Hot deformation of Mg-Y-Zn alloy with a low content of the LPSO phase studied by in-situ synchrotron radiation diffraction

The compressive deformation behavior of the extruded WZ42(Mg98.5Y1Zn0.5 in at.%)magnesium alloy containing a low amount of long-period stacking ordered(LPSO)phase was studied by in-situ synchrotron radiation diffraction technique.Tests were conducted at temperatures between room temperature and 350℃.Detailed microstructure investigation was provided by scanning electron microscopy,particularly the backscattered electron imaging and electron backscatter diffraction technique.The results show that twinning lost its dominance and kinking of the LPSO phase became more pronounced with increasing deformation temperature.No cracks of the LPSO phase and no debonding r at the interface between the LPSO phase and the Mg matrix were observed at temperatures above 200℃.At 350℃,the LPSO phase lost its strengthening effect and the deformation of the alloy was mainly realized by the dynamic recrystallization of the Mg matrix.

Performance of Existing Biased Estimators and the Respective Predictors in a Misspecified Linear Regression Model

In this paper, the performance of existing biased estimators (Ridge Estimator (RE), Almost Unbiased Ridge Estimator (AURE), Liu Estimator (LE), Almost Unbiased Liu Estimator (AULE), Principal Component Regression Estimator (PCRE), r-k class estimator and r-d class estimator) and the respective predictors were considered in a misspecified linear regression model when there exists multicollinearity among explanatory variables. A generalized form was used to compare these estimators and predictors in the mean square error sense. Further, theoretical findings were established using mean square error matrix and scalar mean square error. Finally, a numerical example and a Monte Carlo simulation study were done to illustrate the theoretical findings. The simulation study revealed that LE and RE outperform the other estimators when weak multicollinearity exists, and RE, r-k class and r-d class estimators outperform the other estimators when moderated and high multicollinearity exist for certain values of shrinkage parameters, respectively. The predictors based on the LE and RE are always superior to the other predictors for certain values of shrinkage parameters.

Towards electrochemical hydrogen storage in liquid organic hydrogen carriers via proton-coupled electron transfers

Green hydrogen is identified as one of the prime clean energy carriers due to its high energy density and a zero emission of CO_(2).A possible solution for the transport of H_(2)in a safe and low-cost way is in the form of liquid organic hydrogen carriers(LOHCs).As an alternative to loading LOHC with H_(2)via a two-step procedure involving preliminary electrolytic production of H_(2)and subsequent chemical hydrogenation of the LOHC,we explore here the possibility of electrochemical hydrogen storage(EHS)via conversion of proton of a proton donor into a hydrogen atom involved in covalent bonds with the LOHC(R)via a protoncoupled electron transfer(PCET)reaction:2nH^(+)+2ne^(-)+Rox■n H_(2)^(0)Rred.We chose 9-fluorenone/fluorenol(Fnone/Fnol)conversion as such a model PCET reaction.The electrochemical activation of Fnone via two sequential electron transfers was monitored with in-situ and operando spectroscopies in absence and in presence of different alcohols as proton donors of different reactivity,which enabled us to both quantify and get the mechanistic insight on PCET.The possibility of hydrogen extraction from the loaded carrier molecule was illustrated by chemical activation.

Source of inorganic N affects the cost of growth in a legume tree species(Virgilia divaricata)from the Mediterrean-type Fynbos ecosystem

Aims In Mediterranean-type ecosystem,the Cape Fynbos,legumes may be able to switch between soil N and atmospheric N_(2) sources during growth to adjust the carbon costs of N acquisition.This study investigated the utilization of different inorganic N sources by Virgilia divaricata,a native legume from the Mediterranean-type ecosystem of the Cape Floristic Region.Methods Plants were cultivated in sterile quartz sand,supplied with 25%strength Long Ashton nutrient solution,modified to contain 500μM Phosphate.At the phosphate level(500μM),plants were treated with 500μM NH_(4)NO_(3)(treatment named N),or grown in N-free nutrient solution and inoculated with effective Burkholderia sp.(Bact.)or treated with combined N sources(500μM NH_(4)NO_(3))and inoculated with effective Burkholderia sp.(N+Bact.).Important Findings The application of NH_(4)NO_(3) to the legumes resulted in a greater increase in plant dry matter.Carbon construction costs were higher in plants that were supplied with mineral and symbiotic N sources.Maximum photosynthetic rates per leaf area was maintained,irrespective of the N sources.Although the plant roots were nodulated,the plant dependence on N_(2) fixation decreased with addition of N.Roots and nodules of the plants solely reliant on N_(2) fixation showed an increase in glutamine content.These results show that V.divaricata is highly adapted for growth at the forest margin.Fynbos and possibly anthropic soils by utilizing both atmospheric and soil N sources.

New Membranes Based on Polybenzimidazole for Polymer Fuel Cells

1 Results Acid-doped polybenzimidazoles[1] are particularly appealing because of high proton conductivity with no or low humidification and promising fuel cells performances. PBI, in fact, contains basic functional groups which can easily interact with strong oxo-acids, such as H3PO4 and H2SO4. The acid partially protonates the polymer and partially is freely dispersed in the polymer backbone, so allowing proton migration via Grotthuss mechanism along the anionic chains[2]. Anyway, a technological limit...

刺毛黎豆共生体通过固氮和提高磷吸收来提高植株的生长表现

南非主要以热带稀树草原和草原生态系统为主,这些生态系统具有酸性和营养缺乏的属性,特别是磷和氮素的缺乏。刺毛黎豆(Mucuna pruriens)是在大多数非洲国家广泛存在的一种本土豆科植物,该植物可以抵御这些不利的土壤条件。豆科植物在世界上许多国家具有药用价值,也被用于土壤施肥。尽管已有文献记载了在营养胁迫生态系统中刺毛黎豆的生长和建植,但尚未对其在磷缺乏条件下的共生互作、氮源偏好和与生长相关的碳成本进行研究。在本研究中,我们确定了微生物共生体对磷缺乏条件下的刺毛黎豆氮营养和生长相关的碳成本的影响。我们从4个不同的地理位置采集微生物接种土壤,然后将种子在这些天然土壤中发芽,在根瘤发育的早期,将幼苗转移到无菌石英砂中,并提供不同磷浓度的营养培养基。16S RNA序列结果显示,在不考虑磷浓度的情况下,Burkholderia sp.,Paenibacillus sp.和Bacillus均有分枝。尽管磷缺乏导致总生物量/生长下降,但根系生物量、根瘤数量和碳成本增加。低磷供给的幼树丛枝菌根真菌根系定殖率最高。刺毛黎豆中,大气中的氮与磷水平呈正相关关系,幼树对大气氮素和土壤氮素具有双重依赖,低磷植株对土壤氮素的依赖程度增加。因此,在磷缺乏的情况下,刺毛黎豆表现出不同的形态和微生物共生关系.