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[Display omitted] We present a short peptide of only six amino acids that can be used in ambient conditions to simultaneously reduce either Au3+ or Ag+ ions, forming nanoparticles, and function as a stabilizing capping agent. At acidic pH, Hg2+ ions oxidize the silver nanoparticles and Fe2+ ions promote the aggregation of the gold nanoparticles. At alkaline conditions, Mn2+ ions induce the aggregation of the silver nanoparticles. Through the absorbance changes of these processes, these peptide-capped nanoparticles demonstrated a fast, selective, and sensitive pH-dependent detection system. The limit of detection of Hg2+, Mn2+, and Fe2+ was 319 nм, 184 nм, and 320 nм, respectively. Furthermore, the formed gold nanoparticles were successfully enveloped by a silver shell in a peptide-mediated photoreduction process. These bimetallic Au@Ag core/shell nanoparticles were characterized using UV–vis spectroscopy, high-resolution scanning transmission electron microscopy (HR-STEM), and energy dispersive X-ray spectroscopy (EDS). While prior studies used peptides as ligands for nanoparticles, the versatile abilities of the novel peptide presented in this study display the promising potential of using peptides for nanoparticles synthesis. This is because a single peptide can be used in a single-step one-pot synthesis to prepare and stabilize AuNPs, AgNPs, and Au@Ag core/shell nanoparticles, while also allowing to selectively probe different metal ions. [ABSTRACT FROM AUTHOR]

Up to 17 GPa, the crystalline phases of N2 are characterized by pronounced orientational disorder, whereas the higher-pressure phases of molecular N2 are ordered. This raises the question about long-term relaxation of orientational disorder within the low- to intermediate-pressure regime. Here, this question is addressed by comparing synthetic with natural, chemically pure, solid N2 that resides as inclusions in diamonds at 300 K for about 108 years at pressures up to 11 GPa. It is shown that disorder prevails at 8.7 GPa, 300 K, where both synthetic and natural N2 assume the same structure. However, at 10.8 GPa, natural solid N2 exhibits monoclinic distortion and partial orientational ordering of the molecules, both of which are not observed in synthetic material. This difference is interpreted as the result of long-term structural relaxation. The ordering mechanism is examined and placed into the context of the δ- to ε-N2 transition. We present explanations for the absence of complete ordering of δ-N2. [ABSTRACT FROM AUTHOR]

A unique on-chip method for the direct correlation of optical properties, with atomic-scale chemical–structural characteristics for a single quantum dot (QD), is developed and utilized in various examples. This is based on performing single QD optical characterization on a modified glass substrate, followed by the extraction of the relevant region of interest by focused-ion-beam–scanning electron microscope processing into a lamella for high resolution scanning transmission electron microscopy (STEM) characterization with atomic scale resolution. The direct correlation of the optical response under an electric field with STEM analysis of the same particle allows addressing several single particle phenomena: first, the direct correlation of single QD photoluminescence (PL) polarization and its response to the external field with the QD crystal lattice alignment, so far inferred indirectly; second, the identification of unique yet rare few-QD assemblies, correlated directly with their special spectroscopic optical characteristics, serving as a guide for future designed assemblies; and third, the study on the effect of metal island growth on the PL behavior of hybrid semiconductor–metal nanoparticles, with relevance for their possible functionality in photocatalysis. This work, therefore, establishes the use of the direct on-chip optical–structural correlation method for numerous scenarios and timely questions in the field of QD research. [ABSTRACT FROM AUTHOR]

Abstract: Structural defects, found in gallium-phosphide nanowires, grown from Au catalyst on InP 〈111〉B substrate using metal organic molecular beam epitaxy, were extensively studied using Transmission Electron Microscopy (TEM). Several types of growth were analyzed: pure axial, axial–lateral and self catalyzed. Pure axially grown nanowires were found to be single crystals with wurzite crystal structure and Ga-polarity. These nanowires contained threading edge dislocation along the wire axis. The axial–lateral nanowires grew with zinc blend crystal structure and exhibited polycrystalline nature. Self catalyzed single crystalline nanowires possessed wurzite crystal structure with P-polarity and exhibited threading edge dislocations along their axis. [Copyright &y& Elsevier]

Abstract: In course of a study of high strength, ductile alloys based on the Mg–Li system, we have identified a new quaternary phase with a composition of Mg31Zn26Ca13Li8. The structure of this phase was investigated by Transmission Electron Microscopy (TEM) using the Convergent Beam Electron Diffraction (CBED) technique. Full atomic model is proposed using direct methods applied to powder X-ray diffraction data. The phase has a cubic primitive unit cell with lattice parameter a = 9.386(8)Å and its crystal symmetry belongs to the (No. 200) space group. The unit cell of the new phase exhibits a new structure type, which is a variant of the Mg2Zn11 structure. The reliability factors characterizing the Rietveld refinement procedure are: R p = 8.6%, R wp = 12.4%, R B = 6.9% and R f = 4.4%. [Copyright &y& Elsevier]

Abstract: A strong and ductile Mg–6.0%Zn–1.0%Y–0.6%Ce–0.6%Zr alloy was developed. The alloy was first cast into billets which were rapidly solidified into ribbons, comminuted and extruded. Some of the extrusions were subjected to reciprocal extrusion processing. The microstructures of the alloy prepared by the different processes were analyzed by optical microscopy (OM) as well as high resolution scanning electron microscopy (HRSEM) and transmission electron microscopy (TEM). The microstructure of the cast consisted of coarse grains with average grain size of about 45μm with intermetallic networks at grain boundaries. The microstructure of the extrusions made of rapidly solidified chips was not uniform; it was fine at the circumference, but coarser in the central area. A low density of defects in the form of unwelded rapidly solidified (RS) ribbon particles in the center of the extrusion was also present. The microstructure of the alloy subjected to reciprocating extrusion was more uniform with average grain size of 1.3μm and homogeneously dispersed strengthening particles 80nm in diameter. [Copyright &y& Elsevier]

The coarsening of supported nanoparticles is an inevitable process that has a significant impact on the properties of materials. However, due to the limitation of experimental techniques, the atomistic kinetic mechanisms of coarsening remain largely unknown. In this work, we simulated the coarsening process of supported nanoparticles using the phase-field crystal (PFC) model in 2D and examined the influence of substrates' lattice structure on the kinetics of coarsening. The simulation results show that the particle size distribution (PSD) is consistent with mean field methods for the coarsening of triangular structured particles on the fcc(111) face, while the PSD is of a log-normal type for the coarsening on the fcc(110) and fcc(100) faces, which is consistent with the contact model of coarsening. The coarsening of supported nanoparticles is diffusion controlled, and the order of coarsening rate is K(111) > K(110) > K(100). Also, we investigated the influence of lattice mismatch on the coarsening process and found that the coarsening rate decreases with the lattice mismatch. In addition, we observed a superlattice on the surface of the particles using the PFC model, which is similar to previous experimental results, and analyzed the effect of the superlattice on the coarsening of the nanoparticles. [ABSTRACT FROM AUTHOR]

A detailed and systematic investigation on the effect post heat treatment has on the microstructure evolution and the resultant mechanical properties of the wire arc additive manufacturing processed Mg-5.9Gd-2.8Y-0.7Zr alloy is conducted in this work. The microstructure of the as-built sample is composed mainly of fine equiaxed α-Mg grain and Mg24(Gd, Y)5 phase. The solution heat treatment (400°C × 1 h) has relatively little effect on grain size, but it can effectively reduce the content of the Mg24(Gd, Y)5 phase, which leads to a significantly improved elongation with slightly decreased strength. Further ageing heat treatment at 200°C induces prismatic β' precipitates formation and does not influence other phases and grain size. The samples directly following the peak ageing heat treatment process demonstrate the best tensile properties with yield strength of 227 ± 9 MPa, ultimate tensile strength of 350 ± 4 MPa and elongation of 5.5 ± 0.6%. [ABSTRACT FROM AUTHOR]

Top‐down fabricated nanoantenna architectures of both metallic and dielectric materials show powerful functionalities for Raman and fluorescence enhancement with relevance to single molecule sensing while inducing directionality of chromophore emission with implications for single photon sources. We synthesize the smallest bow‐tie nanoantenna by selective tip‐to‐tip fusion of two tetrahedral colloidal quantum dots (CQDs) forming a dimer. While the tetrahedral monomers emit non‐polarized light, the bow‐tie architecture manifests nanoantenna functionality of enhanced emission polarization along the bow‐tie axis, as predicted theoretically and revealed by single‐particle spectroscopy. Theory also predicts the formation of an electric‐field hotspot at the bow‐tie epicenter. This is utilized for selective light‐induced photocatalytic metal growth at that location, unlike growth on the free tips in dark conditions, thus demonstrating bow‐tie dimer functionality as a photochemical reaction center. [ABSTRACT FROM AUTHOR]

Top‐down fabricated nanoantenna architectures of both metallic and dielectric materials show powerful functionalities for Raman and fluorescence enhancement with relevance to single molecule sensing while inducing directionality of chromophore emission with implications for single photon sources. We synthesize the smallest bow‐tie nanoantenna by selective tip‐to‐tip fusion of two tetrahedral colloidal quantum dots (CQDs) forming a dimer. While the tetrahedral monomers emit non‐polarized light, the bow‐tie architecture manifests nanoantenna functionality of enhanced emission polarization along the bow‐tie axis, as predicted theoretically and revealed by single‐particle spectroscopy. Theory also predicts the formation of an electric‐field hotspot at the bow‐tie epicenter. This is utilized for selective light‐induced photocatalytic metal growth at that location, unlike growth on the free tips in dark conditions, thus demonstrating bow‐tie dimer functionality as a photochemical reaction center. [ABSTRACT FROM AUTHOR]

Zinc chalcogenides nanostructures are promising newly‐studied materials for photocatalytic reactions such as water reduction for hydrogen generation and photoinitiation of radical polymerization processes. Herein, we introduced a straightforward synthesis of thin ZnS shell on ZnSe nanorods and characterized the resulting core/shell ZnSe/ZnS nanorods by electron microscopy techniques and X‐ray photoelectron spectroscopy. Then, the photocatalytic activities of the nanorods were studied by gas chromatography for hydrogen generation and by Fourier transform infrared spectroscopy for the photoinitiation capability. While such core/shell systems may limit charge transfer to the solution due to the type‐I band alignment, we find that the photochemical stability and photocatalytic activity of this system is significantly enhanced over pristine ZnSe nanorods. ZnSe/ZnS nanorods with Ni(NO3)2 co‐catalyst are used for hydrogen generation and the effects of the nanorods' surface coating, pH conditions and type of hole scavenger are examined. The best performances were observed for nanorods after ligand stripping with Meerwein′s reagent using ascorbic acid as a hole acceptor at pH 4.5. All three parameters were found to affect the photocatalytic activity. Yet, the surface coating and pH dependence differ from previous reports on cadmium chalcogenides photocatalysts. The origin of their differences is discussed and attributed to the band alignment of the systems and the nature of the co‐catalyst. The stable heavy‐metal free ZnSe/ZnS nanorods system presented here holds promise for various photocatalytic applications. [ABSTRACT FROM AUTHOR]

The thin-wall Mg-3.82Y-2.46Nd-0.56Zr (WE43) alloy component was fabricated using cold metal transfer-based wire arc additive manufacturing technology (WAAM-CMT) and the way in which microstructure evolution influences the corresponding mechanical properties in different height zones was studied. The thin-wall WE43 alloy component was mostly composed of fully equiaxed grains that had low texture strength. As a result of the layer-by-layer deposition, its microstructure exhibited obvious layer characteristics, mainly including melt pools (MP) with coarse equiaxed grains and melt pool boundaries (MPBs) with fine equiaxed grains. The grain size of the thin wall in the building direction decreased from 25.3 ± 1.2 µm in the bottom zones to 22.3 ± 0.7 µm in the top zones, whereas the content of the second phase increased. No obvious anisotropy was observed in the mechanical properties of the thin wall. The top zone specimens were found to have the best mechanical properties with ultimate tensile strength (UTS) of 233 MPa, yield strength (YS) of 153 MPa and elongation (EL) of 10.4%. In comparison to the bottom zone specimens, improvement in the mechanical properties of the top zone specimens resulted from secondary phase strengthening and grain boundary strengthening. ● The fully equiaxed grain microstructure and low base texture strength of Mg-Y-Nd alloys fabricated by WAAM. ● No obvious anisotropy in the tensile properties of the thin wall was observed. ● The cold material transfer technology and oscillation treatment resulted in low heat input and melt pool disturbance. [ABSTRACT FROM AUTHOR]