Understanding the electrochemical properties of Mg-doped Li2MnO3: first-principles calculations.

Non-transition metal doping, especially for Mg, has been gradually employed to optimize the electrochemical performance of Li-rich cathode material Li2MnO3. However, the effects of Mg doping on the electrochemical behavior of Li2MnO3 have not been studied extensively. In this work, we investigate the effect of Mg doping at both the 2b (in the Li/Mn mixed layer) and 4h (in the Li layer) Li sites on the electrochemical properties of Li2MnO3 through first-principles calculations and ab initio molecular dynamics simulations. The local lattice structure, electronic density of states, Bader charge, delithiation voltage, lattice oxygen stability and Li diffusion kinetics are examined. Electronic structure analysis shows that Mg can activate the electrochemical activity of surrounding Mn by charge transfer, making Mn participate in charge compensation at the initial delithiation stage. Mg doping can also cause an increase in the average oxygen vacancy formation energy and hence depress the oxygen release during the delithiation process. Molecular dynamics simulations show that the diffusion kinetics of Li ions in Mg2b-Li2MnO3 is enhanced with respect to the undoped one, whereas Mg doped at the 4h site cannot improve the diffusion kinetics of Li ions. Further studies found that Mg doped at the 2b site results in a decrease in the energy barrier for the intra-layer diffusion and an increase in the energy barrier for the inter-layer diffusion of the nearby Li vacancies.

Cationic Oxidative Leaching Engineering Modulated In Situ Self-Reconstruction of Nickel Sulfide for Superior Water Oxidation.

Tuning the electroactive surface species of electrocatalysts remains a significant challenge for achieving highly efficient oxygen evolution reactions. Herein, we propose an innovative in situ leaching strategy, modulated by cationic oxidation, to achieve active self-reconstruction of these catalysts. Vanadium is introduced as a cation into Ni3S2 and oxidized under low oxidative potential, leading to subsequent leaching into the electrolyte and triggering self-reconstruction. The structural evolution from V-Ni3S2 to Ni(OH)2 and subsequently to NiOOH is identified by operando Raman as a three-step transition. In contrast, V-free Ni3S2 is unable to bypass the thermodynamically predicted nickel oxysulfide products to transform into active NiOOH. As a result, the self-restructured V-Ni3S2 only needs an ultralow overpotential of 155 mV at 10 mA cm-2, outperforming V-free Ni3S2 and many other advanced catalysts. This work provides new guidelines for manipulating in situ leaching to modulate the self-reconstruction of catalysts.

Design and Construction of Carbon-Coated Fe3 O4 /Cr2 O3 Heterostructures Nanoparticles as High-Performance Anodes for Lithium Storage.

Transition metal oxides, highly motivated anodes for lithium-ion batteries due to high theoretical capacity, typically afflict by inferior conductivity and significant volume variation. Architecting heterogeneous structures with distinctive interfacial features can effectively regulate the electronic structure to favor electrochemical properties. Herein, an engineered carbon-coated nanosized Fe3 O4 /Cr2 O3 heterostructure with multiple interfaces is synthesized by a facile sol-gel method and subsequent heat treatment. Such ingenious components and structural design deliver rapid Li+ migration and facilitate charge transfer at the heterogeneous interface. Simultaneously, the strong coupling synergistic interactions between Fe3 O4 , Cr2 O3 , and carbon layers establish multiple interface structures and built-in electric fields, which accelerate ion/electron transport and effectively eliminate volume expansion. As a result, the multi-interface heterostructure, as a lithium-ion battery anode, exhibits superior cycling stability maintaining a reversible capacity of 651.2 mAh g-1 for 600 cycles at 2 C. The density functionaltheory calculations not only unravel the electronic structure of the modulation but also illustrate favorable lithium-ion adsorption kinetics. This multi-interface heterostructure strategy offers a pathway for the development of advanced alkali metal-ion batteries.

Understanding the different effects of 4d-transition metals on the performance of Li-rich cathode Li2MnO3 by first-principles.

The poor cycling performance of Li-rich cathode Li2MnO3, a promising cathode for next-generation Li-ion batteries, limits its commercial applications. Transition metal (TM) doping is widely applied to optimize the electrochemical performance of Li2MnO3, where the d valence electrons of the TM play a crucial role. Nevertheless, the rule of the doping effect of TM with various numbers of d electrons has not been well summarized. In this work, 4d-TMs (Zr, Nb, Mo, Ru and Rh) are selected as dilute doping elements for Li2MnO3 to evaluate their effect on the performance of Li2MnO3 through first-principles calculations. The calculations indicate that as the number of 4d electrons increases, the doped TM transforms from an electrochemically inert state (Zr and Nb) to an electrochemically active state (Mo, Ru and Rh) in Li2MnO3. Meanwhile, the orbital hybridization between the 4d electrons of the TM and the 2p electrons of O becomes stronger from Zr to Rh, which promotes the co-oxidation of the TM and O for charge compensation and alleviates the excessive oxidation of O, thus enhancing the stability of O. Moreover, the oxidation of the doped TM and lattice Mn during charging can trigger a decrease in the initial average delithiation potential. Although the 4d-TMs exhibit slight promoting or inhibiting effects on Li diffusion, no obvious rule related to the number of d electrons has been found. Our work highlights the rule of the doping effect of TMs with different 4d electrons on the electrochemical performance of Li2MnO3 and would facilitate a better design of Li2MnO3 cathode materials.

Heterogeneous Atoms Substituted Rock Salt Phase Mn1 -x Fex O Solid Solution with Rich Defects for Advanced Lithium-Ion Batteries.

Heterogeneous atoms substitution is an efficient method for promoting Li+ storage of transition metal oxides. Herein, a series of Fe-substituted MnO solid solutions with different Fe contents are synthesized by a feasible solid-phase method. The synergistic effects between heterogeneous atoms and rich vacancies are synchronously obtained, which hold distinctive electronic structures and substantial active sites. When optimized Mn0.55 Fe0.45 O solid solution as anodes for lithium-ion batteries, pre-prepared electrodes exhibit reversible lithium storage of 1286.9 mAh g-1 at 1 A g -1 after 400 cycles and even 628.1 mAh g-1 at 2 A g-1 after 1000 cycles. The LiCoO2 //Mn0.55 Fe0.45 O full cells are assembled, achieving the reversible capacity of 130.2 and 111.3 mAh g-1 after 150 cycles at 0.1 and 0.2 A g-1 , respectively. Density functional theory calculations also authenticate that the electrochemical activity can be markedly boosted by the heterogeneous atoms substituted Mn1 -x Fex O solid solution.

Ultrathin and Super Strong UHMWPE Supported Composite Anion Exchange Membranes with Outstanding Fuel Cells Performance.

For high-performance anion exchange membrane fuel cells (AEMFCs), the anion exchange membrane (AEMs) should be as thin as possible to reduce the ohmic resistance. However, the mechanical stability of ultrathin AEMs cannot be guaranteed, as well as a huge risk of gas (H2 &O2 ) permeation. In this work, composite AEMs based on ultrahigh molecular weight polyethylene (UHMWPE) are prepared by in situ bulk polymerization. The as-prepared composite membranes can be as thin as 4 µm, and possess super high strength beyond 150 MPa. It also shows extremely low hydrogen permeation, low water uptake, low dimensional swelling, high conductivity, and good alkaline stability. In addition, the fuel cell performance based on the ultrathin composite AEMs exhibits outstanding peak power density of 1014 and 534 mW cm-2 for H2 -O2 and H2 -Air (CO2 -free) at 65 °C, respectively, as well as good short-term durability.

Ab initio molecular dynamics study on the disordered Li-Ga-Sn system.

The eutectic Ga91.6Sn8.4 liquid metal could serve as the anode in Li-ion batteries to avoid dendrite growth issue and volume expansion, and maintain a good cycle life. However, the microstructure and the basic physical properties of the lithiated Ga91.6Sn8.4 are ignored in experiments and still unclear. In this work, we assume that a disordered structure is formed in the initial stage of lithiation of Ga91.6Sn8.4, and the structure, equilibrium density, thermal expansion coefficient, mixing enthalpy, self-diffusion coefficient and viscosity of the disordered Li-Ga-Sn system are investigated systematically by ab initio molecular dynamics. The radial distribution function, structure factor and bond angle distribution function are calculated to obtain local structure information. Our calculations show that the lithiation of Ga91.6Sn8.4 is exothermic, and for most cases, the diffusion coefficients for Li, Ga and Sn decrease with increasing Li content. Based on structural information and diffusion coefficients, we reveal that the lithiation of Ga91.6Sn8.4 will make the liquid Ga91.6Sn8.4 alloy form a solid-like structure. With the increase of Li content, it is more likely to form a solid-like structure. Furthermore, our simulations reveal that the chemical interaction of Li-Sn and Li-Ga is stronger than that of Ga-Sn, and Li is prone to combine with Sn firstly in the lithiation process of Ga91.6Sn8.4.

Distinct recognition of complement iC3b by integrins αXß2 and αMß2.

Recognition by the leukocyte integrins αXß2 and αMß2 of complement iC3b-opsonized targets is essential for effector functions including phagocytosis. The integrin-binding sites on iC3b remain incompletely characterized. Here, we describe negative-stain electron microscopy and biochemical studies of αXß2 and αMß2 in complex with iC3b. Despite high homology, the two integrins bind iC3b at multiple distinct sites. αXß2 uses the αX αI domain to bind iC3b on its C3c moiety at one of two sites: a major site at the interface between macroglobulin (MG) 3 and MG4 domains, and a less frequently used site near the C345C domain. In contrast, αMß2 uses its αI domain to bind iC3b at the thioester domain and simultaneously interacts through a region near the αM ß-propeller and ß2 ßI domain with a region of the C3c moiety near the C345C domain. Remarkably, there is no overlap between the primary binding site of αXß2 and the binding site of αMß2 on iC3b. Distinctive binding sites on iC3b by integrins αXß2 and αMß2 may be biologically beneficial for leukocytes to more efficiently capture opsonized pathogens and to avoid subversion by pathogen factors.

Atypical interactions of integrin αVß8 with pro-TGF-ß1.

Integrins αVß6 and αVß8 are specialized for recognizing pro-TGF-ß and activating its growth factor by releasing it from the latency imposed by its surrounding prodomain. The integrin αVß8 is atypical among integrins in lacking sites in its cytoplasmic domain for binding to actin cytoskeleton adaptors. Here, we examine αVß8 for atypical binding to pro-TGF-ß1. In contrast to αVß6, αVß8 has a constitutive extended-closed conformation, and binding to pro-TGF-ß1 does not stabilize the open conformation of its headpiece. Although Mn2+ potently activates other integrins and increases affinity of αVß6 for pro-TGF-ß1 25- to 55-fold, it increases αVß8 affinity only 2- to 3-fold. This minimal effect correlates with the inability of Mn2+ and pro-TGF-ß1 to stabilize the open conformation of the αVß8 headpiece. Moreover, αVß8 was inhibited by high concentrations of Mn2+ and was stimulated and inhibited at markedly different Ca2+ concentrations than αVß6 These unusual characteristics are likely to be important in the still incompletely understood physiologic mechanisms that regulate αVß8 binding to and activation of pro-TGF-ß.

Ligand- and cation-induced structural alterations of the leukocyte integrin LFA-1.

In αI integrins, including leukocyte function-associated antigen 1 (LFA-1), ligand-binding function is delegated to the αI domain, requiring extra steps in the relay of signals that activate ligand binding and coordinate it with cytoplasmic signals. Crystal structures reveal great variation in orientation between the αI domain and the remainder of the integrin head. Here, we investigated the mechanisms involved in signal relay to the αI domain, including whether binding of the ligand intercellular adhesion molecule-1 (ICAM-1) to the αI domain is linked to headpiece opening and engenders a preferred αI domain orientation. Using small-angle X-ray scattering and negative-stain EM, we define structures of ICAM-1, LFA-1, and their complex, and the effect of activation by Mn2+ Headpiece opening was substantially stabilized by substitution of Mg2+ with Mn2+ and became complete upon ICAM-1 addition. These agents stabilized αI-headpiece orientation, resulting in a well-defined orientation of ICAM-1 such that its tandem Ig-like domains pointed in the opposite direction from the ß-subunit leg of LFA-1. Mutations in the integrin ßI domain α1/α1' helix stabilizing either the open or the closed ßI-domain conformation indicated that α1/α1' helix movements are linked to ICAM-1 binding by the αI domain and to the extended-open conformation of the ectodomain. The LFA-1-ICAM-1 orientation described here with ICAM-1 pointing anti-parallel to the LFA-1 ß-subunit leg is the same orientation that would be stabilized by tensile force transmitted between the ligand and the actin cytoskeleton and is consistent with the cytoskeletal force model of integrin activation.

Relationship Between IL-10 Gene Polymorphism and Spinal Tuberculosis.

BACKGROUND To investigate the relation between interleukin-10 (IL-10) gene rs1800871 (A/G) polymorphism and spinal tuberculosis. MATERIAL AND METHODS A total of 129 patients with spinal tuberculosis (spinal tuberculosis group) and 106 healthy subjects receiving physical examination (control group) were enrolled in this study. The general data of these subjects were collected, and the C-reactive protein, erythrocyte sedimentation rate (ESR) and baseline hematologic function were examined. The rs1800871 (A/G) polymorphism in IL-10 gene was detected by TaqMan-MGB probe method. RESULTS The C-reactive protein, ESR, white blood cell count, absolute neutrophil count and relative neutrophil count in spinal tuberculosis group were higher than those in control group, while the absolute lymphocyte count and relative lymphocyte count were lower than those in control group (p<0.05). Compared with AA genotype, GG and AG+GG genotypes showed statistically significant difference in distribution frequency (p<0.05), but no significant difference was detected between AG genotype and AA genotype (p>0.05). In spinal tuberculosis group, the frequency of G allele was higher than that of A allele (p<0.01). The C-reactive protein, ESR, white blood cell count and relative neutrophil count in GG genotype were increased compared with those in AG+GG genotype (p<0.05). CONCLUSIONS The rs1800871 (A/G) polymorphism in IL-10 gene is related to the susceptibility to spinal tuberculosis. Moreover, carrying G allele increases the risk of spinal tuberculosis.

Construction of Soft Base Tongs on Separator to Grasp Polysulfides from Shuttling in Lithium-Sulfur Batteries.

Rechargeable lithium-sulfur batteries, which use sulfur as the cathode material, promise great potentials to be the next-generation high-energy system. However, higher-order lithium polysulfides, Li2 Sx (x = 4, 6, and 8), regardless of in charge or in discharge, always form first, dissolve subsequently in the electrolyte, and shuttle to the cathode and the anode, which is called "shuttle effect." The polysulfides shuttle effect leads to heavy loss of the active-sulfur materials. Literature works mostly "cover or fill" the pores to block polysulfides from shuttling, which also hinder the lithium ion transfer. Here a protocol is invented to grasp polysulfides based on the "soft and hard acid-base" theory. Tertiary amine layer (TAL) polymerized on a polypropylene separator selectively coordinates with the dissolved high-order Li2 Sx in the cathode. Meanwhile, the transportation of lithium cations is not interrupted because of enough pores left for their transportation. After 400 cycles of charge/discharge at 0.5C, the TAL modified separator battery still possesses a capacity of 865 mAh g-1 , which is among the best of the state-of-the-art performances of lithium-sulfur batteries. The flexible "polysulfides tongs" construction method paves a new way for Li-S batteries to reach desired performances with less worry about polysulfides shuttle.

Structural basis of intramitochondrial phosphatidic acid transport mediated by Ups1-Mdm35 complex.

Ups1 forms a complex with Mdm35 and is critical for the transport of phosphatidic acid (PA) from the mitochondrial outer membrane to the inner membrane. We report the crystal structure of the Ups1-Mdm35-PA complex and the functional characterization of Ups1-Mdm35 in PA binding and transfer. Ups1 features a barrel-like structure consisting of an antiparallel ß-sheet and three α-helices. Mdm35 adopts a three-helical clamp-like structure to wrap around Ups1 to form a stable complex. The ß-sheet and α-helices of Ups1 form a long tunnel-like pocket to accommodate the substrate PA, and a short helix α2 acts as a lid to cover the pocket. The hydrophobic residues lining the pocket and helix α2 are critical for PA binding and transfer. In addition, a hydrophilic patch on the surface of Ups1 near the PA phosphate-binding site also plays an important role in the function of Ups1-Mdm35. Our study reveals the molecular basis of the function of Ups1-Mdm35 and sheds new light on the mechanism of intramitochondrial phospholipid transport by the MSF1/PRELI family proteins.

An epidemiological study of etiology and clinical characteristics in patients with nontraumatic osteonecrosis of the femoral head.

BACKGROUND: Osteonecrosis of the femoral head (ONFH) is a common disease with high disability rate. However, a few studies investigate the etiology and clinical characteristics of nontraumatic ONFH patients in China. Therefore, we conducted this cross-sectional study. MATERIALS AND METHODS: Totally, information of 7268 nontraumatic ONFH patients treated between August 2005 and August 2015 was extracted from the medical records. The extracted information included the age, gender, diagnostic criteria, cause of nontraumatic ONFH, types of steroid use, and types of alcohol. RESULTS: Among these included patients, there were 5126 (70.5%) male patients with average age of 44.5 years and 2142 (29.5%) female patients with average age of 47.6 years (P = 0.54). The number of steroid-, alcohol-, steroid/alcohol-, and idiopathic-induced nontraumatic ONFH men patients was 1684, 2310, 364, and 768, respectively, and nontraumatic ONFH women patients was 1058, 482, 140, and 462, respectively. Meanwhile, we found that both the levels of triglycerides (P = 0.03) and low-density lipoprotein (P = 0.02) were significantly changed in the idiopathic-induced nontraumatic ONFH patients. CONCLUSION: These results indicated the earlier onset of nontraumatic ONFH in male patients than in female patients, different main etiology for male (alcohol consumption) and female (steroid use) patients, and close relationship between the lipid metabolism and idiopathic-induced nontraumatic ONFH. Our findings could be helpful for researchers to investigate the pathogenesis of ONFH and aid the clinicians in the early prevention and diagnosis of nontraumatic ONFH.

Crystal structures of S6K1 provide insights into the regulation mechanism of S6K1 by the hydrophobic motif.

The activity of S6K1 (p70 ribosomal protein subunit 6 kinase 1) is stimulated by phosphorylation of Thr389 in the hydrophobic motif by mTORC1 (mammalian target of rapamycin complex 1) and phosphorylation of Thr229 in the activation loop by PDK1 (phosphoinositide-dependent kinase 1); however, the order of the two events is still ambiguous. In the present paper we report six crystal structures of the S6K1 kinase domain alone or plus the hydrophobic motif in various forms, in complexes with a highly specific inhibitor. The structural data, together with the biochemical data, reveal in vivo phosphorylation of Thr389 in the absence of Thr229 phosphorylation and demonstrate the importance of two conserved residues, Gln140 and Arg121, in the establishment of a hydrogen-bonding network between the N-lobe (N-terminal lobe) and the hydrophobic motif. Phosphorylation of Thr389 or introduction of a corresponding negatively charged group leads to reinforcement of the network and stabilization of helix αC. Furthermore, comparisons of S6K1 with other AGC (protein kinase A/protein kinase G/protein kinase C) family kinases suggest that the structural and sequence differences in the hydrophobic motif and helix αC account for their divergence in PDK1 dependency. Taken together, the results of the present study indicate that phosphorylation of the hydrophobic motif in S6K1 is independent of, and probably precedes and promotes, phosphorylation of the activation loop.

Clinical effect analysis of different treatment schemes for children with ulnar and radial double fractures.

Objective: The objective of the study is to evaluate the safety and efficacy of three different treatment methods for pediatric ulnar and radial double fractures. Methods: 120 children with ulnar and radial double fractures were included in the study. According to the different treatment plans, children were divided into three groups: manual reduction, splint external fixation, double elastic intramedullary fixation, and double plate fixation. Surgical indicators, radiological results, clinical efficacy, and complications were evaluated and compared among the groups. Results: The average hospital stay and operation time were significantly longer in the double plate internal fixation group compared to the other two groups. The double elastic intramedullary nailing group showed a higher fracture healing rate at 3 months compared to the other groups. There were no significant differences in clinical efficacy among the three groups. Complications were observed in all groups but did not show significant statistical differences. Conclusion: Double elastic intramedullary nailing fixation demonstrated favorable outcomes in terms of surgical indicators and fracture healing rates for pediatric ulnar and radial double fractures.

Objetivo: Evaluar la seguridad y eficacia de tres métodos de tratamiento diferentes para las fracturas dobles cubital y radial pediátricas. Métodos: Se incluyeron en el estudio 120 niños con fracturas dobles de cúbito y radio. Según los diferentes planes de tratamiento, los niños se dividieron en tres grupos: reducción manual, fijación externa con férula, fijación intramedular doble elástica y fijación con doble placa. Se evaluaron y compararon entre los grupos indicadores quirúrgicos, resultados radiológicos, eficacia clínica y complicaciones. Resultados: La estancia hospitalaria promedio y el tiempo de operación fueron significativamente más prolongados en el grupo de fijación interna con doble placa en comparación con los otros dos grupos. El grupo de clavo intramedular elástico doble mostró una mayor tasa de curación de la fractura a los 3 meses en comparación con los otros grupos. No hubo diferencias significativas en la eficacia clínica entre los tres grupos. Se observaron complicaciones en todos los grupos pero no mostraron diferencias estadísticas significativas. Conclusión: La fijación con clavo intramedular elástico doble demostró resultados favorables en términos de indicadores quirúrgicos y tasas de curación de fracturas pediátricas dobles cubital y radial.

Self-Enhancement of Perfluorinated Sulfonic Acid Proton Exchange Membrane with Its Own Nanofibers.

High-performance proton exchange membrane (PEM) is crucial for the proton exchange membrane fuel cell (PEMFC). Herein, a novel "self-enhanced" PEM is fabricated for the first time, which is composed of perfluorinated sulfonic acid (PFSA) resin and its own nanofibers as reinforcement. With this strategy, the interfacial compatibility issue of conventional fiber-reinforced membranes is fully addressed and up to 80 wt% loading of PFSA nanofibers can be incorporated. Furthermore, on account of chain orientation within the PFSA nanofiber, single fiber exhibits super-high conductivity of 1.45 S cm-1, leading to state-of-the-art proton conductivity (1.1 S cm-1) of the as-prepared "self-enhanced" PEM so far, which is an order of magnitude increase compared with the bulk PFSA membrane (0.29 S cm-1). It surpasses any commercial PEM including the popular GORE-SELECT and Nafion HP membranes and is the only PEM with conductivity at 100 S cm-1 level. In addition, the mechanical strength and swelling ratio of membranes are both substantially improved simultaneously. Based on the high-performance "self-enhanced" PEM, high peak power densities of up to 3.6 W cm-2 and 1.7 W cm-2 are achieved in H2-O2 and H2-Air fuel cells, respectively. This strategy can be applied in any polymeric electrolyte membrane.

Design of Gradient Ti Reconstituted Fe2O3 Anodes with Enhanced Lithium Affinity Modulated Electronic Structures: First-Principles Calculations and Experiment Verification.

High-performance conversion transition metal oxides are strong candidates for advanced anode materials for lithium-ion batteries. However, the poor intrinsic conductivity and the large volume changes during battery operation are important constraints to its practical application. The heterogeneous atom doping strategy is an important way to modulate the electronic structure and surface states of the host materials. Herein, theoretical calculations reveal that heteroatomic Ti doping and its ionic or electronic compensation mechanisms can well modulate the electronic structure of Fe2O3 and change the surface Li-ion affinity. A Ti concentration gradient modification strategy for Fe2O3 is proposed to construct high-performance electrode materials. As a Li-ion battery anode, Ti concentration gradient-doped Fe2O3 achieves excellent long-cycle stability, with a reversible capacity of 1001.9 mAh g-1 at 1 A g-1 for 1200 cycles, and even maintains a reversible specific capacity compared to the theoretical capacity of commercial graphite electrodes at 2 A g-1 for 2000 cycles. This combination of theoretical calculations and experiments offers ways to intelligently design and develop alkali metal ion batteries.

Toward ultra-tough and heat-resistant biodegradable polylactide/core-shell rubber blends by regulating the distribution of rubber particles with stereocomplex crystallites.

Ultra-tough and heat-resistant poly(l-lactide)/core-shell rubber (PLLA/CSR) blends were fabricated by utilizing stereocomplex (SC) crystallites to effectively regulate the CSR distribution in PLLA matrix. Linear and 3-11 armed poly(d-lactide)s (PDLAs) were synthesized and then melt-mixed with PLLA/CSR blend. Interestingly, the incorporated PDLA chains could collaborate with PLLA chains to form dense SC crystallites network in PLLA/PDLA/CSR blends, thus inducing the CSR particles to transform from uniform distribution structure to network-like structure. With increasing the PDLA arm numbers, the size of CSR clusters in the network-like structure first increased and then decreased, and the continuity of the network-like structure first remained at a high level and then decreased obviously. The formation of CSR network-like structure could remarkably improve the impact strength of PLLA/PDLA/CSR blends without deteriorating their strength and modulus (compared with PLLA/CSR blend), and the CSR network-like structure with larger-sized CSR clusters and higher continuity could help obtain higher impact strength (78.3 kJ/m2). Moreover, the heat resistance of PLLA/PDLA/CSR blends could also be significantly improved (the highest Vicat softening temperature was 131 °C) by the SC crystallites network and CSR network-like structure. This work provides an effective strategy for controlling the rubber network-like morphology and thereby preparing high-performance PLLA materials.

Synergy of multiple precipitate/matrix interface structures for a heat resistant high-strength Al alloy.

High strength aluminum alloys are widely used but their strength is reduced as nano-precipitates coarsen rapidly in medium and high temperatures, which greatly limits their application. Single solute segregation layers at precipitate/matrix interfaces are not satisfactory in stabilizing precipitates. Here we obtain multiple interface structures in an Al-Cu-Mg-Ag-Si-Sc alloy including Sc segregation layers, C and L phases as well as a newly discovered χ-AgMg phase, which partially cover the θ' precipitates. By atomic resolution characterizations and ab initio calculations, such interface structures have been confirmed to synergistically retard coarsening of precipitates. Therefore, the designed alloy shows the good combination of heat resistance and strength among all series of Al alloys, with 97% yield strength retained after thermal exposure, which is as high as 400 MPa. This concept of covering precipitates with multiple interface phases and segregation layers provides an effective strategy for designing other heat resistant materials.