.

葛根素通过抑制MAPK/NF-κB信号通路调节LPS诱导的人牙髓干细胞的炎症损伤和成骨分化

目的:探讨葛根素(PR)对炎症条件下人牙髓干细胞(hDPSCs)成骨分化的影响及机制。方法:分离培养hDPSCs,CCK-8法检测PR对hDPSCs增殖活力的影响。将hDPSCs分为对照组、脂多糖(LPS)组、p38 MAPK抑制剂SB203580组(20μmol/L)、20μmol/L PR组、40μmol/L PR组、40μmol/L PR+20μmol/L SB203580组,采用LPS诱导建立体外hDPSCs炎症模型。通过乳酸脱氢酶(LDH)测定法、茜素红染色和碱性磷酸酶(ALP)活性测定评估PR对LPS诱导的hDPSCs细胞毒性和成骨分化能力的影响,实时荧光定量PCR(RT-qPCR)检测细胞中炎症(IL-6、IL-1β、TNF-α)和成骨分化相关基因(RUNX2、OCN、BSP)表达,Western blot检测细胞中丝裂原活化蛋白激酶(MAPK)/核因子-κB(NF-κB)通路相关蛋白表达。结果:20和40μmol/L的PR可显著增加hDPSCs的增殖活力,增强LPS刺激的hDPSCs中ALP活性、矿化结节和成骨分化相关基因的表达,降低LDH活性和炎症相关基因表达,抑制IκBα的磷酸化降解和NF-κB p65、p38 MAPK的磷酸化(均P<0.05)。40μmol/L PR与SB203580对MAPK信号通路的抑制作用接近,两者联用对MAPK/NF-κB信号通路的抑制作用和炎症状态下hDPSCs成骨分化的促进作用明显优于两者单独应用。结论:PR可减轻LPS诱导的hDPSCs炎症损伤,促进炎症状态下hDPSCs成骨分化;其作用机制可能与抑制MAPK/NF-κB信号通路有关。

An Al–Al interpenetrating-phase composite by 3D printing and hot extrusion

We report a process route to fabricate an Al–Al interpenetrating-phase composite by combining the Al–Mg–Mn–Sc–Zr lattice structure and Al_(84)Ni_(7)Gd_(6)Co_(3)nanostructured structure. The lattice structure was produced by the selective laser melting and subsequently filled with the Al_(84)Ni_(7)Gd_(6)Co_(3)amorphous powder, and finally the mixture was used for hot extrusion to produce bulk samples. The results show that the composites achieve a high densification and good interface bonding due to the element diffusion and plastic deformation during hot extrusion.The bulk samples show a heterogeneous structure with a combination of honeycomb lattice structure with an average grain size of less than1 μm and nanostructured area with a high volume fraction of nanometric intermetallics and nanograin α-Al. The heterogeneous structure leads to a bimodal mechanical zone with hard area and soft area giving rise to high strength and acceptable plasticity, where the compressive yield strength and the compressive plasticity can reach ~745 MPa and ~30%, respectively. The high strength can be explained by the rule of mixture,the grain boundary strengthening, and the back stress, while the acceptable plasticity is mainly owing to the confinement effect of the nanostructured area retarding the brittle fracture behavior.

冷喷摩擦复合增材制造6061铝合金的显微组织、力学性能和腐蚀行为

采用冷喷摩擦复合增材制造(CFAM)技术制备6061铝合金块体材料。采用OM、SEM和EBSD对冷喷涂(CS)和CFAM试样的显微组织进行表征,通过显微硬度、拉伸和腐蚀实验研究两者的力学性能和腐蚀行为。结果表明,与CS试样相比,CFAM试样的显微组织更加致密和均匀,晶粒细小等轴,平均晶粒尺寸为3.1μm,显微硬度、极限抗拉强度和伸长率分别提高了22%、171%和683%。CFAM试样的腐蚀电流密度比CS试样低95.1%~97.8%,腐蚀机理由CS试样的点腐蚀转变为晶间腐蚀。

Magnetic Field-Based Reward Shaping for Goal-Conditioned Reinforcement Learning

Goal-conditioned reinforcement learning(RL)is an interesting extension of the traditional RL framework,where the dynamic environment and reward sparsity can cause conventional learning algorithms to fail.Reward shaping is a practical approach to improving sample efficiency by embedding human domain knowledge into the learning process.Existing reward shaping methods for goal-conditioned RL are typically built on distance metrics with a linear and isotropic distribution,which may fail to provide sufficient information about the ever-changing environment with high complexity.This paper proposes a novel magnetic field-based reward shaping(MFRS)method for goal-conditioned RL tasks with dynamic target and obstacles.Inspired by the physical properties of magnets,we consider the target and obstacles as permanent magnets and establish the reward function according to the intensity values of the magnetic field generated by these magnets.The nonlinear and anisotropic distribution of the magnetic field intensity can provide more accessible and conducive information about the optimization landscape,thus introducing a more sophisticated magnetic reward compared to the distance-based setting.Further,we transform our magnetic reward to the form of potential-based reward shaping by learning a secondary potential function concurrently to ensure the optimal policy invariance of our method.Experiments results in both simulated and real-world robotic manipulation tasks demonstrate that MFRS outperforms relevant existing methods and effectively improves the sample efficiency of RL algorithms in goal-conditioned tasks with various dynamics of the target and obstacles.

Effect of addition of minor amounts of Sb and Gd on hot tearing susceptibility of Mg-5Al-3Ca alloy

The effects of addition of minor amount of(0.5 wt.%) antimony(Sb) or gadolinium(Gd) and combined addition of Sb and Gd(0.5 wt.%,respectively) on the hot tearing susceptibility(HTS) of Mg-5Al-3Ca alloy were investigated experimentally using a “T-shaped” hot tearing measuring system. Various solidification parameters of the alloys were measured and calculated through thermal analysis experiments. The microstructure, grain size, and morphology of the crack zone were characterized by scanning electron microscopy and electron backscatter diffraction, and the crystal phases of the alloys were analyzed by X-ray diffraction and energy-dispersive X-ray spectroscopy. The results showed that the addition of 0.5 wt.% Gd resulted in the increase in the vulnerable temperature range(Tv) and reduced the eutectic structure content that could participate in feeding, thereby improving the HTS of the alloy. However, addition of 0.5 wt.% Sb or combined addition of Gd and Sb(0.5 wt.%, respectively) to the Mg-5Al-3Ca alloy shortened the Tvand improved the skeleton strength of the alloy, thereby reducing HTS. Moreover, significantly refined structure of Mg-5Al-3Ca-0.5Gd-0.5Sb alloy improved the feeding ability of the eutectic structure, thus the alloy exhibited the lowest HTS.

Short-Term Mindfulness Intervention on Adolescents’ Negative Emotion under Global Pandemic

Objective:In this research,we tried to explore how short-term mindfulness(STM)intervention affects adoles-cents’anxiety,depression,and negative and positive emotion during the COVID-19 pandemic.Design:10 classes were divided into experiment groups(5 classes;n=238)and control(5 classes;n=244)randomly.Hospital Anxi-ety and Depression Scale(HADS)and Positive and Negative Affect Schedule(PANAS)were used to measure par-ticipants’dependent variables.In the experiment group,we conducted STM practice interventions every morning in theirfirst class from March to November 2020.No interventions were conducted in the control group.Methods:Paired-sample t-tests were used to identify if a significant difference exists between every time point of the experimental and control groups.Repeated ANOVA and Growth Mixture Model(GMM)were used to analyze the tendency of positive and negative emotions,anxiety,and depression in the experimental group.Results and Conclusions:(1)With the intervention of STM,there was a significant decrease in negative emotions and an increase in positive emotions in the experimental group,whereas there were non-significant differences in the control group.(2)To explore the heterogeneity trajectories of dependent variables,we built a GMM and found there were two latent growth classes in the trajectories.(3)The results of the models showed their trajec-tories were downward,which meant that the levels of anxiety,depression,and negative emotions of participants decreased during the STM training period.Nonetheless,the score of positive affect showed upward in three loops of intervention,which indicated that the level of the participants’positive affect increased through the STM inter-vention.(4)This research indicated that STM should be given increasing consideration to enhance mental health during the worldwide outbreak of COVID-19.

Exosomes from circ-Astn1-modified adipose-derived mesenchymal stem cells enhance wound healing through miR-138-5p/SIRT1/FOXO1 axis regulation

BACKGROUND Wound healing impairment is a dysfunction induced by hyperglycemia and its effect on endothelial precursor cells(EPCs)in type 2 diabetes mellitus.There is increasing evidence showing that exosomes(Exos)derived from adipose-derived mesenchymal stem cells(ADSCs)exhibit the potential to improve endothelial cell function along with wound healing.However,the potential therapeutic mechanism by which ADSC Exos contribute to wound healing in diabetic mice remains unclear.AIM To reveal the potential therapeutic mechanism of ADSC Exos in wound healing in diabetic mice.METHODS Exos from ADSCs and fibroblasts were used for high-throughput RNA sequencing(RNA-Seq).ADSC-Exo-mediated healing of full-thickness skin wounds in a diabetic mouse model was investigated.We employed EPCs to investigate the therapeutic function of Exos in cell damage and dysfunction caused by high glucose(HG).We utilized a luciferase reporter(LR)assay to analyze interactions among circular RNA astrotactin 1(circ-Astn1),sirtuin(SIRT)and miR-138-5p.A diabetic mouse model was used to verify the therapeutic effect of circ-Astn1 on Exo-mediated wound healing.RESULTS High-throughput RNA-Seq analysis showed that circ-Astn1 expression was increased in ADSC Exos compared with Exos from fibroblasts.Exos containing high concentrations of circ-Astn1 had enhanced therapeutic effects in restoring EPC function under HG conditions by promoting SIRT1 expression.Circ-Astn1 expression enhanced SIRT1 expression through miR-138-5p adsorption,which was validated by the LR assay along with bioinformatics analyses.Exos containing high concentrations of circ-Astn1 had better therapeutic effects on wound healing in vivo compared to wild-type ADSC Exos.Immunofluorescence and immunohistochemical investigations suggested that circ-Astn1 enhanced angiopoiesis through Exo treatment of wounded skin as well as by suppressing apoptosis through promotion of SIRT1 and decreased forkhead box O1 expression.CONCLUSION Circ-Astn1 promotes the therapeutic effect of ADSC-Exos and thus improves wound healing in diabetes via miR-138-5p absorption and SIRT1 upregulation.Based on our data,we advocate targeting the circ-Astn1/miR-138-5p/SIRT1 axis as a potential therapeutic option for the treatment of diabetic ulcers.

Traceability Technology of DC Electric Energy Metering for On-Site Inspection of Chargers

The on-site inspection of high-power DC chargers results in new DC high-current measurement and DC energy traceability system requirements.This paper studies the traceability technology of electric energy value for automotive high-power DC chargers,including:(1)the traceability method of the built-in DC energy meter and shunt of the charger;(2)precision DC high current and small precision DC voltage output and measurement technology.This paper designs a 0.1 mA∼600 A DC high current measurement system and proposes a 0.005 level DC powermeasurement traceability system.The uncertainty evaluation experiment of theDC powermeasurement calibration system and the high-power DC charger’s on-site calibration experiment results verify the method’s effectiveness and feasibility in this paper.The experimental results show that the combined standard uncertainty of the DC power metering verification system can be 0.0451%.

Ethnobotany and diversity of medicinal plants used by the Buyi in eastern Yunnan, China

The Buyi are a socio-linguistic group in Yunnan Province of southwest China that have a long history of using medicinal plants as part of their indigenous medical system.Given the limited written documentation of the Buyi indigenous medical system,the objective of this paper is to document the medicinal plants of the Buyi and associated traditional knowledge and transmission.Field research was conducted in four villages in Lubuge Township of Luoping County in Yunnan Province using ethnobotanical methodologies including participatory observation,semi-structured interviews,key informant interviews,and focus group discussions to elicit information on medicinal plants.In total,120 informants(including 15 key informants who are healers)were interviewed.This study found that a total of 121 medicinal plant species belonging to 64 families are used by the Buyi including by local healers to treat different diseases.Among the medicinal plants recorded in this study,56 species(46%)have not previously been documented in the scientific literature as having medicinal value,highlighting the pressing need for ethnobotanical documentation in indigenous communities.The most frequently used medicinal part was the leaf(24.9%of documented plants),and the most common preparation method was decoction(62.8%of medicinal).Medicinal plants were mainly used to treat rheumatism(12.4%of plants),trauma and injuries(9.6%).The documented plants are also used for other non-medicinal purposes including food,fodder,fencing,and ornamental.In addition,35 of the medicinal plants are considered poisonous and are used by local Buyi healers for medicine.The traditional Buyi beliefs and practices associated with the documented medicinal plants likely contributes to their conservation in the environments and around Buyi communities.This study further highlights that ethnomedicinal knowledge of the Buyi is at risk of disappearing due to increased introduction and use of modern medicine in Buyi communities,livelihood changes,rapid modernization,and urbanization.Research,policy,and community programs are urgently needed to conserve the biocultural diversity associated with the Buyi medical system including ethnobotanical knowledge towards supporting both environmental and human wellbeing.

Si和Ti对高性能Cu-15Ni-8Sn合金在热变形过程中动态再结晶的作用（英文）

采用不同变形条件(变形温度750~950℃、应变速率0.001~10 s^-1)的热压缩试验研究微量元素Si和Ti添加对Cu-15Ni-8Sn合金动态再结晶的作用。结果表明,添加Si和Ti对热变形过程中的动态再结晶具有显著的作用。添加的Si和Ti可以形成Ni16Si7Ti6相,Ni16Si7Ti6相促进低角度晶界向高角度晶界转变,因此,促进动态再结晶的形核过程;同时,Ni16Si7Ti6相产生的钉扎作用抑制再结晶晶粒的长大。基于动态再结晶行为建立热加工图以优化合金的热变形工艺参数。在最优工艺参数下制备具有细小晶粒组织的热挤压态Cu-15Ni-8Sn合金,其伸长率达到30%,抗拉强度达到910 MPa。

关节镜清理术联合艾瑞昔布对膝骨性关节炎的疗效及对MMP-2、MMP-13水平的影响

目的分析关节镜清理治疗膝骨性关节炎(KOA)术后联合艾瑞昔布的疗效及对基质金属蛋白酶2(MMP-2)、基质金属蛋白酶13(MMP-13)水平的影响。方法选取2014年12月-2016年12月遵义市第一人民医院收治的65例KOA患者,根据术后用药不同将其分为对照组和观察组。两组均采用关节镜下有限清理术治疗;对照组术后服用安慰剂治疗,观察组术后服用艾瑞昔布治疗。观察两组治疗前后关节功能改善情况、生活质量评分情况、关节液中MMP-2、MMP-13、基质金属蛋白酶抑制剂1(TIMP-1)水平和血清中一氧化氮(NO)、白细胞介素1β(IL-1β)及白细胞介素1(IL-1)水平变化情况。结果两组治疗后疼痛评分、日常活动评分、关节僵硬评分及综合评分均较治疗前下降,观察组治疗后疼痛评分、日常活动评分、关节僵硬评分及综合评分均低于对照组(P<0.05);两组治疗后关节液中MMP-2、MMP-13及TIMP-1水平均较治疗前下降,观察组治疗后关节液中MMP-2、MMP-13及TIMP-1水平均低于对照组(P<0.05)。两组治疗后血清NO和IL-1水平均较治疗前下降,而IL-1β水平较治疗前上升(P<0.05);观察组治疗后血清NO和IL-1水平均低于对照组,而IL-1β水平高于对照组(P<0.05);两组治疗后生活质量评分较治疗前改善,观察组治疗后生活质量评分优于对照组(P<0.05)。结论关节镜清理术后联合艾瑞昔布治疗KOA可有效改善患者关节功能,降低患者关节液中MMP-2、MMP-13水平,提高患者生活质量。

Mg-7Zn-xCu-0.6Zr合金的热裂行为及热分析测试（英文）

通过热分析方法研究Mg-7Zn-x Cu-0.6Zr合金在凝固过程中的显微组织演变。采用具有测力传感器和数据采集系统的约束棒实验装置研究Cu含量(0,1,2和3,质量分数,%)对Mg-7Zn-x Cu-0.6Zr合金热裂行为的影响。Mg-7Zn-xC u-0.6Zr合金的热分析结果表明,该合金主要由α-Mg和Mg Zn2相组成,而含Cu合金有3个潜热释放峰,分别对应α-Mg、Mg Zn Cu和Mg Zn2相。同时,随着Cu含量的增加,α-Mg相的反应温度降低,Mg Zn2和MgZ n Cu相的反应温度升高。热裂实验结果表明,由于添加Cu能提高合金的共晶温度,而缩小凝固温度区间,因此,Mg-7Zn-x Cu-0.6Zr合金的热裂敏感性明显降低。

Mg-xZn-2Y合金的热裂敏感倾向性（英文）

采用具有测力传感器和数据采集系统的约束棒实验装置研究Zn含量(0,0.5%,1.5%和4.5%)对Mg-2%Y合金热裂敏感倾向性的影响。实验结果表明,不添加Zn元素的合金热裂敏感倾向性最小。随着Zn含量的增加,Mg-2%Y合金的热裂敏感倾向性增强,当Zn含量为1.5%时达到最大值,然后随着Zn含量的进一步增加热裂敏感倾向性降低。在凝固过程中,由于Mg-1.5Zn-2Y合金具有较大的收缩力下降和凝固收缩力释放率,导致该合金的热裂敏感倾向最大。Mg-xZn-2Y系合金的热裂纹是沿着枝晶或晶界萌生和扩展的。通过ProCAST软件模拟合金的热裂敏感倾向性与实验结果一致。

稀有植物山东银莲花(Anemone shikokiana (Makino) Makino)的核型分析及其生境对染色体变异的影响

山东银莲花(Anemone shikokiana)分布极其狭域,典型的稀有物种,具有很高的研究价值。主要分布于含有大量腐殖土的针阔混交林下和含砂壤土的干旱山顶灌丛。植物的核型对其后续研究至关重要,本研究采用常规压片法和Levan的核型分析方法,首次研究了山东银莲花的染色体数目及核型,结果表明:体细胞中期染色体数目为14,核型公式为2n = 2X = 14 = 12m + 2t,核型为“2A”型,核型不对称系数(A.S.K%)为56.5%,染色体相对长度组成为2n = 2X = 14 = 12L +2M1。为了探索生境对染色体的影响,对染色体的性状进行了巢式方差分析,发现不同生境的居群间染色体形态和大小变异不显著,居群内染色体的形态和大小存在一定程度的变异,表明山东银莲花染色体的变异存在于小尺度范围内,大尺度范围的变异可能由于足够大的群体足够多的个体而导致染色体水平的相互抵消。本研究为今后进一步研究打下一定的基础。

电弧喷涂快速模具的3Cr13涂层工艺参数优化

为了确定电弧喷涂快速模具型壳材料3Cr13的喷涂工艺参数,用正交试验法研究了喷涂工艺参数对涂层厚度、涂层硬度和孔隙率的影响,并利用光学和电子显微镜对喷涂涂层的微观形貌进行了观察和分析。结果表明:所获得的喷涂工艺参数,较好的实现了喷涂模具的制造及应用,可用于汽车覆盖件的冲压制造。