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The molybdenum dioxide (MoO2)–molybdenum carbide (Mo2C) heterostructures were built by in situ forming the (100) plane of Mo2C nanoparticles along the (101) plane of MoO2 nanoparticles and were simultaneously anchored on a 3D holey carbon substrate via optimized annealing of the bio-inspired ammonium molybdate tetrahydrate-agar gel. Both experimental results and theoretical simulations demonstrated the important roles of wide interfaces between MoO2 and Mo2C in improving the electrochemical performance of MoO2-based electrodes. These uniquely prepared MoO2/Mo2C/C electrodes delivered a capacity of 845.2 mA h g−1 at 0.1 A g−1 after 200 cycles, with a capacity change rate of 2.3%, overcoming the key obstacle for commercial application of transition metal oxides caused by capacity changes during the cycling process. Meanwhile, the electrodes displayed ultrastable long cycling performance with a capacity of 507.3 mA h g−1 at a high current density of 1.0 A g−1 after 2400 cycles, still far higher than the theoretical capacity of carbon materials. Both a local in-built driving force in the electrodes and synergistically induced more efficient mass transport across the interface were predicted by the Density Functional Theory (DFT) and Density of States (DOS) calculations from the formed interfacial electric field, yielding the fast reaction kinetics and outstanding lithium storage ability. This work highlights an efficient strategy to obtain ultrastable long cycling performance and also excellent electrochemical performance of MoO2-based materials and other transition metal oxides as anodes for lithium ion batteries. In addition, the full batteries based on MoO2/Mo2C/C anodes and a commercial LiCoO2 cathode present stable cycling performance.

Using first-principles calculations based on density functional theory, we systematically study the adsorption and diffusion behaviors of single oxygen (O) atom on the (0 0 1) surfaces of TiN, ZrN and HfN nitride coatings. The top of N site (top(N)) is the most energetic favorable site for O atom and followed by the hollow site for all the three nitrides. O atom tends to diffuse on the (0 0 1) surfaces of the nitrides from the top of transition metal top(TM) sites to a neighboring top(TM) sites by avoiding N sites. The adsorption of O on ZrN and HfN is more stable than that on TiN. Our findings could explain the experimental phenomenon that the oxide thickness of TiN is smaller than that of ZrN under the same oxidation conditions.

Based on 18 bulk diffusion couples, the composition-dependent interdiffusion coefficients in the fcc Co-V-Mo alloys at 1273, 1373 and 1473 K were obtained from the intersection points of the diffusion couples by means of EPMA technique coupled with the Whittle and Green method. With the experimentally determined interdiffusion coefficients and the critically reviewed experimental diffusivities available in the literature, the atomic mobilities of fcc Co-V-Mo alloys were assessed by means of Diffusion Controlled Transformation (DICTRA) software. The quality of the assessed atomic mobilities was confirmed by the comprehensive comparisons between various DICTRA-calculated diffusion behaviors and the experimental ones, including concentration profiles and diffusion paths.

High ion conductivity of anion-exchange membrane is essential for the operation of alkaline anion-exchange membrane fuel cell. In this work, we demonstrated an effective strategy to enhance the conductivity of anion-exchange membrane (AEM), by incorporation of quaternized cellulose nanocrystal (QCNC) for the first time. Morphology observation demonstrated a uniform distribution of QCNC within QPPO matrix, as well as a clear QCNC network, which led to significant enhancement in hydroxide conductivities of composite membranes, for example, 2 wt % QCNC/QPPO membrane possessed a conductivity of 160% (60 mS cm–1, @80 °C) of that of QPPO. Furthermore, H2/O2 cell performance of membrane electrode assembly based on 2 wt % QCNC/QPPO AEM showed an excellent peak power density of 392 mV cm–2 at 60 °C without back pressure, whereas that of neat QPPO AEM was only 270 mV cm–2.

The Pt-based alloys with Pt-skin or Pt-rich surface own significant structural advantages for a range of electrocatalytic reactions. Herein, we give a minireview for such catalysts, which covers a brief background introduction, the mechanisms for the activity enhancements derived from the special Pt-skin structures, the very recent advances on the preparation routes and applications of the catalysts in various electrochemical reactions, and a future perspective. Indeed the Pt-skin structured catalysts have shown great promising which in the future, may provide more opportunities for enhancing electrocatalytic performance at the molecular level.

Revealing the exact roles of nitrogen configurations and precise control of the nitrogen configuration in nitrogen-doped graphene (NG) are extremely important for realizing its advanced functions in clean energy technologies. Herein, for the first time, we established that the hydrogen evolution reaction (HER) activities of NG display definite trends due to its nitrogen configurations, which were selectively generated by using layer-structured montmorillonite (MMT) with different layer distances and functions modulated by Co2+, Ni2+, Na+, and H+ ions. We found that among the three types of N, i.e., pyridine, pyrrolic, and quaternary N, quaternary N is the most active one for HER in a metal-free NG catalyst, whereas with an introduction of trace atomic cobalt, the planar (pyridine and pyrrolic) N becomes the better one. In contrast, when trace atomic Ni is involved to replace the Co, the former results in heavily depressed HER activities for the NG catalyst. Density functional theory calculations further r...

International audience; Structural feature of equiaxed Guinier-Preston zones with the diameter of ∼2 nm in an Al-Mg-Si-Cu alloy has been systematically investigated by three-dimensional atom probe analyses, high-resolution electron microscopy and first-principles calculations. The results suggest that Si and Mg planes alternate along [001]Al with Cu atoms diversely substituting for some Si sites. An fcc-based Mg1(Si,Cu)1 model was then proposed for the first time, with expanded a, b and compressed c lattice parameters compared to Al. Meanwhile the structural evolution of Mg1(Si,Cu)1 → (Mg,Cu)1(Si,Cu)1 → β″-(Mg,Cu)1Mg4(Al,Cu)2Si4 is suggested.

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 Mn(2+). Headpiece opening was substantially stabilized by substitution of Mg(2+) with Mn(2+) 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 β-subunit leg of LFA-1. Mutations in the integrin βI domain α1/α1′ helix stabilizing either the open or the closed βI-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 β-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.

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.

The transition-metal compounds (MX) have gained wide attention as hydrogen evolution reaction (HER) electrocatalysts; however, the interaction between the non-metallic atom (X) and the metal atom (M) in MX, and the role of X in the enhanced catalytic activity of MX, are still ambiguous. In this work, we constructed a simple model [X/Ni(100)] to decipher the contribution of X towards enhancing the catalytic activity of NiX, which allows us to accurately predict the trend in HER catalytic activity of NiX based on the easily accessible physico-chemical characteristics of X. Theoretical calculations showed that the electronegativity (χX) and the principle quantum number (nX) of X are two important descriptors for evaluating and predicting the HER catalytic activity of NiX catalysts effectively. X atoms in the VIA group can enhance the HER activity of X/Ni(100) more significantly than those in the second period due to the large χX or nX. At a relatively low X coverage, the S/Ni(100) possesses the best HER activity among all of the discussed X/Ni(100) models, and the optimum surface S : Ni atomic ratio is about 22–33%. Further experiments demonstrated that the Ni–Ni3S2 catalyst with a surface S : Ni atomic ratio of 28.9% exhibits the best catalytic activity and lowest charge transfer resistance. The trend in catalytic activity of NiX with differing X offers a new possible strategy to exploit MX materials and design new active catalysts rationally.

In the literature, there are no thermodynamic assessments of the As-Si and As-Sn binary systems, and the existing thermodynamic description for the As-Ge system is not reliable. Based on the critical evaluation of literature data including both phase equilibria and thermodynamic data, thermodynamic optimizations for the three binary systems were carried out by means of CALPHAD (CALculation of PHAse Diagrams) approach. The substitution solution model was used to describe the Gibbs energies of the solutions phases including liquid, (As), (βSn), (Ge) and (Si). All of the intermetallic compounds, i.e., AsSn, As3Sn4, AsGe, As2Ge, AsSi and As2Si, were modeled as stoichiometric compounds. In the present work, the enthalpies of formation for the intermetallic compounds in the As-Sn system were re-calculated through the first-principles method in view of the inconsistency for the enthalpies of formation reported in the literature. A set of self-consistent thermodynamic parameters for each binary system was obtained by means of Thermo-Calc software. A regularity for the melting points, enthalpies of melting and enthalpies of formation of the AsSi, AsGe, and AsSn is observed. The calculated results were in good agreement with the experimental data.

Solid ammonia borane is a promising hydrogen storage material but suffers from a slow and ill-controlled dehydrogenation process. We studied intrinsic point defects that might play a role for hydrogen release by means of first-principles calculations augmented with van der Waals (vdW) corrections. The vdW corrections proved to be crucial for structural properties and also for energies in some cases. For vacancy and interstitial defects of single H as well as of molecular (NH3, BH3) type, we determined formation energies and local lattice structures of the defects in various charge states. Atomic H-related vacancies and interstitials exist predominantly in charged states in agreement with their chemical, i.e., protonic or hydridic, character. For molecular defects, some NH3- and BH3-related neutral defects have rather low formation energies, suggesting that the dehydrogenation of undoped ammonia borane is initiated by the cleavage of the B–N bond. The relaxation pictures associated with H-related defects c...

Sb and Sb-containing compounds have been attracting a great interest as promising alternative materials for commercial anodes and liquid batteries. The Li-Sb system was studies experimentally by investigating 6 alloys with X-ray diffraction measurement, scanning electron microscopy and electron probe microanalyses. Two binary phases Li2Sb and Li3Sb were confirmed to be stable in this system. Two invariant reactions L→(Sb)+Li2Sb and L+Li3Sb→Li2Sb were identified experimentally based on the microstructures of the as-cast alloys. The eutectic point was determined to be about 40 at% Li. The enthalpies of formation for Li2Sb, αLi3Sb and βLi3Sb at 0 K were calculated by means of density functional theory and the transition enthalpy between αLi3Sb and βLi3Sb was obtained. Then, the presently obtained results, combined with a critical review of literature data, were used to develop the thermodynamic description of the Li-Sb system by means of CALPHAD method. The liquid phase was treated as (Li, Li3Sb, Sb) using an associate model. The calculated phase diagram and thermodynamic properties can reproduce the available experimental data reasonably.

Significance Complement is deposited on foreign antigens and particles and marks them for recognition by immune cells and removal by phagocytes. Immune cells have two homologous integrins, α X β 2 and α M β 2 , that recognize the complement fragment iC3b. Although it might have been suspected that these integrins would bind to the same site on iC3b, direct comparisons here show they do not. Using negative stain electron microscopy and purified integrin fragments and iC3b, we show that α X β 2 binds to two distinct sites on iC3b. A single α M β 2 integrin binds to two different sites on iC3b, each of which is distinct from those to which α X β 2 binds. Our findings reveal remarkable diversity among integrins that recognize complement and suggest possible cooperative responses.

CoNiP nanosheet array catalysts were successfully prepared on three-dimensional (3D) graphene foam using hydrothermal synthesis. These catalysts were prepared using 3D Ni-graphene foam (Ni/GF), comprising nickel foam as the 'skeleton' and reduced graphene oxide as the 'skin'. This unique continuous modified 'skeleton/skin' structure ensure that the catalysts had a large surface area, excellent conductivity, and sufficient surface functional groups, which promoted

CoNiP nanosheet array catalysts were successfully prepared on three-dimensional (3D) graphene foam using hydrothermal synthesis. These catalysts were prepared using 3D Ni–graphene foam (Ni/GF), comprising nickel foam as the ‘skeleton’ and reduced graphene oxide as the ‘skin’. This unique continuous modified ‘skeleton/skin’ structure ensure that the catalysts had a large surface area, excellent conductivity, and sufficient surface functional groups, which promoted in situ CoNiP growth, while also optimizing the hydrolysis of sodium borohydride. The nanosheet arrays were fully characterized and showed excellent catalytic performance, as supported by density functional theory calculations. The hydrogen generation rate and activation energy are 6681.34 mL min$_{−1}$ g$_{−1}$ and 31.2 kJ mol$_{−1}$, respectively, outperforming most reported cobalt-based catalysts and other precious metal catalysts. Furthermore, the stability of mockstrawberry-like CoNiP catalyst was investigated, with 74.9% of the initial hydrogen generation rate remaining after 15 cycles. The catalytic properties, durability, and stability of the catalyst were better than those of other catalysts reported previously.

A high-performance anion exchange membrane (AEM) is critical for the development of alkaline fuel cell. In this work, AEMs with an interpenetrating polymer network (IPN) are synthesized. An electron microscope clearly reveals a highly efficient “ion channel” network, which is constructed with a small amount of cation exchange groups. This specially designed ion channel leads to extraordinary hydroxide conductivity (e.g., 257.8 mS cm -1 at 80 °C) of IPN AEMs at moderate ion exchange capacity ( IEC = 1.75 mmol g − 1 ), as well as excellent long-term alkaline stability at harsh condition which showed that 81% of original conductivity can be retained after a long time for 1248 hours. Moreover, a remarkable peak power density of 1.20 W cm -2 (0.1 MPa backpressure) with nonprecious metal (FeNx-CNTs) as oxygen reduction reaction (ORR) catalyst in a fuel cell test was achieved. This work offers a general strategy to prepare high-performance AEMs based on IPN structure design.

Zhongzhe Lv,1 Jinming Ma,2 Jianchuan Wang,1 Jianmin Lu1 1Department of Orthopedics, Affiliated Zhongshan Hospital of Dalian University, Liaoning 116001, People’s Republic of China; 2School of Graduate Studies, Zunyi Medical University, Guizhou 563000, People’s Republic of ChinaCorrespondence: Jianmin LuDepartment of Orthopedics, Affiliated Zhongshan Hospital of Dalian University, No. 6 Jiefang Road, Zhongshan District, Liaoning 116001, People’s Republic of ChinaTel +86 181 467 5683Email jianmin_lu@126.comPurpose: MicroRNA-761 (miR-761) has been reported to be deregulated in many types of human cancers and play important roles in cancer genesis and progression. However, the biological roles of miR-761 in osteosarcoma (OS) and the underlying mechanisms remain largely unknown.Methods: The expression of miR-761 in OS tissues and cell lines was analyzed using RT-qPCR. A series of gain-of-function tests were performed, and status of malignancy was evaluated on basis of proliferation, migration, invasion, and apoptosis using different assays to determine the regulatory roles of miR-761 in OS cells in vivo and in vitro. Notably, the mechanisms underlying the action of miR-761 in the pathogenesis of OS were investigated using bioinformatic analysis, luciferase reporter assay, RT-qPCR and Western blotting.Results: The results showed that miR-761 expression was decreased in OS tissues and cell lines and is closely correlated with clinical stage and distant metastasis in OS patients. Patients with OS having low miR-761 expression showed worse prognosis compared to OS patients with high miR-761 expression. Restoring the miR-761 expression level decreased OS cell proliferation, migration, and invasion in vitro; promoted cell apoptosis in vitro; and impaired tumor growth in vivo. In addition, fibroblast growth factor receptor 1 (FGFR1) was found as a direct target gene of miR-761 in OS cells. Furthermore, silencing FGFR1 expression stimulated the tumor-suppressing roles of miR-761 upregulation in OS cells, whereas the activity of miR-761 overexpression in OS cells was abolished by the restoration of FGFR1 expression. Moreover, restoration of miR-761 expression deactivated the PI3K/Akt pathway in vitro and in vivo.Conclusion: These results suggest that miR-761 plays anti-cancer roles in OS by directly targeting FGFR1 and deactivating the PI3K/Akt pathway. The newly identified miR-761/FGFR1/PI3K/Akt pathway partially illustrates the mechanism of OS pathogenesis and presents a novel candidate therapeutic target for antitumor therapy.Keywords: microRNA-761, osteosarcoma, fibroblast growth factor receptor 1, PI3K/Akt pathway, pathogenesis

Background To investigate the relation between interleukin-10 (IL-10) gene rs1800871 (A/G) polymorphism and spinal tuberculosis. Material/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 (p0.05). In spinal tuberculosis group, the frequency of G allele was higher than that of A allele (p

Lithium-rich layered Li2MnO3is regarded as a new generation cathode material for lithium-ion batteries because of its high energy density. Due to the different preparation methods and technological parameters, there are a lot of intrinsic defects in Li2MnO3. One frequently observed defect in experiments is Mn antisite defect (MnLi). In this work, we study the energetics and electronic properties involving MnLiin Li2MnO3through first-principles calculations. We find that MnLican reduce the formation energy of Li vacancies around it, but increase that of O vacancies, indicating that MnLicould suppress the release of O around it and facilitate capacity retention. Both O and Mn near the MnLican participate in charge compensation in the delithiation process. Furthermore, the effect of MnLion the migration of Li and Mn is investigated. All possible migration paths are considered and it is found that MnLimakes the diffusion energy barrier of Li increased, but the diffusion energy barriers of Mn from transition metal layer to Li layer are decreased, especially for the migration of the defect Mn. The insight into the defect properties of MnLimakes further contribution to understand the relationship between intrinsic defects and electrochemical properties of Li2MnO3.

We reported an interface-induced synthesis of iron nitrogen (FeNx) enriched carbon nanotubes (FeNx-CNTs) with high activity in alkaline and acidic environment for oxygen reduction reaction (ORR) by coating polypyrrole (PPy) thin layers on iron-doped zeolitic imidazolate framework-8 (Fe-ZIF). The constructed polymer/metal-organic framework (MOF) interface suppresses the agglomeration of iron (Fe) atomic sites during the thermal activation, and thus facilitates carbon nanotubes (CNTs) formations with FeNx coordination in carbon matrix. The produced FeNx-CNTs catalyst shows excellent ORR activities with extremely high peak power density of 1.15 and 1.16 W cm−2 in anion and proton exchange membrane fuel cells, respectively.

Quaternary ammonium (QA)-type polysulfone (PSf) anion exchange membranes (AEMs) with pendant carbonyl groups were synthesized by an environmentally friendly method. Low toxicity 3-chloro-2,2-dimethylpropionyl chloride (CDPC) was chosen as an electrophilic reagent to introduce chloroalkyl groups to PSf, instead of highly toxic chloromethyl methyl ether. The experimental conditions were carefully optimized to avoid the Friedel–Crafts alkylation side reaction on the chloroalkyl group. After quaternizing with trimethylamine (TMA), AEMs were prepared by solution casting. The obtained AEMs showed good ionic conductivity and mechanical stability. The alkaline stability of these AEMs was excellent; the AEMs can maintain 95% of their initial conductivity after immersion in a 1 M NaOH aqueous solution at 80 °C for 10 days. The reason for this outstanding alkaline stability was evaluated by NMR and density functional theory calculations. The most severe degradation pathway, the SN2 reaction, can be weakened by the competing reaction between OH− and carbonyl groups. The formed intermediate oxygen anion can decrease the possibility of SN2 by reducing the electro-static potential of the QA groups. Because of the reversibility of the reaction between OH− and carbonyl groups, QA groups can survive longer in strong alkaline conditions at high temperature. Also, the possibility of SN2 reaction on the aromatic polymer chain can be decreased because of the positive charge carrier, QA groups, which are not directly attached to benzyl groups. Hoffmann elimination can not happen because there was no hydrogen atom on the β-position of QA group. These structural advantages of the synthesized AEMs suggest another strategy that the potential for generalisation to other AEM systems and to improve the alkaline stability of QA-type AEMs.

The Pb-Sr system has been critically reviewed and modeled by means of the CALPHAD (CALculation of PHAse Diagrams) approach. It contains seven stoichiometric compounds, i.e. SrPb3, Sr3Pb5, Sr2Pb3, SrPb, Sr5Pb4, Sr5Pb3 and Sr2Pb, in which the SrPb3 and Sr2Pb phases melt congruently, and the other five phases form via peritectic reactions. The enthalpies of formation for the intermetallic compounds at 0 K are provided by first-principles calculations. The liquid, fcc and bcc phases are modeled as substitutional solution phases. Both Redlich-Kister and exponential polynomials are used to describe the excess Gibbs energy of the liquid. Two sets of self-consistent thermodynamic parameters are obtained by considering reliable experimental data and the computed enthalpies of formation. Comprehensive comparisons between the calculated and measured phase diagram and thermodynamic data show that the experimental information is satisfactorily accounted for by the present thermodynamic description.

Alloying is an effective method to improve mechanical properties of some compounds. The present work predicted an alloying strategy for improving fracture toughness of C15 NbCr2 Laves phase. The lattice parameters of C15 NbCr2-based ternary compounds with transition metal elements were calculated using first principles, revealing a relationship between lattice parameters and radii of transition metal elements. The atomic free volumes of a series of C15 NbCr2-based ternary compounds with transition elements were calculated and proposed as an indicator for a knowledge-based strategy for toughening enhancement of the C15 NbCr2 Laves phase. According to the presently calculated results, Re has the largest potential to improve fracture toughness of C15 NbCr2 Laves phase, since it has the largest atomic free volume, followed by Os, Ir, Tc, Ru, Rh, Cu, Pt and Mo.

Sn and Sn-based compounds have been attracting a great interest as promising alternative materials for commercial anodes in lithium ion batteries. In this study, the phase evolution of the Li-Sn system during the lithiated processes and the effect of the elastic-strain energies caused by volume change on the phase transition are investigated by means of first-principles calculations. Our calculated results demonstrate that the distorted Li 7 Sn 3 crystal tends to be formed in order to decrease the elastic-strain energy. In addition, our work indicates that the whole lithiated processes under the elastically constrained condition could be classified into two steps. The first step is the two-phase equilibrium process, in which the thermodynamic driving force is large enough to facilitate the phase transition and the plateau voltage could be established. The second step is considered to be the selective equilibrium, in which the thermodynamic driving force is not enough to facilitate the nucleation of the new equilibrium phase due to the elastically constrained conditions and the plateau voltage unformed. Besides, we find that in the Li 0.4 Sn matrix the nucleation of the αSn is more preferential than the βSn due to the effects of the elastic-strain energies.

Pugh’s criterion in terms of the bulk/shear modulus ratio ( B / G ) is widely used to distinguish the ductility and brittleness of metals, with the recommended B / G ratio of 1.75 for the boundary ratio between ductility and brittleness. The present first-principles calculations yield a B / G = 3.69 for the C15 Laves phase NbCr 2 , suggesting the ductility of NbCr 2 according to Pugh’s criterion. However, experiments indicate that NbCr 2 is a brittle phase at room temperature with the fracture toughness of 1.0–1.4 MPa m 1/2 . NbCr 2 is hence a compound with its ductile and brittle behavior beyond Pugh’s criterion, and this finding also validates for other Laves phases and compounds. New insight into Pugh’s B / G criterion is also discussed.

Hydrothermally carbonized chitosan has been successfully used as a carbon source for the preparation of highly porous carbons via chemical activation. The porous carbons with different nitrogen contents (0.56–6.53 wt%) have high surface area (1362–3009 m 2 g −1 ) and large pore volume (0.670–1.497 cm 3 g −1 ). These properties can be varied from modifying the activation parameters ( i.e. , amount of activation agent and activation temperature). We observed hydrogen storage capacity of up to 2.71 wt% at 77 K and 1 bar, and 6.77 wt% at 20 bar, for PC-2-800 porous carbons. This result indicates that the hydrogen uptake of porous carbons mainly depends on the high micropore surface area related to optimum pore size. Furthermore, one found that high N-doping is beneficial for hydrogen storage at low pressure but it is detrimental at high pressure according to the analysis of hydrogen uptake isotherms.

A new relationship among self- and impurity diffusion coefficients has been proposed for binary solution phases and verified via 30 solid solutions. In terms of this model, one impurity diffusion coefficient in a binary phase can be predicted once the other three diffusion coefficients are available. The application of the present model is exemplified in the Al-Mg system.

Interpenetrating polymer network anion exchange membrane (IPN AEM) consists of cross-linked quaternized poly (vinylbenzyl chloride) and cross-linked poly (vinyl alcohol) is synthesized in this work. Electron microscope clearly reveals the IPN structure, and with this structural design, a highly efficient ion channel within IPN AEMs is constructed. This specially designed structure leads to high hydroxide (OH−) conductivity (e.g., 141.7 mS cm−1 at 80 °C) at a moderate ion exchange capacity (IEC) of 1.61 mmol g−1, and a remarkable peak power density of 0.64 W cm−2 with non-noble metal oxygen reduction reaction (ORR) catalyst in H2/Air (CO2-free) anion exchange membrane fuel cells (AEMFCs) test.

The pomelo peel flour (PPF) film-forming dispersions were physically modified by high-pressure homogenization (HPH) process at various pressures (0–80 MPa) to prepare biopolymer films. The effects of different HPH pressures on microstructure and properties of PPF dispersions and their resultant films were investigated. The results showed that as the homogenization pressure increased, the mean particle sizes of PPF dispersions decreased significantly from 78.76 μm to 19.87 μm, highlighting the disrupting effect of HPH. Meanwhile, the PPF dispersions after HPH exhibited a shear-thinning behavior with higher apparent viscosities and better colloidal stability, indicating the improved uniformity and consistency. Consequently, the resultant PPF films had not only more compact microstructure and transparent appearance, but also better water vapor barrier and mechanical properties. In particular, the PPF film from HPH treated dispersion at 60 MPa had relatively best performance among them, the tensile strength and elongation at break of which respectively increased from 9.88 to 23.55 MPa and 6.09% to 17.68%, while the water vapor permeability decreased from 4.10 × 10−10 to 2.08 × 10−10 g/m·s·Pa, compared to the untreated film. However, a slight deterioration in these above mentioned properties was observed for 80 MPa HPH treated films, which might be attributed to the undesirable degradations of biopolymers (such as pectin and dietary fiber) occurred at excessively high homogenization pressure. These findings reveal that HPH process has a potential application in developing novel biopolymer films from pomelo peel with enhanced properties.

Ternary Co–Ni–B amorphous alloy was synthesized by a chemical reduction method. Used as a negative electrode in the alkaline rechargeable batteries, the as-prepared alloy exhibits an excellent electrochemical performance in the temperature range of −30 to 50 °C. Specifically, the discharge capacity after 100 cycles still keeps up at 395.2, 403.7, and 379.1 mAh/g at −15, 0 and 25 °C, respectively. Even at a much lower temperature of −30 °C, the maximum discharge capacity remains to be 408.3 mAh/g and slowly decays to 317.1 mAh/g after 100 cycles. Moreover, the high-rate dischargeability at 900 mA/g is 29.6% at −30 °C. When the temperature increases to 50 °C, the discharge capacity of the Co–Ni–B alloy electrode decreases from 675.6 to 283.1 mAh/g after 100 cycles. These properties are very superior to those of conventional hydrogen storage alloy electrodes at the corresponding temperatures. The cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and anodic polarization (AP) tests show that the temperature has a crucial effect on the electrochemical kinetics of the Co–Ni–B alloy electrode.

First-principles calculations are used to investigate the site preference and diffusion of hydrogen in the initial stage of hydrogenation of Mg. The fcc-hollow site and the tetrahedral site are found to be the energetically favorable sites for hydrogen atom on and below Mg(0001) surface, respectively. When a hydrogen atom diffuses into the bulk Mg, it has to firstly overcome an energy barrier of 0.45 eV. There exist two different diffusion pathways with this energy barrier, which start from two possible surface adsorption sites. While a lower barrier of 0.31 eV is necessary for hydrogen further diffusion into the bulk region. The effect of the subsurface vacancy on hydrogenation is also investigated in terms of hydrogen trapping and diffusion barrier. At most six hydrogen atoms can be trapped by a single Mg vacancy in the subsurface. It is required at least 0.40 eV for the trapped hydrogen to escape from the vacancy. This trapping property and relatively large diffusion barrier to escape from the vacancy would prevent further diffusion of hydrogen into Mg during the initial stage of hydrogenation. The vacancy, however, has little influence on the diffusion property of its neighboring hydrogen atom.

Understanding nonlinear dielectric behavior in polar polymers is crucial to their potential application as next generation high energy density and low loss dielectrics. In this work, we studied nonlinear dielectric properties of a biaxially oriented poly(vinylidene fluoride) (BOPVDF) film under both low and high electric fields. For fundamental nonlinear dielectric constants at low fields (30 MV/m), Novocontrol high-voltage broadband dielectric spectroscopy (HVBDS) was accurate enough to measure up to the third harmonics. It was observed that the low-field dielectric nonlinearity for the BOPVDF disappeared above 10 Hz at room temperature, suggesting that the low-field dielectric nonlinearity originated from ionic migration of impurity ions rather than dipolar relaxation of the amorphous segments. Above the coercive field (EC ≈ 70 MV/m), bipolar electric displacement-electric field (D-E) loop tests were used to extract the nonlinear behavior for pure PVDF crystals, which had a clear origin of ferroelectric switching of polar crystalline dipoles and domains and nonpolar-to-polar (α → δ → β) phase transformations. By using HVBDS, it was observed that the ferroelectric switching of polar crystalline dipoles and domains in BOPVDF above the EC always took place between 20 and 500 Hz regardless of a broad range of temperature from -30 to 100 °C. This behavior was drastically different from that of the amorphous PVDF dipoles, which had a strong dependence on frequency over orders of magnitude.

A novel kind of graphene oxide-modified poly(melamine-formaldehyde) (PMF) microcapsule containing phase change material (microPCM) n-dodecanol was prepared by in situ polymerization. Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to study the chemical structure of graphene oxide (GO) and microPCMs, respectively. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to investigate the morphology of GO and microPCMs, respectively. The thermal properties of microPCMs were studied by differential scanning calorimetry (DSC), thermal constant analysis (TCA) and thermal cycling tests. The FTIR and XRD results indicate that the phase change material n-dodecanol is encapsulated in the GO/PMF composite shell, and there is no chemical reaction between them. The SEM results show that the prepared GO-modified PMF microPCMs are spherical particles with a smooth surface. The DSC results indicate that the phase change temperature and the latent heat of microPCMs with 1 wt% of GO are 26.40 °C and 125.2 J g−1, respectively. The thermal conductivity of GO/microPCMs with 4 wt% GO increases by 66.29%, compared with that of microPCMs without GO according to the TCA results. Moreover, the thermal cycling tests show that the prepared microPCMs possess a good thermal stability. The GO-modified PMF microPCMs are sure to have great potential applications in thermal energy storage.

Integrins αVβ6 and αVβ8 are specialized for recognizing pro-TGF-β and activating its growth factor by releasing it from the latency imposed by its surrounding prodomain. The integrin αVβ8 is atypical among integrins in lacking sites in its cytoplasmic domain for binding to actin cytoskeleton adaptors. Here, we examine αVβ8 for atypical binding to pro-TGF-β1. In contrast to αVβ6, αVβ8 has a constitutive extended-closed conformation, and binding to pro-TGF-β1 does not stabilize the open conformation of its headpiece. Although Mn2+ potently activates other integrins and increases affinity of αVβ6 for pro-TGF-β1 25- to 55-fold, it increases αVβ8 affinity only 2- to 3-fold. This minimal effect correlates with the inability of Mn2+ and pro-TGF-β1 to stabilize the open conformation of the αVβ8 headpiece. Moreover, αVβ8 was inhibited by high concentrations of Mn2+ and was stimulated and inhibited at markedly different Ca2+ concentrations than αVβ6 These unusual characteristics are likely to be important in the still incompletely understood physiologic mechanisms that regulate αVβ8 binding to and activation of pro-TGF-β.

Increasing requirements on hard coatings in high-performance machining processes like high speed and dry cutting demands further developments even of the already well established TiAlN coatings. The aim of this work is to present a comparative study on oxidation behavior of Ti0·5Al0·5N coatings alloyed with X (X = V, Hf, Si) elements. Ab initio molecular dynamics results showed that a pronounced layered oxide appears due to the incorporation of these alloying elements thus affecting the thermal stability and antioxygenic properties. The additions of Hf and Si facilitate the formation of layered oxides with Ti-rich and Al-rich oxides, respectively, which improves the antioxidant performance at high temperatures. Contrarily, the Al-rich layer is absent during oxidation of V-containing coating. The Ti-oxides on the surface of TiAlVN and TiAlHfN coatings have different structures due to the discrepancy of O–Ti–O angle. The present findings clearly show that the V-addition results in more rutile-like TiO2 whereas the Hf-addition leads to more anatase-like2 with O–Ti–O angle of 156.3°. With further oxidation, the structures of coatings vary significantly with the alloying elements, which indicates that the alloying of Hf and Si retards the inward diffusion of O atoms, especially, the alloying of Si leads to an earlier formation of a dense sublayer rich in Al2O3, and thus promotes the oxidation resistance. The different diffusion barrier energies of Ti and Al in TiN bulk contribute to the formation of layered oxides on the surface of coating and the different oxidation behaviors. This study provides an atomistic insight to the initial as well as further stages of the oxidation process of quaternary TiAlXN, which together with the electronic structure analysis and diffusion of metal atoms gives a new basis for understanding of its oxidation behaviors.

The diffusivities in fcc phase of the Al–Cu–Mg system are systematically predicted via first-principles calculations coupled with CALPHAD (CALculation of PHAse Diagram) technique. All the self- and impurity diffusion coefficients of fcc phase in this ternary system, including both stable and meta-stable states, are calculated via first-principles calculations. The enthalpy of vacancy formation and migration, binding enthalpy of vacancy–solute, entropy of vibration, effective atomic jump frequency, as well as the pre-factors and activation energies for diffusion in the Arrhenius equation are obtained. The atomic mobilities of the three elements are then obtained based on the first-principles calculated diffusion coefficients. Moreover, the interdiffusion coefficients of the Al–Cu, Al–Mg and Cu–Mg binary systems are calculated by means of the DICTRA (DIffusion-Controlled TRAnsformation) package in the framework of CALPHAD approach. Comprehensive comparisons between the predicted and measured diffusivities show that most of the experimental data can be well reproduced. It is found that the combination of first-principles calculations and CALPHAD technique is an effective strategy to obtain diffusivities for multicomponent systems.

Recently, nanoconfined poly(vinylidene fluoride) (PVDF) and its random copolymers have attracted substantial attention in research. In addition to the drastic change in crystallization kinetics, major interest lies in crystal orientation and polymorphism in order to understand whether enhanced piezoelectric and ferroelectric properties can be achieved. For example, PVDF has been two-dimensionally (2D) confined in cylindrical nanopores of anodic aluminum oxide (AAO) with various pore diameters. The crystal c-axis becomes perpendicular to the cylinder axes, which favors dipole switching in the impregnated AAO membrane. However, no polar phases have been obtained from 2D confinement even down to 35 nm pores after melt recrystallization. In this work, we realized three-dimensionally (3D) confined crystallization of PVDF in 180 nm nanospheres by employing a facile emulsifier-free batch seeded emulsion polymerization to prepare PVDF@polystyrene (PS) core–shell particles. Influences of polymerization temperature...

In our work, a novel modifier, quaternary phosphorus salt, (1-hexadecyl) triphenylphosphonium bromide (HTPB), was introduced for the noncovalent functionalization of graphene for the first time. With it, an excellent dispersion of graphene in organic solvent and later in poly(vinylidene fluoride) (PVDF) matrix has been achieved, e.g., transmission electron microscopy (TEM) shows a single-layer dispersion and multi-layer structure of graphene sheets in PVDF matrix. As a result, the films exhibit outstanding electric property with a very low percolation threshold of 0.662 wt% being observed. Their dielectric property is also improved, the dielectric constant of PVDF/graphene composites at 1000 Hz with a loading lower than 0.86 wt% shows an obvious increase (more than 3 times of that of PVDF at most), while the dielectric loss remain quite low (all lower than 0.07). Even more intriguingly, the quaternary phosphorus salt also induces dominant polar β and γ crystalline forms in the prepared composite films. These PVDF/graphene films with good electric and dielectric property as well as dominant polar β and γ forms promise a wide range of potential applications in electronic devices.

Using first-principles calculations, we investigated the structural properties and formation energies of H-related intrinsic defects and F- or Cl-related impurities in MgH2. It was found that hydrogen vacancy and interstitial are favorable in charged states, whereas F and Cl impurities tend to substitute for hydrogen atom with the neutral state. We showed that F and Cl cannot lead to decrease of the removal energy for neutral and negatively charged H atom, but both of them can markedly decrease the removal energy for positively charged H atom. This result provides an explanation for the experimentally observed lowering of the onset temperature for hydrogen desorption from TiF3- and TiCl3- doped MgH2.

In this paper, reduced graphite oxide (RGO) was prepared using thiourea dioxide as reductant and polyvinylpyrrolidone (PVP) as stabilizer. Thiourea dioxide, a cheap and nontoxic industrialized material, was demonstrated to be an efficient reducing agent for graphite oxide (GO) in this paper. Ultraviolet and visible (UV–vis) spectroscopy results revealed that the reduction of GO could be readily achieved in 10 min, a reaction time which is much shorter than those required in common reduction reactions. The procedures of reduction including the by-products are all nontoxic, thus it is absolutely environmentally friendly. To the best of our knowledge, this is the first time that thiourea dioxide was successfully used to prepare RGO. Moreover, the stabilizer, PVP, which could be easily absorbed onto the surface of RGO, provided RGO with good water and organic solvents solubility, with low conductivity though. However, by controlling the content of PVP, RGO with balanced solubility and conductivity can be obtained. The resultant RGO could be used as nanofillers to prepare conductive materials and biomaterials with potential applications as electrical devices or biosensors.

Polar β and γ crystalline forms, especially the β form, are of great importance to the piezoelectric/ferroelectric property of poly(vinylidene fluoride) (PVDF). Dominant polar crystal forms (containing both β and γ forms) are induced in PVDF by simply adding a small amount of dioctadecyl dimethyl ammonium chloride (DDAC, a kind of alkyl ammonium salt used to treat clay). By comparing with the PVDF/clay and PVDF/DDAC modified-clay systems, it is demonstrated that it is DDAC that induces polar β and γ forms of PVDF rather than organoclay itself. The widely accepted mechanism that crystal lattice matching between PVDF and clay induces β form in PVDF/organoclay composite might be wrong. It is also interesting to find that super tensile toughness can be achieved by adding a small amount of DDAC. These new findings are very important for the understanding of the formation mechanism of polar forms of PVDF and its application.

Microcosmic investigations of weak red-emitting materials are crucial for their further development and application. In this work, we have focused on the band structures and electronic properties of Pr mono- and (Zn, Pr) co-doped CaTiO3 using density functional theory. Zn substitution for Ca or Ti tends to form clusters energetically with Pr substituting for Ca in CaTiO3. In Pr mono-doped CaTiO3, the O2p→Ti3d transition in CaTiO3 host corresponds to the centered 330 nm excitation spectra. The gap states above the valence band of ∼1.30 eV and ∼2.06 eV are hybridized by Pr4f, O2p and Ti3d orbitals. They are mainly due to Pr4f orbitals in CaTiO3:Pr. The former gap level is related to red emission at 614 nm due to 1D2→3H4 transition of Pr3+ activator. The latter is related to the excitation spectra centered at 380 nm due to the low-lying Pr-to-mental intervalence charge transfer transitions (Pr3+–O2−–Ti4+⇌Pr4+–O2−–Ti3+). The band structures of (Zn, Pr) co-doped CaTiO3 keep the similar gap levels to those in Pr mono-doped CaTiO3. The incorporation of Zn brings out the two stronger localized gap states, which are hybridized by Pr4f, O2p and Ti3d orbitals, in comparison with those in Pr mono-doped CaTiO3. Therefore, when Zn impurities are added into Pr doped CaTiO3, the present calculations visualize the two enhanced levels and the distorted structures around Pr.