Supplementary materials

Supplementary material

Noncrystallographic Atomic Arrangement Driven Enhancement of the Catalytic Activity of Au Nanoparticles

Determining the atomic-scale structure of nanosized particles remains a challenge and crucial goal for today’s science and technology. We investigate the atomic-scale structure of 3–8 nm Au particles obtained by a fast solution reaction and find it to be of a noncrystallographic icosahedral type, in particular, close to the particles’ surface. This noncrystallographic structure may well explain the previously observed but poorly understood enhancement of the particles’ catalytic properties. Our finding demonstrates that together with size the structure type of nanosized particles can be used as a tunable parameter for achieving improved functionality

Structural Correlation to Piezoelectric and Ferroelectric Mechanisms in Rhombohedral Pb(Zr,Ti)O₃ Ceramics by in-Situ Synchrotron Diffraction

The evidence of fundamental lattice strain and domain switching contribution to the piezoelectric and ferroelectric responses of ceramics has been well studied, while the contribution from crystal structure variation has been rarely reported in terms of the existence of intergranular stress/strain and crystallographic texture. In the present study, the detailed electric field induced structure evolution in rhombohedral Pb­Zr_0.55­Ti_0.45O₃ (PZT55) has been investigated by in-situ high-energy synchrotron diffraction. The phase of PZT55 is stable in the rhombohedral one against bipolar electrical loading. It is interesting to find that both spontaneous polarization and unit cell volume exhibit a butterfly shape in response to electric field. Direct evidence has revealed that the lattice strain and volume expansion show similar variation tendency to the piezoelectric response in the rhombohedral PZT55. The macro-polarization of PZT55 derives from the combination of domain switching and spontaneous polarization change

Morphological and Crystalline Evolution of Nanostructured MnO₂ and Its Application in Lithium–Air Batteries

Single-crystal α-MnO2 nanotubes have been successfully synthesized by microwave-assisted hydrothermal of potassium permanganate in the presence of hydrochloric acid. The growth mechanism including the morphological and crystalline evolution has been carefully studied with time-dependent X-ray diffraction, electron microscopy, and controlled synthesis. The as-synthesized MnO2 nanostructures are incorporated in air cathodes of lithium–air batteries as electrocatalysts for the oxygen reduction and evolution reactions. The characterization reveals that the electrodes made of single-crystalline α-MnO2 nanotubes exhibit much better stability than those made of α-MnO2 nanowires and δ-MnO2 nanosheet-based microflowers in both charge and discharge processes

Giant Enhancement and Anomalous Thermal Hysteresis of Saturation Moment in Magnetic Nanoparticles Embedded in Multiwalled Carbon Nanotubes

We report high-energy synchrotron X-ray diffraction spectrum and high-temperature magnetic data for multiwalled carbon nanotubes (MWCNTs) embedded with Fe and Fe₃O₄ nanoparticles. We unambiguously show that the saturation moments of the embedded Fe and Fe₃O₄ nanoparticles are enhanced by a factor of about 3.0 compared with what would be expected if they would be unembedded. More intriguingly the enhanced moments were completely lost when the sample was heated up to 1120 K, and the lost moments were completely recovered through two more thermal cycles below 1020 K. These novel results cannot be explained by the magnetism of the Fe and Fe₃O₄ impurity phases, the magnetic proximity effect between magnetic nanoparticles and carbon, and the ballistic transport of MWCNTs

Structure Identification of Two-Dimensional Colloidal Semiconductor Nanocrystals with Atomic Flat Basal Planes

Discrete nature of thickness and flat basal planes of two-dimensional (2D) nanostructures display unique diffraction features. Their origin was uncovered by a new analysis method of powder X-ray diffraction, which reveals thickness and lattice orientation of the 2D nanostructures. Results indicate necessity of adoption of a different unit cell from the corresponding bulk crystal with the same internal atomic packing. For CdSe 2D nanostructures with zinc blende atomic packing, pseudotetragonal lattices are adequate, instead of face-centered cubic

Size, Shape, and Internal Atomic Ordering of Nanocrystals by Atomic Pair Distribution Functions: A Comparative Study of γ-Fe₂O₃ Nanosized Spheres and Tetrapods

Size, Shape, and Internal Atomic Ordering of Nanocrystals by Atomic Pair Distribution Functions: A Comparative Study of γ-Fe2O3 Nanosized Spheres and Tetrapod

Realization of Anomalous Floquet Insulators in Strongly-Coupled Nanophotonic Lattices

We experimentally realized Floquet topological photonic insulators using a square lattice of direct-coupled octagonal resonators. Unlike previously reported topological insulator systems based on microring lattices, the nontrivial topological behaviors of our system arise directly from the periodic evolution of light around each octagon to emulate a periodically-driven system. By exploiting asynchronism in the evanescent coupling between adjacent octagonal resonators, we could achieve strong and asymmetric couplings in each unit cell, which are necessary for observing Anomalous Floquet Insulator behaviors. Direct imaging of scattered light from fabricated samples confirmed the existence of chiral edge states as predicted by the topological phase map of the lattice. In addition, by exploiting the frequency dispersion of the coupling coefficients, we could also observe topological phase changes of the lattice from normal insulator to Chern and Floquet insulators. Our lattice thus provides a versatile nanophotonic system for investigating 2D Floquet topological insulators

Additional file 1 of Adaptive evolutionary strategy coupled with an optimized biosynthesis process for the efficient production of pyrroloquinoline quinone from methanol

Additional file 1: Fig. S1. HPLC chromatograms of (A) PQQ standard solution (614 mg/L), (B) culture medium after 48 h fermentation and (C) culture medium after 140 h fermentation by adding two volumes of water (diluted three times). Fig. S2. The calibration curve of peak areas of PQQ standard solution measured by HPLC vs. different PQQ concentration (877 mg/L, 789 mg/L, 702 mg/L, 614 mg/L, 526 mg/L, 439 mg/L, 351 mg/L, 263 mg/L, 175 mg/L, 87.7 mg/L, 43.9 mg/L). Fig. S3. Verification of the ARTP-ALE derived mutant strains isolated from the high-throughput screening. (A) PQQ production and OD650 values of thirty ARTP-ALE derived mutant strains with the highest values at A330 nm/OD650 for fermentation in shaker flasks; (B) Genetic stability of five ARTP-ALE derived mutant strains and the wild strain FJNU-6 after nine consecutive passages. Fig. S4. One-factor-at-a-time optimization of five factors. (A) methanol; (B) (NH4)2SO4; (C) KH2PO4; (D) Na2HPO4; (E) MgSO4; The same letter on the bars denote insignificant variations among the levels of the factors (p > 0.05). Table S1. Primers used for qRT PCR. Table S2. Matrix and results of Response Surface Methodology (RSM) experiments. Table S3. ANOVA analysis results for Box–Behnken Design (BBD) experiments

Negative temperature-dependence of stress-induced R→B19′ transformation in nanocrystalline NiTi alloy

The temperature dependence of the critical stress of R→B19’ transformation in NiTi shape memory alloys remains unclear due to the difficulties in precisely identifying the phase constitution and acquiring sole R phase. Here we investigate the thermally- and stress-induced martensitic transformation in a near-equiatomic nanocrystalline NiTi alloy. In situ synchrotron X-ray diffraction is used to identify the phase evolution such that the temperature window for sole R phase is firmly determined. We find that the temperature dependence of R→B19’ is negative (−0.2 MPa/K) in our alloy, in sharp contrast to 3–5 MPa/K reported. Possible reasons for the discrepancies are discussed. Negative temperature-dependence of stress-induced R→B19’ transformation was discovered for the first time in NiTi alloys, being in sharp contrast to previous reports. This calls for a revisit of such transformation.</p